转多抗基因新疆大叶苜蓿光合生理特征对土壤水分变化的响应

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

以新疆大叶苜蓿及其为母本的4种转基因株系(SN:转AtNDPK2基因;SC:转codA基因;SOR:转IbOr基因;SAF:转AtABF3基因)为研究材料,通过盆栽控制试验,比较研究了不同土壤水分条件下始花期各株系苜蓿的光合和荧光参数特征。结果表明,随土壤含水量从80%FC(田间持水量)降至40%FC,各株系叶片净光合速率(Pn)、蒸腾速率(Tr)和气孔导度(Gs)均呈下降趋势,叶片瞬时水分利用效率(WUEi)呈上升趋势。在40%FC时,各转基因株系Pn值(11.19～21.58μmol·m^(-2)·s^(-1))均显著(P<0.05)大于非转基因株系(6.06μmol·m^(-2)·s^(-1)),各株系间WUEi无差异但以转AtABF3基因株系最大(3.22μmol·mmol^(-1))。土壤水分降低过程中,各株系叶片初始荧光(Fo),最大光化学效率(Fv/Fm)和光化学淬灭系数(qP)值总体呈下降趋势,实际光化学效率(ΦPSⅡ)和表观电子传递效率(ETR)值呈先上升后下降,而非光化学淬灭系数(NPQ)值整体呈上升趋势。转基因株系qP值出现显著下降时的土壤水分含量(50%FC)低于非转基因(70%FC)苜蓿。在40%FC时,转基因株系Fv/Fm(0.78～0.82)值显著高于非转基因苜蓿(0.58)。总体表明,转多抗基因均不同程度地提高水分胁迫条件下新疆大叶苜蓿的光合性能,其中转codA基因株系可维持较高光合速率,转IbOr基因株系能维持较高光能利用能力,转AtABF3基因株系能够高效利用水分,转AtNDPK2基因株系总生物量最高。

The photosynthetic and fluorescence characteristics of alfalfa(cv.Xinjiang Daye)and four transgenic lines(SN:transgenic AtNDPK 2,SC:transgenic codA,SOR:transgenic IbOr,SAF:transgenic AtABF 3)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(P n),transpiration rate(T r)and stomatal conductance(G s)of all lines showed a decreasing trendas soil moisture decreased from 80%FC(field capacity)to 40%FC,while instantaneous water use efficiency(WUE i)exhibited an increasing trend.At 40%FC,P n values of transgenic lines were 11.19-21.58μmol·m-2·s-1,significantly(P<0.05)higher than that of non-transgenic(NT)plants(6.06μmol·m-2·s-1).There were no differences in WUE i among all alfalfa lines and the SAF line had the highest value(3.22μmol·mmol-1).As soil moisture decreased,the initial fluorescence(F o),maximum photochemical efficiency(F v/F m)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,F v/F m 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 AtABF 3 is able to utilize water more efficiently,while transgenic AtNDPK 2 had the highest total biomass production with decreasing soil moisture.