Table of Content

20 May 2024, Volume 33 Issue 5

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Quantitative classification and ordination analysis of spontaneous vegetation communities in herb layer along the green belt of Nanjing Ming City Wall

Qian LIU, Yan-fen DING, Shan-shan SONG, Wen-jie XU, Wei YANG

2024, 33(5):  1-15.  DOI: 10.11686/cyxb2023217

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The aims of this work were to explore the types and distribution of spontaneous vegetation communities in the herb layer along the green belt of the Nanjing Ming City Wall， and to determine the main environmental factors affecting them. The overall aim of our research was to provide a theoretical basis for building a green ecological corridor along the Nanjing Ming City Wall and to strengthen the protection of the ecosystem on this structure. Thirty sampling sites along the green belt of the Nanjing Ming City Wall were investigated in a field survey. Using the species importance value as an index， species diversity characteristics were analyzed on the basis of the alpha diversity index. The unweighted pair-group method with arithmetic means and canonical correspondence analysis were used to analyze the composition and distribution of the communities， and to explore the relationships between environmental factors and the spontaneous vegetation communities in the studied herb layer. It was found that： 1） The species diversity index and evenness index of spontaneous vegetation in the herb layer were high， and the species distribution was uniform. 2） The main flora communities along the green belt of the Nanjing Ming City Wall were： Trachycarpus fortunei-Veronica hederifolia+Carex chinensis+Youngia japonica； Stellaria media+Corydalis edulis+Orychophragmus violaceus+Veronica persica； V. hederifolia+Lamium barbatum+S. media+C. edulis； Elymus kamoji+L. barbatum+O. violaceus+C. edulis； Trachelospermum jasminoides-E. kamoji+V. hederifolia+Solidago canadensis； Semiaquilegia adoxoides+S. media+L. barbatum+Galium spurium； T. jasminoides-L. barbatum+O. violaceus+Thladiantha nudiflora； Rubus hirsutus+T. jasminoides-Cyclosorus acuminatus+E. kamoji； L. barbatum+E. kamoji+Oplismenus undulatifolius+Carex breviculmis； T. jasminoides-L. barbatum+V. hederifolia+O. violaceus； Rosa multiflora+T. jasminoides+Campsis radicans-Rubia cordifolia.3） The results of the canonical correspondence analysis showed that canopy density， litter thickness， wall height， and wall orientation were the main environmental factors affecting the distribution of spontaneous vegetation communities in the herb layer along the green belt of the Nanjing Ming City Wall.

Economic cost assessment of global invasive plants

Guang-hua ZHAO, Ming-long GAO, Duo WANG, Shi-qi FAN, Jian TANG, Kuo SUN, Xuan-ye WEN

2024, 33(5):  16-24.  DOI: 10.11686/cyxb2023220

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Among invasive species， plants comprise the most diverse and numerous biological groups. Assessing the economic cost of invasive plants is an important part of risk management and is essential for the development of policies for control or eradication. In this study， based on the InvaCost database， we assessed the economic costs of global invasive plants from 1970 to 2017. The main results were as follows： 1） The conservative economic cost of invasive plants from 1970 to 2017 was 194.365 billion U.S. dollars （USD）， 4.049 billion USD per year on average， of which the direct economic loss amounted to 100.468 billion USD， accounting for 51.69% of the total. 2） Among 64 countries and regions， the United States has borne the highest economic costs， followed by Australia， and China ranks third with costs of 20.831 billion USD （equivalent to 140.707 billion RMB）. Notably， Eichhornia crassipes has been the most expensive invasive plant species globally， with the costs of its damage exceeding the combined costs of invasive plants ranking 5th to 10th. 3） Over the past five decades， the economic cost of invasive plants has shown an upward trend. Model estimates suggest that the possible cost of invasive plants in 2017 ranged from 3.438 billion to 10.452 billion USD， with the highest confidence value being 7.725 billion USD. The results of this study contribute to a deeper understanding of the severity of invasive plant threats and provide a scientific basis for more proactive invasive plant management in China.

Soil fertility in perennial vegetable fields in the latosolic red soil zone of the Pearl River Delta

