一氧化氮对冬小麦抵抗臭氧胁迫的作用研究

Tropospheric ozone (O3) is currently considered as the most phytotoxic secondary air pollutant that influences plant productivity. With the rapid development of industrialization and urbanization in China, O3 concentration is gradually increasing. Although there have been numerous studies on the negative effects of elevated O3 concentration on crop growth and development, little has been known on how to relieve its influence on crops. As a major food crop in China, wheat (Triticum aestivum) is highly sensitive to ozone pollution. Our previous study has found that ozone enhanced the endogenous NO content of wheat leaves, and exogenous sodium nitroprusside (SNP) application could alleviate the damage of wheat. In the proposed project, two winter wheat cultivars will be fumigated by ozone in open top chambers. The project aims to reveal the mechanism of ozone-induced NO increase in wheat leaves through enzymatic and non-enzymatic pathway, and study the effects of exogenous SNP and NO scavenger (cPTIO) on antioxidant system, carbon assimilation and grain quality of winter wheat. The project will fill the gap in the study of NO on wheat resistance to ozone stress, and provide theoretical basis for exploring ways of mitigating ozone stress to crops.

近地面臭氧是对植物具有毒性的二次空气污染物。随着我国工业化和城市化的快速发展，臭氧浓度不断升高。国内外针对臭氧对作物的危害已经开展了大量的研究，但如何缓解臭氧危害的研究很少。冬小麦(Triticum aestivum)是我国重要的粮食作物，对臭氧污染非常敏感。申请人发现臭氧能够显著增加小麦叶片内源一氧化氮(NO)含量，并且外源喷施NO供体硝普钠(SNP)，能有效缓解臭氧对小麦的伤害。本项目将在此基础上，利用开顶式同化箱对2个冬小麦栽培品种进行臭氧熏蒸处理，从酶促、非酶促途径揭示臭氧引发小麦叶片NO含量升高的原因；并通过外源喷施SNP和NO清除剂(cPTIO)，研究不同水平NO对小麦抗氧化系统、碳同化及籽粒品质的影响。本研究将填补NO在小麦抵抗臭氧胁迫研究中的空白，并为探索缓解臭氧对作物造成危害的方法提供科学依据。

快速的工业化进程一直在增加臭氧前体物质的释放。目前，近地面臭氧浓度在持续升高，根据预测在未来的几十年臭氧浓度会一直保持不断升高的趋势。很多臭氧敏感型农作物的生产受到严重威胁，大量研究探索了臭氧对这些作物的伤害机制，例如冬小麦。然而，关于如何减缓臭氧对农作物的负面影响鲜有报道。一氧化氮，作为生物活性气体，可以调节多种生理过程，并在响应生物和非生物胁迫的过程中起到重要作用。在本项目研究中，在臭氧浓度升高环境中，小麦叶片内源一氧化氮含量增加。为了研究一氧化氮的功能，将其前体物质-硝普钠喷洒在小麦叶片上。结果发现，外源喷施硝普钠的小麦叶片活性氧含量显著降低，电导降低。因此，外源喷施硝普钠减少了小麦净光合速率的降低程度，籽粒产量损失也得到了显著的降低。这些结果对于理解一氧化氮在作物响应臭氧胁迫中的重要作用有很大帮助，还提供了一种缓解臭氧胁迫对作物生产造成负面影响的方法，这些对于保证粮食安全具有重要意义。