外源NO对铝胁迫下紫花苜蓿幼苗生长的影响

利用水培法研究外源NO对铝胁迫（0.1 mmol/L）下生长的紫花苜蓿（WL525HQ）幼苗形态、生理特征的影响,揭示NO缓解紫花苜蓿铝毒的生理机制。结果表明：铝胁迫抑制了幼苗的生长,表现为株高、根长、叶面积、地上和地下部生物量显著降低。另一方面,降低了叶片中脯氨酸含量和超氧化物歧化酶活性,提高了根系脯氨酸含量（P<0.05）。施用外源NO后,紫花苜蓿在形态和生理方面对铝胁迫的响应发生了一些改变,且改变与NO的浓度有关。其中,低浓度NO缓解了铝胁迫对苜蓿幼苗主根伸长的抑制作用;中浓度NO则解除了铝胁迫对株高、根系表面积和体积的抑制作用,提高了地上和地下部生物量;高浓度NO显著地提高了苜蓿地上部和地下部脯氨酸含量和SOD活性。综上所述,外源NO能通过积累脯氨酸、增加SOD活性等方式,缓解铝胁迫对紫花苜蓿幼苗生长的抑制作用,促进地上部和地下部的物质积累。

Impacts of Exogenous Nitric Oxide on Growth of Alfalfa Seedlings Exposed to Aluminum Stress

The effects of exogenous nitric oxide (NO) application on the morphological and physiological characteristics of alfalfa (WL525HQ) seedlings under aluminum stress (0.1 mmol/L) were studied through hydroponics to reveal the physiological mechanism of NO alleviating aluminum toxicity of alfalfa. The results indicated that aluminum stress inhibited the growth of alfalfa seedlings shown by the significant decrease in plant height, root length, leaf area, aboveground and belowground biomass. Free proline content and superoxide dismutase (SOD) activity in the leaves were significantly reduced, whereas proline in the roots was significantly increased (P<0.05). Exogenous NO application affected its morphological and physiological responses to aluminum stress, and it was related to the concentration applied. Low concentration of exogenous NO alleviated the inhibiting effect of aluminum stress on the main root length. Medium concentration increased plant height, surface area and volume of root system under aluminum stress, which led to increases of above and below ground biomass. High concentration significantly increased free proline and SOD activity. In summary, exogenous NO alleviates the inhibitory effect of aluminum stress on the growth of alfalfa seedlings through processes like free proline accumulation and SOD, hence, contribute to enhancement of above and below ground biomass.