Effects of exogenous melatonin on photosynthetic carbon assimilation and endogenous hormones in tobacco seedlings under drought stress

doi:10.11686/cyxb2020070

Abstract

Abstract:

In order to elucidate the physiological mechanism of exogenous melatonin （MT） application in relieving drought stress on tobacco seedlings growth. The drought-tolerant variety ‘Yuyan No.6’ and drought-sensitive variety ‘Yuyan No.10’ were tested for their response following foliar-spraying with MT at concentration of 0.2 mmol·L^-1 under normal water supply and drought stress. Parameters measured included seedlings growth， chlorophyll fluorescence parameters， photosynthetic carbon assimilation enzyme activity， and the contents of carbohydrates and endogenous hormones of the tobacco seedlings. The results showed that drought stress significantly inhibited the seeding growth of both tobacco cultivars， and the inhibiting effects in drought-sensitive ‘Yuyan No.10’ were greater than that in drought-tolerant ‘Yuyan No.6’. Exogenous melatonin application remarkably increased plant height， stem diameter， biomass， reduced the root-shoot ratio， increased maximal PSⅡ quantum yield （F_v/F_m）， PSⅡ actual photochemical efficiency （Φ_PSⅡ） and photochemical quenching coefficient （qP）， decreased non-photochemical quenching coefficient （NPQ）， enhanced the activities of sedoheptulose-1，7-bisphosphatase （SBPase） and ribulose-1，5-bisphosphate carboxylase （Rubisco）， and increased the contents of soluble total sugar， sucrose， fructose， auxin （IAA）， gibberellin （GA） and zeatin nucleoside （ZR）， reduced the contents of starch and abscisic acid （ABA） of tobacco seedlings under drought stress. The changes in drought-sensitive ‘Yuyan No.10’ were greater than those in drought-tolerant ‘Yuyan No.6’. The results indicated that exogenous MT played an important role on enhancing the activity of photosynthetic carbon assimilation enzyme， regulating the metabolism of endogenous hormones and carbohydrates， relieving the damage of photosynthetic apparatus caused by drought stress， and strengthening the drought resistance of tobacco seedlings.

Key words: melatonin, drought stress, tobacco seedlings, photosynthetic carbon assimilation enzyme, endogenous hormones, carbohydrates

Dong LI, Hong-tao SHEN, Yan-fang WANG, Yue-hua WANG, Li-jun WANG, Shi-min ZHAO, Ling LIU. Effects of exogenous melatonin on photosynthetic carbon assimilation and endogenous hormones in tobacco seedlings under drought stress[J]. Acta Prataculturae Sinica, 2021, 30(1): 130-139.

Figures/Tables 5

References 39

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品种 Variety	处理 Treatment	株高 Plant height (cm)	茎粗 Stem diameter (cm)	地上部鲜重 Shoot fresh weight (g·plant^-1)	地下部鲜重 Root fresh weight (g·plant^-1)	地上部干重 Shoot dry weight (g·plant^-1)	地下部干重 Root dry weight (g·plant^-1)	根冠比 Root-shoot ratio （DW）
Y10	CK	4.33±0.13b	0.84±0.03a	34.25±0.54b	6.87±0.30a	4.02±0.09b	0.69±0.02a	0.17±0.01c
	MT	4.80±0.24a	0.86±0.01a	37.53±1.29a	6.97±0.40a	4.38±0.04a	0.70±0.03a	0.16±0.01c
	MD	2.78±0.11d	0.65±0.01c	9.75±0.59d	2.31±0.15c	1.07±0.06d	0.24±0.02c	0.22±0.02a
	MD+MT	3.40±0.14c	0.73±0.01b	16.39±0.37c	3.51±0.12b	1.90±0.03c	0.36±0.02b	0.19±0.01b
Y6	CK	13.65±0.75a	0.74±0.02a	24.53±0.87b	6.88±0.09a	3.15±0.05b	0.67±0.02a	0.21±0.01b
	MT	13.85±0.19a	0.77±0.01a	27.83±0.45a	6.85±0.18a	3.32±0.03a	0.67±0.04a	0.20±0.01b
	MD	10.75±0.22b	0.64±0.02b	10.89±0.32d	3.36±0.21c	1.55±0.03d	0.42±0.01c	0.27±0.01a
	MD+MT	11.05±0.21b	0.68±0.02b	15.95±0.43c	4.49±0.17b	2.04±0.03c	0.53±0.01b	0.26±0.01a

