外源H_(2)S缓解小麦苗期干旱胁迫的生理生化基础

Physiological and biochemical basis of exogenous H_(2)S alleviating drought stress in wheat seedling

小麦是人类重要的粮食作物之一,而其生长发育过程常受干旱胁迫,致使减产降质.随着全球气候变化,极端天气频发,小麦受旱面积与旱灾程度正逐年加剧.探究小麦抗旱调控机制,增强小麦抗旱能力,对于缓解小麦干旱胁迫造成的减产降质具有重要意义.前期研究发现低浓度的H_(2)S可显著缓解小麦幼苗干旱胁迫.笔者以20%聚乙二醇(PEG-6000)模拟中度干旱胁迫处理水培百农207小麦幼苗,以1 mmol·L^(-1)NaHS为H_(2)S供体对小麦幼苗进行叶面喷施处理,研究结果表明,干旱胁迫条件下,与未喷施NaHS的干旱处理组相比,外源喷施NaHS 7 d时可显著缓解干旱胁迫对小麦幼苗生长的抑制效应,主要表现在:株高和根长分别显著增加9.63%和19.7%;地上部分及地下部分干重分别显著增加17.63%和12.58%;内源H_(2)S显著增加了43.76%;光合效率显著增加了3.02%;超氧化物歧化酶、过氧化物酶和抗坏血酸过氧化物酶的活性分别显著增加了13.83%,11.57%,41.87%;丙二醛和过氧化氢的含量显著降低了36.1%和65.72%;脯氨酸显著增加了48.22%;酸性磷酸酶及碱性磷酸酶活性分别显著增加了62.87%及22.03%.因此,干旱胁迫下叶面外源喷施NaHS缓解了小麦幼苗的形态学指标及光合生理性能的下降,增强了抗氧化能力及渗透调节能力,提升了小麦应对干旱胁迫的能力,与此同时,干旱胁迫下外源喷施NaHS提升了小麦幼苗酸性磷酸酶及碱性磷酸酶的活性水平.以上结果为进一步探究外源H_(2)S缓解小麦干旱胁迫的磷酸酶分子调控机制奠定基础.

Wheat is one of the important food crops for mankind,and its growth and development are often under drought stress,which reduces wheat yield and quality.Understanding the mechanism of wheat drought resistance to enhance the drought resistance ability of wheat is of great significance in alleviating the reduction of wheat yield and quality caused by drought stress.The authors’previous study found that low concentration of H_(2)S could significantly alleviate wheat seedings drought stress.In this paper,20%polyethylene glycol(PEG-6000)was used to simulate moderate drought stress to treat hydroponic Bainong 207 wheat seedlings,and 1 mmol·L^(-1)NaHS was used as H_(2)S donor to spray wheat seedlings.The results showed that under drought stress conditions,compared with the non-sprayed NaHS treatment group,exogenous spraying of NaHS could significantly alleviate the inhibitory effect of drought stress on the growth of wheat seedlings,which was shown as:the plant height and root length significantly increased by 9.63%and 19.70%,respectively;the dry weight and fresh weight of the above-ground and underground parts significantly increased 17.63%and 12.58%,respectively;the content of endogenous H_(2)S increased by 43.76%;photosynthetic efficiency increased by 3.02%;the enzymatic activities of superoxide dismutase,peroxidase and ascorbate peroxidase increased by 13.83%,11.57%and 41.87%,respectively;the contents of malondialdehyde and hydrogen peroxide were significantly reduced by 36.10%and 65.72%,respectively;proline significantly increased by 48.22%;acid phosphatase and alkaline phosphatase activities increased by 62.87%and 22.03%,respectively.Therefore,exogenous spraying of NaHS under drought stress alleviated the morphological and photosynthetic indicators of wheat seedlings,enhanced the antioxidant capacity and osmotic adjustment capacity,and improved the ability of wheat to cope with drought stress;at the same time,under drought stress exogenous spraying of NaHS increased the activity levels of acid phosphatase and alkaline phosphatase in wheat seedlings.The above results lay the foundation for further exploring the molecular mechanism of phosphatase that exogenous H_(2)S alleviates wheat drought stress.