Jian-feng NING, Tong LI, Rui-kun ZENG, Jian-wu YAO, Yong CHEN, Zi-wei LIANG

2024, 33(5):  25-40.  DOI: 10.11686/cyxb2023301

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Latosolic red soil is the predominant soil type in Guangdong province. In this study， we explored the current status of， and changes in， the soil fertility of vegetable fields located in the latosolic red soil zone. The ultimate aim was to provide a scientific basis for evaluating the management of cultivation and fertilization during vegetable production， with a goal to protect and improve farmland. We selected 89 perennial vegetable fields， i.e.， fields cultivated with various vegetables annually， in the cities of Guangzhou， Jiangmen， and Zhaoqing， and the district of Huiyang of Huizhou city in the Pearl River Delta in Guangdong province， and collected surface soil samples for analyses of soil physicochemical parameters. The results were compared with the National Nutrient Classification Standard of The Second Soil Census and the Nemero index. It was found that loam soil， sandy loam soil， and silty loam soil were the dominant categories of soil texture， accounting for 46.1%， 23.6%， and 19.1%， respectively， of all the soil samples from perennial vegetable fields. The soil was characterized as slightly acidic （average pH， 5.83）， the organic matter content was classified as medium （average， 23.83 g·kg^-1）， and the cation exchange capacity was classified as medium-low ［average， 8.67 cmol（+）·kg^–1］. The concentrations of soil total nitrogen （N）， total phosphorus （P）， and total potassium （K） were 1.19 g·kg^-1， 1.47 g·kg^-1， and 12.53 g·kg^-1， respectively， corresponding to medium （total N， total P） and medium-low （total K） levels. The soil was rich in available N and available P （135.24 mg·kg^-1 and 120.24 mg·kg^-1， respectively） and extremely rich in available K （222.48 mg·kg^-1）. The Nemero index was 1.69， indicative of fine status of soil fertility. Compared with the data obtained for latosolic red soil in Guangdong province in The National Second Soil Census， the soil total K concentration had decreased， whereas the soil pH， organic matter content， total N， and available N had increased by 16.6%， 23.5%， 38.4%， and 62.5%， respectively， and the soil cation exchange capacity and total P， available P， and available K contents had markedly increased by 1.29-， 6.00-， 65.80-， and 3.07-times， respectively. Soil available P had accumulated substantially in most of the sampled vegetable fields. The annual accumulation rates of soil total N and total P were 8.46 mg·kg^-1 and 32.31 mg·kg^-1， respectively， and those of soil available N， available P， and available K were 1.20 mg·kg^-1， 3.04 mg·kg^-1， and 4.30 mg·kg^-1， respectively. In general， soil fertility in vegetable fields of the Pearl River Delta in the latosolic red soil zone has improved under local tillage management over the last 40 years. The soil has shifted from acid to slightly acid， the cation exchange capacity and organic matter and total N contents have improved by one grade， the available N and available K contents have improved by two grades， and the soil total P and available P have improved by three and five grades， respectively. Thus， soil fertility in the research area has improved from inferior status （i.e. extremely insufficient to medium-low level） in 1980 to the current preferable status （medium-low level to extremely rich）. To improve the fertility of vegetable fields and maintain the sustainable utilization of soil resources in the latosolic red soil zone of the Pearl River Delta， the combined application of organic manure and chemical fertilizers is recommended during local vegetable production. It will be important to use optimum inputs of N and K fertilizers and reduce inputs of P fertilizer.

Effects of drought stress and rehydration on the growth and physiological characteristics of annual herbaceous plants from a desert-oasis ecotone

Lu-jing ZENG, Guo-hua WANG

2024, 33(5):  41-57.  DOI: 10.11686/cyxb2023302

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In desert-oasis ecotones， many annual herbaceous plant populations form permanent plant synusiae， which play important roles as windbreaks and in sand fixation， thereby protecting the stability of the oasis ecosystem. In this study， we selected Chloris virgata， Setaria viridis， Halogeton arachnoideus， Agriophyllum squarrosum， and Bassia dasyphylla as five typical annual herbaceous plants under artificial forests in a typical desert-oasis ecotone in the Hexi Corridor， and conducted pot experiments with simulated drought and rehydration treatments. We measured the changes in root and leaf growth traits （i.e.， plant height， root volume， average root diameter， total root surface area， total root length， and root dry weight） and physiological characteristics （i.e.， root activity， contents of photosynthetic pigments， malondialdehyde， osmotic adjustment substances， and antioxidant enzyme activity） of seedlings of the five plants to analyze their adaptive strategies to drought stress. The results showed that light drought stress （i.e.， soil moisture decreased by 2% compared with the control） had no significant negative effect on the growth of the five annual herbaceous plants， but promoted their growth to some extent. Plant growth was significantly inhibited under moderate （soil moisture decreased by 4%） and severe （soil moisture decreased by 6%） drought stress. The contents of malondialdehyde and osmoregulatory substances and the activity of peroxidase in the roots and leaves increased with increasing severity of drought stress； but the root activity decreased significantly. The activity of superoxide dismutase in the roots of the annual Gramineae C. virgata and S. viridis increased with increasing severity of drought stress； however， its activity in the roots of A. squarrosum and B. dasyphylla （Chenopodiaceae） initially increased and then decreased with increasing severity of drought stress. Upon rehydration treatments， the growth and physiology of all five plant species were compensated to different degrees. Roots recovered better than did leaves， and shallow-rooted plants were better able to recover than deep-rooted ones. The drought tolerance of the five annual herbs differed significantly， and they were ranked from most to least drought tolerant as follows： S. viridis>H. arachnoideus>B. dasyphylla>C. virgata>A. squarrosum.

