Department of Chemistry and Biochemistry, Haryana Agricultural University, 125 004, Hissar, India.
Photosynth Res. 1985 Jan;7(1):69-76. doi: 10.1007/BF00032923.
Leaf water potential was decreased by withholding irrigation to provide three levels of stress described as mild ({ie69-1}) moderate ({ie69-2}) and severe ({ie69-3}). The specific activity of NADP linked glyceraldehyde-3-phosphate dehydrogenase, phosphoglycerate kinase, aldolase, phosphogluco-isomerase and RuBP carboxylase decreased under mild stress, but the activity of phosphoglucomutase showed an increase whilst ribulose-5-phosphate kinase was least affected. With further decrease in water potential, the activity of NADP linked glyceraldehyde-3-phosphate dehydrogenase and aldolase showed a decrease, whereas, the activities of fructose-1,6-bisphosphatase, phosphoglycerate kinase, phosphogulcomutase and RuBP carboxylase increased. Net CO2 fixation decreased sharply with stress, whereas, respiration and photorespiration increased in moderate stress, but decreased under severe stress. Stomatal resistance also increased with decrease in water potential. It seems that in vitro enzyme activities of PCR cycle are not responsible for decreased photosynthesis in pigeonpea under short term water stress.
叶片水势因控水而降低，由此产生三种胁迫水平，分别为轻度胁迫（{ie69-1}）、中度胁迫（{ie69-2}）和重度胁迫（{ie69-3}）。在轻度胁迫下，NADP 连接的甘油醛-3-磷酸脱氢酶、磷酸甘油酸激酶、醛缩酶、磷酸葡萄糖异构酶和 RuBP 羧化酶的比活下降，但磷酸葡糖变位酶的活性增加，而核酮糖-5-磷酸激酶的活性受影响最小。随着水势的进一步降低，NADP 连接的甘油醛-3-磷酸脱氢酶和醛缩酶的活性下降，而果糖-1,6-二磷酸酶、磷酸甘油酸激酶、磷酸葡糖变位酶和 RuBP 羧化酶的活性增加。净 CO2 固定随胁迫急剧下降，而在中度胁迫下呼吸和光呼吸增加，但在重度胁迫下下降。气孔阻力也随水势的降低而增加。看来，在短期水分胁迫下，PCR 循环的体外酶活性并不是导致鸽豆光合作用下降的原因。
