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Acta Prataculturae Sinica ›› 2018, Vol. 27 ›› Issue (11): 95-105.DOI: 10.11686/cyxb2017504

• Orginal Article • Previous Articles     Next Articles

Responses of photosynthetic physiological traits in transgenic alfalfa expressing multi-functional genes during soil moisture change

LI Min1, SU Guo-xia1, XIONG Pei-feng1, KANG Ji-yue2, KWAK Sang-soo3, WANG Zhi1, 2, *, XU Bing-cheng1, 2, *   

  1. 1.State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Northwest A&F University, Yangling 712100, China;
    2.Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, Yangling 712100, China;
    3.Plant Systems Engineering Research Center, Korea Research Institute of Biotechnology and Biotechnology, Daejeon 305-806, Korea
  • Received:2017-12-13 Revised:2018-03-28 Online:2018-11-20 Published:2018-11-20

Abstract: The photosynthetic and fluorescence characteristics of alfalfa (cv. Xinjiang Daye) and four transgenic lines (SN: transgenic AtNDPK2, SC: transgenic codA, SOR: transgenic IbOr, SAF: transgenic AtABF3) at the early flowering stage were investigated and compared under different soil moisture conditions in a pot experiment. Results showed that the net photosynthetic rate (Pn), transpiration rate (Tr) and stomatal conductance (Gs) of all lines showed a decreasing trendas soil moisture decreased from 80% FC (field capacity) to 40% FC, while instantaneous water use efficiency (WUEi) exhibited an increasing trend. At 40% FC, Pn values of transgenic lines were 11.19-21.58 μmol·m-2·s-1, significantly (P<0.05) higher than that of non-transgenic (NT) plants (6.06 μmol·m-2·s-1). There were no differences in WUEi among all alfalfa lines and the SAF line had the highest value (3.22 μmol·mmol-1). As soil moisture decreased, the initial fluorescence (Fo), maximum photochemical efficiency (Fv/Fm) and photochemical quenching coefficient (qP) values exhibited declining trends, and actual photochemical efficiency (ΦPSⅡ) and apparent electron transfer efficiency (ETR) values initially increased and then declined, while non-photochemical quenching coefficient (NPQ) values showed an increasing trend.The qP values of transgenic lines decreased significantly at 50% FC, while that of NT was 70% FC. Under 40% FC, Fv/Fm values of transgenic lines were 0.78-0.82, and were significantly higher than that of NT (0.58). This suggests that the expression of multi-functional genes could improve photosynthetic properties of Xinjiang Daye to some extent and that transgenic codA is able to sustain a high photosynthetic rate, transgenic IbOr line can maintain higher light use ability, transgenic AtABF3 is able to utilize water more efficiently, while transgenic AtNDPK2 had the highest total biomass production with decreasing soil moisture.

Key words: multi-functional gene, alfalfa, drought stress, photosynthetic characteristics, fluorescence parameter