Evaluation and screening of the salt tolerance of triticale germplasm at the germination and seedling stages

Meng WANG, Xue-li LU, Ju-ying WANG, Meng-chao ZHANG, Yi-ru SONG, Chen MENG, Li ZHANG, Zong-chang XU

2024, 33(5):  58-68.  DOI: 10.11686/cyxb2023228

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Salinized soil is an important standby cultivated land resource， but salt-tolerant crop varieties are required to use salinized land for agriculture. In this study， 14 triticale （Triticosecale wittmack） germplasm lines from America and six Chinese provinces were treated with 0.9% and 1.2% （w/v） NaCl during the germination and seedling stages， respectively. The salt tolerance of triticale germplasm lines at the germination and seedling stages was evaluated and screened by measuring the germination rate， germination energy， and germination index， as well as plant height， root length， dry/fresh weight of aboveground， dry/fresh weight of roots， proline and malonaldehyde contents， and superoxide dismutase activity. The results showed that there were was abundant variation in these indexes among the salt-treated triticale materials at the germination and seedling stages， with the coefficient of variation ranging from 6.53% to 99.65%. Compared with the agronomic indexes， the physiological indexes were more strongly affected by salt stress. The salt tolerance of triticale germplasm resources at the germination stage and seedling stage was evaluated using multivariate statistical methods such as the membership function method and principal component analysis. A correlation analysis between the membership function value ranking at the germination stage and the D-value ranking at the seedling stage showed that the salt tolerance at the seedling stage was significantly positively correlated with that at the germination stage. Overall， we identified eight salt-tolerant germplasm lines at the germination stage， and one very salt-tolerant line and eight salt-tolerant lines at the seedling stage. The two most salt-tolerant materials at the germination and seedling stages were Gannong No.4 and Jisi No.2. Thus， these two materials were identified as excellent triticale resources for cultivation in saline-alkali soils and for breeding new salt-tolerant cultivars.

Regeneration and carbohydrate distribution in sweet sorghum after cutting

Pan ZHANG, Xiao-xiao LI, Fa-neng YAN, Yuan-le HE, Zhen-qing BAI, Jia-wen WU

2024, 33(5):  69-79.  DOI: 10.11686/cyxb2023215

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Sweet sorghum （Sorghum bicolor） is a vital forage crop， and cutting effectively improves its production potential. To investigate the regeneration of sweet sorghum and the distribution of carbohydrates after cutting， sweet sorghum plants were grown hydroponically for 42 days until they reached about 100 cm height in an artificially controlled climate chamber， and were then cut to a stubble height of 8 cm. Plant height， fresh weight， number of leaves， growth rate， photosynthesis， root architecture， and structural and non-structural carbohydrate contents were determined before cutting and at 7， 21， and 35 days after cutting. It was found that plant height， number of leaves， and stems and leaves fresh weight of sweet sorghum quickly recovered after cutting， reaching their pre-cutting values by 35 days after cutting. The fresh weight of roots， total root length， root surface area， and number of root tips were significantly greater at 35 days after cutting than before cutting. The growth rate at 7 days after cutting was remarkably enhanced， but the growth rates at 21 and 35 days after cutting were lower than that before cutting. The net photosynthesis rate （A） and intercellular carbon dioxide concentration （C_i） of leaves were not significantly affected by cutting， whereas the transpiration rate （E） and stomatal conductance （G_s） were significantly increased at 21 days after cutting. The sucrose and glucose contents in stems and the sucrose contents in leaves of sweet sorghum were significantly decreased at 7 days after cutting， and then increased at 21 days after cutting. By contrast， starch contents in leaves were significantly increased at 7 days after cutting， and then decreased at 21 days after cutting. The soluble carbohydrate contents of sweet sorghum at 35 days after cutting had recovered to pre-cutting levels. The sucrose contents in roots and starch contents in stems were higher at 35 days after cutting than before cutting. Cutting did not significantly affect the hemicellulose and lignin contents in roots， stems， and leaves of sweet sorghum， but resulted in significantly decreased cellulose contents in roots， stems， and leaves at 7 and 21 days after cutting. The cellulose contents in stems and leaves recovered to pre-cutting levels by 35 days after cutting. Taken together， cutting sweet sorghum promotes starch accumulation in leaves， followed by an increase of sucrose accumulation in leaves and roots， and simultaneously decreases cellulose contents. Through these dynamic regulatory mechanism， cutting stimulates growth rate to ensure regeneration of shoots， and then restores root growth and development， thereby synergistically promoting the rapid regeneration of sweet sorghum.