品种 Variety	处理 Treatment	株高 Plant height (cm)	茎粗 Stem diameter (cm)	地上部鲜重 Shoot fresh weight (g·plant^-1)	地下部鲜重 Root fresh weight (g·plant^-1)	地上部干重 Shoot dry weight (g·plant^-1)	地下部干重 Root dry weight (g·plant^-1)	根冠比 Root-shoot ratio （DW）
Y10	CK	4.33±0.13b	0.84±0.03a	34.25±0.54b	6.87±0.30a	4.02±0.09b	0.69±0.02a	0.17±0.01c
	MT	4.80±0.24a	0.86±0.01a	37.53±1.29a	6.97±0.40a	4.38±0.04a	0.70±0.03a	0.16±0.01c
	MD	2.78±0.11d	0.65±0.01c	9.75±0.59d	2.31±0.15c	1.07±0.06d	0.24±0.02c	0.22±0.02a
	MD+MT	3.40±0.14c	0.73±0.01b	16.39±0.37c	3.51±0.12b	1.90±0.03c	0.36±0.02b	0.19±0.01b
Y6	CK	13.65±0.75a	0.74±0.02a	24.53±0.87b	6.88±0.09a	3.15±0.05b	0.67±0.02a	0.21±0.01b
	MT	13.85±0.19a	0.77±0.01a	27.83±0.45a	6.85±0.18a	3.32±0.03a	0.67±0.04a	0.20±0.01b
	MD	10.75±0.22b	0.64±0.02b	10.89±0.32d	3.36±0.21c	1.55±0.03d	0.42±0.01c	0.27±0.01a
	MD+MT	11.05±0.21b	0.68±0.02b	15.95±0.43c	4.49±0.17b	2.04±0.03c	0.53±0.01b	0.26±0.01a

品种Variety	处理Treatment	F_v/F_m	Φ_PSⅡ	qP	NPQ
Y10	CK	0.827±0.009a	0.482±0.130a	0.691±0.015a	1.128±0.099c
	MT	0.825±0.005a	0.486±0.040a	0.681±0.013a	1.201±0.081c
	MD	0.791±0.004c	0.362±0.009c	0.529±0.015c	1.851±0.057a
	MD+MT	0.817±0.002b	0.421±0.005b	0.635±0.015b	1.507±0.041b
Y6	CK	0.831±0.001a	0.450±0.005a	0.646±0.011a	1.333±0.025bc
	MT	0.830±0.002a	0.468±0.009a	0.657±0.006a	1.235±0.039c
	MD	0.809±0.003c	0.414±0.006b	0.547±0.005c	1.678±0.026a
	MD+MT	0.829±0.004b	0.446±0.008a	0.604±0.007b	1.426±0.041b

品种Variety	处理Treatment	F_v/F_m	Φ_PSⅡ	qP	NPQ
Y10	CK	0.827±0.009a	0.482±0.130a	0.691±0.015a	1.128±0.099c
	MT	0.825±0.005a	0.486±0.040a	0.681±0.013a	1.201±0.081c
	MD	0.791±0.004c	0.362±0.009c	0.529±0.015c	1.851±0.057a
	MD+MT	0.817±0.002b	0.421±0.005b	0.635±0.015b	1.507±0.041b
Y6	CK	0.831±0.001a	0.450±0.005a	0.646±0.011a	1.333±0.025bc
	MT	0.830±0.002a	0.468±0.009a	0.657±0.006a	1.235±0.039c
	MD	0.809±0.003c	0.414±0.006b	0.547±0.005c	1.678±0.026a
	MD+MT	0.829±0.004b	0.446±0.008a	0.604±0.007b	1.426±0.041b

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