NaCl胁迫下外源壳聚糖对菜用大豆光合作用及叶绿体活性氧代谢的影响

采用蛭石栽培,以菜用大豆为试材,研究外源壳聚糖对NaCl胁迫下幼苗叶片光合作用及叶绿体活性氧(ROS)代谢的影响,以期探明NaCl胁迫下壳聚糖调控菜用大豆光合作用的生理机制。结果显示:NaCl胁迫下,外源壳聚糖通过诱导非气孔因素显著缓解了菜用大豆在胁迫中期(第6~12天)净光合速率(Pn)的下降;外源壳聚糖显著抑制了叶绿体O-·2的产生速率及H2O2含量的上升,显著提高了超氧化物歧化酶(SOD)、过氧化物酶(POD)、谷胱甘肽还原酶(GR)活性及抗坏血酸过氧化物酶(APX)在胁迫中期(第6~12天)的活性。无盐条件下,外源壳聚糖在处理早期对上述各指标产生了显著影响,中、后期该作用消失。上述结果表明:外源壳聚糖在NaCl胁迫下对菜用大豆的作用与无盐条件下不同;NaCl胁迫下,壳聚糖可诱导菜用大豆叶绿体保护酶活性及As A-GSH循环的运转速率,及时清除过量ROS,以抑制盐胁迫对光合膜的伤害,这可能是壳聚糖缓解Pn下降,进而缓解菜用大豆干质量下降的重要原因之一;外源壳聚糖的作用具有时效性。

Effects of Exogenous Chitosan on Photosynthesis and Chloroplast Reactive Oxygen Species Metabolism of Vegetable Soybean under NaCl Stress

In order to investigate the mechanism of chitosan on regulating photosynthesis under NaCl stress,the effects of exogenous chitosan on photosynthesis and chloroplast active oxygen metabolism in seedling leaves of vege-table soybean under NaCl stress were studied by adopting vermiculite culture.The results showed that exogenous ch-itosan alleviated the decline of net photosynthetic rate (Pn)markedly at the 6th,9th and 12th days of salinity by in-ducing non stomatal factors under NaCl stress.Exogenous chitosan significantly decreased chloroplast O-· 2 production rate and H2 O2 contents,and increased the activities of superoxide dismutase (SOD),peroxidase (POD),glutathione reductase (GR)markedly,meanwhile the ascorbate peroxidase (APX)activity during the mid-term (the 6th to 12th day)of NaCl stress also was increased.Under salt free conditions,exogenous chitosan had significant effects on the above indexes in the early stage of treatment,but the effect disappeared in the mid and late period.The results indicated that the effects of exogenous chitosan under NaCl stress were different to those of salt free conditions;Chi-tosan induced the protective enzyme activity and the running rate of AsA-GSH cycle of soybean chloroplast and then removed excess reactive oxygen species in time so that inhibit the damage of the photosynthetic membrane.This might be the main reason for chitosan alleviate Pn decreasing,and then alleviate the decline in the dry weight of vegetable soybean;The effect of exogenous chitosan was time-sensitive.