Impact of high temperature on soil water， heat and salt in purple paddy fields under different tillage patterns

Zhong-yi YIN, Li-hua MA, Zhao-lei LI, Hua FENG, Xian-jun JIANG

2024, 33(5):  80-91.  DOI: 10.11686/cyxb2023229

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High-temperature events occurred more frequent in recent years than before in southwest China. The high temperature increases the soil temperature in paddy fields， and this has affected the paddy fields habitat. The aim of this study， therefore， was to explore the impact of high temperature on soil water， heat， and salt in purple paddy fields， and to compare the responses of paddy fields with different tillage patterns to high temperature. Three tillage patterns including ridge tillage （RT）， conventional paddy-upland rotation tillage （CT）， and flooded paddy field （FPF） were selected to carry out this study. The soil temperature， soil water content， and soil conductivity were monitored in 0-10 cm， 10-20 cm， 20-40 cm， and 40-60 cm soil horizons in 2021 and 2022. It was found that there was no significant difference among the three different tillage patterns in soil temperature （P>0.05） in the 0-40 cm soil horizon under the non-high-temperature conditions， but there were significant differences in soil water content and soil conductivity. Under high-temperature conditions， soil temperature and soil water content differed significantly among the four soil horizons （P<0.05） and among the three different tillage patterns in paddy fields. The tillage patterns were ranked， from highest soil temperature and soil water content to lowest， as follows： RT>FPF>CT， and from highest soil conductivity to lowest as follows： CT>FPF>RT. Under both non-high-temperature conditions and high-temperature conditions， the soil temperature and soil conductivity were significantly positively correlated under all three tillage patterns. Our results showed that high temperature affected the relationships among soil temperature， soil conductivity， and soil water content. Under high-temperature conditions， the highest soil water content and lowest soil conductivity were in the RT paddy field， indicating that ridge tillage results in better adaptability of paddy fields to high-temperature conditions.

Effects of alfalfa/sweet sorghum intercropping on rhizosphere soil characteristics and microbial community characteristics

Sheng-ran HE, Xiao-jing LIU, Ya-jiao ZHAO, Xue WANG, Jing WANG

2024, 33(5):  92-105.  DOI: 10.11686/cyxb2023219

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In this study， we explored the influence of an alfalfa （Medicago sativa）/sweet sorghum （Sorghum dochna） intercropping system on the microecological environment of soil in the rhizosphere. The overall aims of our research were to provide a scientific and theoretical basis for improving soil structure， maintaining a good soil microecological environment， and protecting the ecological value of agricultural land. A 3-year field study was conducted with alfalfa and sweet sorghum grown as monocrops and in an intercropping system. We evaluated nodulation and nitrogen fixation， rhizosphere soil nutrient contents， soil enzyme activities， and the soil microbial community characteristics and their interrelationships over 3 consecutive years. The results showed that Proteobacteria， Bacteroidetes， and Bacillus were the dominant bacteria in the alfalfa/sweet sorghum intercropping system. Intercropping effectively increased the relative abundance of Bacteroidetes， Proteobacteria， Actinobacteria， and Gp6 in the rhizosphere soil， significantly increased soil organic matter and available phosphorus contents， and increased urease activity and invertase activity in the rhizosphere soil of sweet sorghum （P<0.05）. Intercropping also significantly increased nitrogenase activity and the nitrogen-fixation capacity （P<0.05）， and significantly reduced the rhizosphere soil pH of both alfalfa and sweet sorghum （P<0.05）. The activities of alkaline phosphatase and invertase increased in the rhizosphere soil of intercropped alfalfa over the 3 years， and the pH of rhizosphere soil decreased significantly over the 3 years in both monocrops and in the intercropping system （P<0.05）. The results of the correlation analysis indicated that four rhizosphere soil enzymes were positively correlated with available nitrogen， available potassium， and organic matter （P<0.01）； Proteobacteria and Bacteroidetes were negatively correlated with pH and positively correlated with available nitrogen； and Acidobacteria and Verrucomicrobia were positively correlated with pH and negatively correlated with available nitrogen （P<0.01）. Therefore， alfalfa/sweet sorghum intercropping was shown to improve the soil structure and increase the activity of soil microorganisms.

Biological characteristics and plant growth-promoting and biocontrol properties of endophytic bacterium ZJ1 from Buddleja lindleyana

