Journal of Integrative Agriculture

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油菜素甾醇通过改善低氮胁迫下小麦小花的氧化还原状态缓解小花退化

  

  • 修回日期:2024-04-08

Brassinosteroids improve the redox state of wheat florets under low-nitrogen stress and alleviate degeneration

Zimeng Liang1, Juan Li1, Jingyi Feng1, Zhiyuan Li1, Vinay Nangia2, Fei Mo1, Yang Liu1#   

  1. 1 College of Agronomy, Northwest A&F University, Yangling 712100, China

    2 International Center for Agricultural Research in the Dry Areas, Rabat 999055, Morocco

  • Revised:2024-04-08
  • About author:#Correspondence Yang Liu, E-mail: liuyang0328@126.com, yangl@nwafu.edu.cn

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摘要： 减少施氮量可以缓解环境退化和资源浪费等问题。然而，减少施氮量也会加剧小麦小花退化的问题，导致产量下降。因此，研究低氮胁迫下小麦小花退化机制，明确缓解措施，有利于实现小麦高产和可持续发展。为了探讨低氮胁迫影响小麦小花退化的生理机制以及外源油菜素甾醇是否可以缓解该胁迫，本研究设置了氮肥梯度试验（N0，不施氮；N1，120 kg ha-1纯氮；N2，240 kg ha-1纯氮）和外源叶面喷施试验（N0CK，不施氮+外源喷施纯水；N0BR，不施氮+外源喷施 24-表油菜素内酯（一种有活性的油菜素甾醇类激素）；和N1，120kg ha-1纯氮+外源喷施纯水）。结果表明，低氮胁迫诱导小麦产生了大量活性氧。尽管小麦穗通过合成黄酮类化合物来对抗氧化应激，但它们的能量代谢（糖酵解和三羧酸循环）和抗坏血酸谷胱甘肽循环被抑制，使穗内的活性氧水平仍处于较高水平，从而诱导细胞死亡，加剧小花退化。此外，油菜素甾醇在低氮胁迫下对小麦小花退化具有调控作用。外源叶面喷施24-表油菜素内酯促进了穗的能量代谢和抗坏血酸-谷胱甘肽循环，增加了能量电荷，有效消除了部分由低氮胁迫诱导生产的活性氧，从而缓解了由低氮应激引起的小花退化。总之，低氮胁迫破坏了小麦穗的氧化还原稳态，导致小花退化。油菜素甾醇通过改善低氮下小麦穗的氧化还原状态缓解了小花退化。本研究为解决高产与可持续发展之间的矛盾提供了理论支持，有利于小麦生产中的“减氮高效”。

Abstract: Reducing nitrogen application rates can mitigate issues such as environmental degradation and resource wastage.  However, it can also exacerbate problems such as wheat floret degeneration, leading to reduced yields.  Therefore, investigating wheat floret degeneration mechanisms under low nitrogen stress and identifying mitigation measures are conducive to achieving high yields and sustainable development.  To investigate the physiological mechanism of low nitrogen stress affecting wheat floret degradation and whether exogenous brassinosteroids can alleviate this stress, three nitrogen application rates (N0, no nitrogen application; N1, 120 kg ha-1 pure nitrogen; and N2, 240 kg ha-1 pure nitrogen) and exogenous spraying experiments (N0CK, no nitrogen with water spraying; N0BR, no nitrogen with 24-epibrassinolide (an active brassinosteroids) spraying; and N1, 120 kg ha-1 pure nitrogen with water spraying) were designed.  The results indicated that low nitrogen stress induced a large amount of reactive oxygen species generation.  Although wheat spikes synthesized flavonoids to combat oxidative stress, their energy metabolism (glycolysis and tricarboxylic acid cycle) and ascorbate-glutathione cycle were inhibited, keeping reactive oxygen levels elevated within the spike, inducing cell death and exacerbating floret degeneration.  Furthermore, brassinosteroids played a role in regulating wheat floret degeneration under low-nitrogen stress.  Exogenous foliar spraying of 24-epibrassinolide promoted energy metabolism and the ascorbate-glutathione cycle within the spike, enhancing energy charge and effectively mitigating a portion of reactive oxygen induced by low nitrogen stress, thereby alleviating floret degeneration caused by low nitrogen stress.  In summary, low-nitrogen stress disrupts the redox homeostasis of wheat spikes, leading to floret degeneration.  Brassinosteroids alleviate floret degeneration by improving the redox state of wheat spikes.  This research provides theoretical support for balancing the contradiction between high yields and sustainable development and is beneficial for the application of low nitrogen in production.

Key words: brassinosteroids ,  , fertile florets ,  , nitrogen application rate ,  , reactive oxygen ,  , wheat