With pot experiment, two soybean (Glycine max) varieties, Jindou 21 (drought-tole-rant) and Xudou 22 (drought-sensitive), were used to examine the effects of α-naphthaleneacetic acid (NAA) on carbon metabolism of soybean under drought stress at flowering stage. The results showed that under drought stress, compared to Xudou 22, Jindou 21 had smaller decrease in net photosynthetic rate (Pn), smaller increase in photorespiration rate (Pr) and soluble sugar content of leaves, while a greater increase in the activities of sucrose phosphate synthase (SPS) and sucrose synthetase (SS) (synthesis) of leaves and sucrose content of roots. NAA treatment increased Pn and decreased Pr under drought stress, and thus obviously alleviated the growth inhibition of drought stress on plants. NAA treatment reduced the activities of starch-degrading enzymes, acid invertase (AI) and SS (cleavage), thereby inhibited the accumulation of soluble sugar induced by drought stress. In addition, NAA treatment increased SPS and SS (synthesis) activities of leaves, sucrose content of roots and shoot-root ratio, indicating that NAA treatment improved the transportation of sucrose from leaf blade to root under drought stress. In conclusion, exogenous NAA could enhance drought tolerance in soybean by regulating carbon metabolism.
以耐旱性大豆品种晋豆21和干旱敏感性大豆品种徐豆22为试验材料,通过盆栽试验,研究α-萘乙酸(NAA)对花期干旱大豆碳代谢的影响.结果表明: 干旱胁迫下,与徐豆22相比,晋豆21净光合速率(Pn)下降幅度较小,光呼吸速率(Pr)和叶片可溶性糖含量增加幅度较小,而叶片蔗糖磷酸合成酶(SPS)、蔗糖合成酶(SS)(合成方向)活性、根系蔗糖含量增加幅度较大.NAA处理提高了干旱胁迫下Pn,并降低了Pr,进而明显缓解了干旱胁迫对大豆植株的生长抑制;降低了叶片淀粉分解酶、酸性转化酶(AI)和SS(分解方向)活性,从而抑制了干旱胁迫诱导的可溶性糖积累;NAA处理也能增加干旱胁迫下叶片SPS、SS(合成方向)活性、根系蔗糖含量、根冠比,表明NAA处理促进了叶片中蔗糖向根系的转运.总之,在干旱胁迫下,外源NAA能够通过调控碳代谢增强大豆植株对干旱胁迫的耐受性.
Keywords: carbon metabolism; drought stress; flowering stage; soybean; α-naphthaleneacetic acid (NAA).