Xiao-lu ZOU, Wen-jing ZHANG, Hong LYU, Nan QIN, Xiao-jun ZHAO, Hui YIN, Lu REN

2024, 33(5):  106-114.  DOI: 10.11686/cyxb2023223

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The objective of this study was to promote the application of biological control technology in a practical setting. As determined by the dilution coating plate method， the lethal temperature for ZJ1 was 96 ℃ for 20 min and the lethal pH was ≤4 or ≥14. Biofilm can absorb metal ions in soil to improve the plant growth environment， and can help biocontrol strains to colonize the surface of plants and exert their biocontrol functions. The effect of several common metal ions on the biofilm formation of ZJ1 was evaluated using a bacterial membrane detection method. It was found that the biofilm production of ZJ1 was inhibited by 0.3% Zn²⁺， Mn²⁺， Cu²⁺， and Fe²⁺， but promoted by 0.3% Mg²⁺ or K⁺. The biofilm formation ability of ZJ1 was further measured using a quantitative 96-well microplate method， and the results showed that ZJ1 was a strong biofilm-forming strain. The results of an indoor pot experiment showed that the protective effect of a 10-fold dilution of ZJ1 fermentation broth on tomato early blight was up to 95.54%， and the therapeutic effect of a 200-fold dilution of ZJ1 fermentation broth on tomato gray mold was up to 91.99%. Considering the therapeutic and protective effects of ZJ1 against these two disease-causing organisms， the 200-fold dilution of ZJ1 fermentation broth had the best control effect. The fermentation broth of ZJ1 at 10-fold to 200-fold dilution also had a growth-promoting effect on tomato plants. Therefore， strain ZJ1 is a microbial strain with biocontrol potential.

Functional gene abundance and community diversity of ammonia-oxidizing and denitrifying microorganisms in the rhizosphere soil of desert leguminous shrubs

Shuang LIU, Jia-ni YAO, Jun-jie ZHANG, Jin-xia DAI

2024, 33(5):  115-127.  DOI: 10.11686/cyxb2023239

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The aim of this study was to explore the patterns of functional gene abundance and community composition of microorganisms involved in ammonia oxidation and denitrification in rhizosphere soil of leguminous shrubs on the Ningxia desert steppe among different plant types and growth periods. We collected rhizosphere soil samples from typical leguminous shrub communities in the Baijitan National Nature Reserve of Ningxia， including Caragana korshinskii， Ammopiptanthus mongolicus， Oxytropis aciphylla， and Caragana tibetica at different growth stages （vegetative， flowering， and fruiting stages）. Using real-time quantitative PCR and high-throughput sequencing methods， the abundance of functional genes and the characteristics of community structure of ammonia-oxidizing and denitrifying microorganisms in rhizosphere soil of four shrubs， as well as their correlations with soil factors， were analyzed. It was found that the abundance of functional genes and community structure varied among different shrub types and growth periods. The abundance of functional genes was significantly higher in the rhizosphere soil of C. korshinskii than in the rhizosphere soil of the other shrubs， and reached the highest level during the flowering period. The diversity of the ammonia-oxidizing bacteria （AOB） community in the rhizosphere soil of C. korshinskii at different growth periods was higher than that of the AOB communities in the rhizosphere soils of the other shrub types， while the diversity of ammonia-oxidizing archaea （AOA） and nirK-type denitrifying bacteria communities was lowest in the rhizosphere soil of C. tibetica. Unclassified taxa were the predominant AOA in rhizosphere soil of each shrub with an extremely high abundance of 79.34%-98.37%， whereas Thaumarchaeota and Crenarchaeota only accounted for 0.28%-20.37% and 0.28%-2.35%， respectively. Proteobacteria was the dominant phylum of AOB in the rhizosphere of C. korshinskii， while Norank_d__Bacteria was the dominant AOB in the rhizosphere soil of the other plants. Both nirK- and nirS- type denitrifying bacteria were dominated by Proteobacteria， but the composition of nirK- type denitrifying bacteria was more significantly influenced by the plant type and growth period. The abundance of functional genes was significantly positively correlated with soil total nitrogen， available potassium， and pH. The soil total potassium， available potassium， and organic matter significantly affected the community composition of ammonia-oxidizing microorganisms， and pH was the main factor affecting the community structure of denitrifying microorganisms.

Functional analysis of the R2R3-MYB transcription factor CiMYB4 of Chrysanthemum indicum var. aromaticum in response to cadmium stress

Qiang LI, Fan KANG, Qing XUE, Bin CHEN, Ying SUN

2024, 33(5):  128-142.  DOI: 10.11686/cyxb2023236

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The aim of this study was to explore the role of CiMYB4 in the response to cadmium stress. In hydroponic experiments， wild-type （WT） plants and CiMYB4-overexpressing tobacco （Nicotiana tabacum） （CiMYB4-S） and chrysanthemum （Chrysanthemum indicum） （CiMYB4-OE） as well as chrysanthemum with RNAi-silenced CiMYB4 （CiMYB4-Ri） were subjected to cadmium treatments. Growth-related indexes， antioxidant enzyme activities， photosynthetic indexes， cadmium contents in above-ground and roots， and the transcript levels of cadmium tolerance-related genes （PCS1， GSH1， ABCC1， and HMA3） were determined.After cadmium treatments， compared with WT， CiMYB4-S and CiMYB4-OE showed significantly greater root length， stem diameter， plant height， leaf length， and leaf width； showed lower malondialdehyde content and higher superoxide dismutase activity， peroxidase activity， and catalase activity， higher values for photosynthetic parameters； and showed significantly increased chlorophyll content， stronger cadmium enrichment and transport， and significantly higher transcript levels of PCS1， GSH1， and HMA3. In contrast， compared with WT， CiMYB4-Ri had significantly lower plant height and above-ground dry weight； higher malondialdehyde content， lower superoxide dismutase， peroxidase， and catalase activities， lower photosynthetic parameter values； significantly lower chlorophyll content； reduced cadmium enrichment and transport ability； and significantly lower transcript levels of PCS1， GSH1， and HMA3. These results indicate that CiMYB4 is involved in the response to cadmium stress， and its overexpression in transgenic tobacco and chrysanthemum can significantly improve their cadmium tolerance.

Identification and transcript profiling of the CAMTA gene family under abiotic stress in alfalfa

Hai-ming KONG, Jia-xing SONG, Jing YANG, Qian LI, Pei-zhi YANG, Yu-man CAO

2024, 33(5):  143-154.  DOI: 10.11686/cyxb2023240

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Calmodulin-binding transcription activating factors （CAMTA） are calmodulin-binding proteins that play important roles in hormone signal transduction， developmental regulation， and environmental stress tolerance. In this study， bioinformatic methods were used to identify members of the CAMTA family in alfalfa （Medicago sativa） based on the reference genome of M. sativa “XinjiangDaye”. A phylogenetic analysis was conducted to evaluate relationships among the MsCAMTA genes. The physicochemical properties and conserved domains of the putative proteins were determined. The chromosomal positions of MsCAMTA genes were mapped， and cis-acting elements were identified in their promoter regions. The transcriptional profiles of MsCAMTA genes under various stress conditions were analyzed and validated. Seventeen MsCAMTA genes were identified， and the MsCAMTA family members grouped into three subfamilies in the phylogenetic analysis. Members of the same subfamily had relatively similar gene structures and positions of conserved motifs. The chromosomal localization results showed that members of the MsCAMTA family were unevenly distributed on seven chromosomes. A large number of cis-acting elements that respond to low temperature， salt stress， and plant hormone signals were identified in the promoter regions of these genes. We conducted RT-qPCR analyses to determine the transcript levels of MsCAMTA1， MsCAMTA3， MsCAMTA11， and MsCAMTA12 in alfalfa leaves under salt （300 mmol·L^-1 NaCl）， simulated drought （400 mmol·L^-1 mannitol）， low temperature （10 ℃）， and abscisic acid （100 μmol·L^-1） treatments. All four MsCAMTA candidate genes responded to various stressors to varying degrees. All four were up-regulated under salt stress. The results suggested that MsCAMTA may participate in the responses of alfalfa to various abiotic stresses by integrating multiple stress signals. The results of this study provide a reference for further studies on the functions of MsCAMTA genes in plant response to stress.

Effects of low-concentrate and high-concentrate diets on yak growth performance and rumen microbiota structure

Di SHEN, Zi-ming ZENG, Kai-yue PANG, Sha-tuo CHAI, Hong-xin NIE, Yu-min LI, Yang LIAO, Xun WANG, Wei-hua HUANG, Shu-jie LIU, Ying-kui YANG, Shu-xiang WANG

2024, 33(5):  155-165.  DOI: 10.11686/cyxb2023238

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The objective of this study was to determine the effects of low- and high-concentrate diets on the rumen microbiota in yaks. Twelve 3-year-old yaks with similar body weight were selected and divided into two groups of six. One group was fed with a low-concentrate diet ［30∶70 fine-to-rough ratio （C₃₀ group）］ and the other was fed with a high-concentrate diet ［70∶30 （C₇₀ group）］ for 2 months. It was found that： 1） The average daily weight gain of the C₇₀ group was significantly higher than that of the C₃₀ group （P<0.01）. 2） The Chao1 index， Shannon index， and phylogenetic diversity index were significantly higher for the C₃₀ group than for the C₇₀ group （P<0.01）. 3） At the phylum level， the relative richness of Patescibacteria， Desulfobacterota， Verrucomicrobia， and Cyanobacteria in the rumen was significantly higher in the C₃₀ group than in the C₇₀ group （P<0.05）. The relative richness of Firmicutes in the rumen was significantly higher in the C₃₀ group than in the C₇₀ group （P<0.01）. The relative richness of Bacteroides in the rumen was significantly higher in the C₇₀ group than in the C₃₀ group （P<0.01）， and that of Proteobacteria was significantly higher in the C₇₀ group than in the C₃₀ group （P<0.05）. At the genus level， the relative richness of Christensenellaceae_R-7， unclassified_rumen_bacterium， NK4A214_group， uncultured bacteria， and unidentified bacteria in the rumen was significantly higher in the C₃₀ group than in the C₇₀ group （P<0.01）. The Rikenellaceae_RC9_gut_group in the C₃₀ group was significantly higher than that in the C₇₀ group （P<0.05）. The relative richness of Prevotella， Lachnospiraceae_NK3A20_group and Ruminococcus in the C₇₀ group was significantly higher than that in the C₃₀ group （P<0.05）. 4） There were 31 gene families identified across all yak rumen samples. At KEGG level 2， pathways of transport and catabolism， cofactor and vitamin metabolism， and energy metabolism were significantly enriched in the C₇₀ group compared with the C₃₀ group （P<0.05）. The carbohydrate metabolism pathway was highly significantly enriched in the C₇₀ group compared with the C₃₀ group （P<0.01）. The immune disease pathway was enriched in the C₃₀ group compared with the C₇₀ group， and the biosynthesis of other secondary metabolites pathway was also very highly enriched in the C₇₀ group compared with the C₃₀ group （P<0.01）. In summary， high concentrate was fed compared to the low concentrate group the diet reduced the diversity of rumen microbiota in yak and reduced the richness of microflora that was not conducive to rumen microbiota health， while increasing the abundance of dominant microflora Richness. In terms of metabolic function， the high-concentrate diet increased the metabolism of carbohydrates and other nutrients， and decreased the metabolism of immune diseases.

Advances in research on the interactions among arbuscular mycorrhizal fungi， rhizobia， and plants

Hai-xia DUAN, Qian SHI, Sheng-ping KANG, Hai-qing GOU, Chong-liang LUO, You-cai XIONG

2024, 33(5):  166-182.  DOI: 10.11686/cyxb2023225

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Arbuscular mycorrhizal fungi （AMF） and rhizobia play crucial roles in plant productivity， microbial community structure， and soil quality. As such， they are key organisms for achieving sustainable ecosystem development. Over time， a mutually beneficial symbiotic relationship develops between AMF and rhizobia， and this relationship is essential for effective biological nitrogen fixation and nutrient absorption. Such effective symbioses reduce reliance on chemical fertilizers， thereby facilitating sustainable agricultural practices. However， studies have shown that various environmental factors can hinder the formation of symbiotic relationships between AMF and rhizobia. Therefore， it is necessary to systematically explore the mechanism of the AMF-rhizobia interaction and the factors that affect it. On the basis of a literature review and qualitative comparative analysis， we described the process and mechanism by which plant roots released exudates to stimulate rhizobia and AMF to produce nodulation factors and mycorrhizal factors， thereby activating signaling pathways involved in the establishment of symbiotic relationships between rhizobia-AMF and plants. This review summarized the results of research on the synergism and interaction between AMF-rhizobia and plants， and the biological and abiotic factors affecting the AMF-rhizobia symbiosis and interactions. We highlighted the current gaps in knowledge related to the mechanisms of the symbiotic relationships among AMF， rhizobia， and plants， and discussed the reasons for the slow development of microbial fertilizers. Finally， we discussed future research directions at the theoretical， technical， and application levels. Further research will provide novel ideas and methods for using AMF and rhizobia to promote sustainable agricultural development.

Variations in soil inorganic nitrogen content under canopies of two shrubs in the Junggar Desert

Si-yao PAN, Yu-chuan SONG, Ru-yi YUAN, Sheng-tong HOU, Jun-ge CAI, Bing CHEN, Jun-hui CHENG

2024, 33(5):  183-195.  DOI: 10.11686/cyxb2023232

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As a direct nitrogen source for plant absorption and utilization， the soil inorganic nitrogen content （SINC） reflects the nitrogen-supply capacity of soil. Many studies have revealed that in desert ecosystems， SINC is significantly affected by the shrub species， but also by the position of the sampling site. However， there is still limited knowledge about the impact of sampling direction on SINC. In this study， we selected two dominant shrubs （Haloxylon ammodendron and Kalidium caspicum） that are widely distributed in the Junggar Desert， and collected soil samples at 0-10 cm and 10-20 cm soil depths under plants in four size classes （large， medium， small， and very small） at four spatial positions （shrub center， shrub middle， shrub edge， and shrub outside） and for four sampling directions （east， south， west and north）. We then measured the nitrate nitrogen content （NNC） and ammonium nitrogen content （ANC） in the soil samples， and calculated the ratio of ammonium nitrogen content （RAN） to nitrate nitrogen. These analyses allowed us to determine the main and interactive effects of shrub size， spatial position， and sampling direction on SINC. It was found that： 1） Shrub size significantly affected SINC. In particular， NNC was higher under canopies of large individuals than under canopies of smaller individuals of both H. ammodendron and K. caspicum. However， ANC and RAN were lowest under canopies of large individuals of H. ammodendron but highest under canopies of large individuals of K. caspicum， suggesting that the variation in SINC was dependent on shrub size. 2） NNC and ANC were significantly higher in the 0-10 cm soil depth than in the 10-20 cm soil depth under canopies of H. ammodendron and K. caspicum， indicating that shrubs had a stronger effect on SINC in the topsoil layer. 3） SINC under canopies of H. ammodendron was affected by interactive effects between shrub size and sampling direction， and a SINC enrichment phenomenon was observed at the east and south directions under canopies of H. ammodendron. 4） SINC under canopies of K. caspicum was influenced by the interactive effect between spatial position and sampling direction. SINC was generally higher at the shrub center that at the other three positions at the east and south directions. These findings demonstrate that in desert ecosystems， SINC under shrub canopies varies among shrub species and is affected by shrub size， spatial position， and sampling direction.

Evaluation and identification of salt tolerance of 11 Leonurus germplasm lines at the seedling stage

Chen MENG, Xue-li LU, Yi-ru SONG, Cheng-sheng ZHANG, Yi-qiang LI, Hai-qin XIANG, Zong-chang XU

2024, 33(5):  196-203.  DOI: 10.11686/cyxb2023218

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Soil salinization is one of the main factors restricting agricultural development in China. The use of medicinal plants for biological improvement of saline alkali land is an effective means of resource utilization of it. In this study， 11 Leonurus heterophyllus materials were treated with 2% w/v NaCl at the seedling stage to impose salt stress， and 12 indexes including plant height， root length， leaf area， above-ground fresh weight， and root fresh weight were measured. Multivariate statistical analysis methods such as principal component analysis and membership function analysis were used to evaluate the salt tolerance of each sample. The results showed that there were significant differences in various indexes of L.heterophyllus， with the coefficient of variation ranging from 13.58% to 59.89%. The four indexes of the above-ground fresh weight， above-ground dry weight， root fresh weight， and leaf area were greatly affected by salt stress， and there were varying degrees of correlation among the 12 indexes. Chlorophyll content， main root diameter， dry and fresh weight of above-ground parts as well as dry and fresh weight of roots were identified as indicators for evaluating the salt tolerance of L.heterophyllus at the seedling stage. Based on the salt tolerance score and the comprehensive evaluation of salt tolerance， HY199 and HY203 were identified as the most salt-tolerant L.heterophyllus. The above results provide theoretical guidelines for the cultivation of L.heterophyllus in saline-alkali areas.

Cloning and tissue-specific expression patterns of a gene encoding an atypical odorant receptor co-receptor in the leaf beetle Diorhabda rybakowi （Coleoptera： Chrysomelidae）

Bo-xin XI, Xiao-ning CUI, Su-qin SHANG, Gui-xin HU, Yan WANG, Chang-ning LI, Bin PENG, Xue-qiang SHI

2024, 33(5):  204-215.  DOI: 10.11686/cyxb2023265

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The leaf beetle Diorhabda rybakowi is one of the most important insect pests causing serious damage to the pioneer plant Nitraria spp.， which has windbreak and sand-fixation functions in the desert grasslands of Northwest China. The development and utilization of a chemical method based on insect perception of sex pheromones or host volatiles is a promising pest control strategy. In this study， we obtained an atypical odorant receptor co-receptor （Orco） gene sequence from the antennae of D. rybakowi adults using a molecular cloning method. We predicted the tertiary structure of the DrybOrco protein using homology modeling， constructed a phylogenetic tree， and detected the transcript levels of the DrybOrco gene in different tissues of male and female adults by real-time fluorescence quantitative PCR. It was found that the DrybOrco full-length gene sequence was 1918 bp long， with an open reading frame of 1440 bp encoding 479 amino acids. The putative protein had a predicted molecular weight of 53.94 kD， contained seven transmembrane domains， and was a hydrophobic membrane protein.The phylogenetic analysis revealed high conservation of Orco genes among 68 species of insects in six different orders （similarity >68%）. In the phylogenetic tree， these genes grouped into three branches， with genes from the same insect order clustered on the same branch. The DrybOrco genewas clustered on the branch with sequences from other coleoptera species， and showed the highest nucleotide sequence similarity （92.28%） to the gene from Diabrotica virgifera. The qRT-PCR results showed that there were high transcript levels of the DrybOrco gene in the adult antennae， and with significantly higher levels （2.27 times higher） in the antennae of males than in the antennae of females. Low levels of DrybOrco transcripts were also detected in the legs of male adults and the wings of female adults， but its transcripts were barely detectable or absent from the other sampled tissues. The results of this study reveal the sequence characteristics and transcript profiles of an Orco gene in D. rybakowi adults， and details of the structure and characteristics of the putative protein. These findings provide a theoretical basis for elucidating the physiological function of the DrybOrco protein in chemosensory processes， and for further detailed studies on the olfactory molecular mechanism of host specialization in D. rybakowi.