中国农业科学 ›› 2022, Vol. 55 ›› Issue (6): 1047-1063.doi: 10.3864/j.issn.0578-1752.2022.06.001

• 作物遗传育种·种质资源·分子遗传学 • 上一篇    下一篇

种子耐脱水性的生理及分子机制研究进展

宋松泉1,2(),刘军1(),唐翠芳3,程红焱2,王伟青2,张琪1,张文虎1,高家东1   

  1. 1广东省农业科学院农业生物基因研究中心/广东省农作物种质资源保存与利用重点实验室,广州 510640
    2中国科学院植物研究所,北京 100093
    3深圳前海国垦大地基金管理有限公司,广州 510630
  • 收稿日期:2021-08-12 接受日期:2021-10-08 出版日期:2022-03-16 发布日期:2022-03-25
  • 通讯作者: 宋松泉,刘军
  • 基金资助:
    国家科技支撑计划(2012BAC01B05);广东省农作物种质资源保存与利用重点实验室项目(2020B121201008);国家自然科学基金(31871716)

Research Progress on the Physiology and Its Molecular Mechanism of Seed Desiccation Tolerance

SONG SongQuan1,2(),LIU Jun1(),TANG CuiFang3,CHENG HongYan2,WANG WeiQing2,ZHANG Qi1,ZHANG WenHu1,GAO JiaDong1   

  1. 1Agro-Biological Gene Research Center, Guangdong Academy of Agricultural Sciences/Guangdong Provincial Key Lab for Crop Germplasm Resources Preservation and Utilization, Guangzhou 510640
    2Institute of Botany, Chinese Academy of Sciences, Beijing 100093
    3Shenzhen Qianhai Guoken Earth Fund Management Co., Ltd, Guangzhou 510630
  • Received:2021-08-12 Accepted:2021-10-08 Online:2022-03-16 Published:2022-03-25
  • Contact: SongQuan SONG,Jun LIU

摘要:

耐脱水性是指生物体或组织在丧失所有或几乎所有细胞水分的状态下而不产生不可逆损伤的存活能力。种子的耐脱水性是植物在长期进化过程中保证物种生存和繁衍的适应性机制,在植物种子(质)资源保存中起关键作用。种子的耐脱水性是一个复杂的性状,其分子机理至今尚不清楚。为此,本文综述了种子耐脱水性的生理及分子机制的研究进展。研究发现,正常性种子的耐脱水性是在发育过程中逐渐形成的,在生理成熟期达到峰值;顽拗性种子在整个发育过程中对脱水敏感,不具有成熟脱水的发育阶段。成熟的正常性种子在吸胀初期保持对重新脱水的耐性,随着萌发进程,种子的耐脱水性逐渐下降,最后完全丧失;在萌发初期,种子的耐脱水性可以重建,不同组织具有不同的耐脱水性。种子和胚的耐脱水性程度与其线粒体的呼吸活性下降呈负相关性,顽拗性种子的呼吸活性高于正常性种子。脱水过程中,耐脱水性胚(轴)的H2O2含量、超氧阴离子自由基(·O2-)的产生速率和硫代巴比妥酸活性产物的含量显著低于脱水敏感性胚(轴),而活性氧清除(包括酶促和非酶促)系统的活性明显高于脱水敏感性胚(轴)。种子成熟过程中,胚胎发育晚期丰富(LEA)蛋白、小分子量热休克蛋白和非还原性棉子糖家族寡聚糖的积累与耐脱水性的形成密切相关。B3转录因子的AFL亚家族(包括ABI3(ABA INSENSITIVE 3)、FUS3(FUSCA3)和LEC2(LEAFY COTYLEDON 2))通过正向调控贮藏物和保护性蛋白的积累增加种子(胚)的耐脱水性。在整个种子发育过程中,DNA甲基化水平显著增加,随后在种子萌发过程中逐渐降低;与发育早期阶段的胚和幼苗相比,成熟胚具有较高水平的基因组甲基化。在种子中,平行的ABA和DOG1(DELAY OF GERMINATION 1)信号转导途径激活棉子糖家族寡聚糖的合成、LEA基因和HSP基因的表达,从而调控耐脱水性的起始和向休眠转变。最后,本文提出了该领域需要进一步研究的科学问题,包括利用种子及其组织的不同耐脱水性重建其模式研究系统;种子的萌发能力、耐脱水性和休眠特性都是在发育过程中起始和完成的,它们之间的相互关系仍不清楚;种子中同时存在核心ABA信号途径和DOG1信号途径,这两条途径在ABI3或者ABI3下游汇合,在种子脱水过程中哪条途径优先响应?又是如何协调?本文将为全面理解种子耐脱水性的生理及其分子机制、提高农作物的胁迫抗性与产量、改善资源库的贮藏条件和长期保存植物种子(质)资源提供参考。

关键词: 抗氧化系统, 耐脱水性, 遗传调控, 种质资源的长期保存, 代谢活性, 保护性物质

Abstract:

Dehydration tolerance (DT) is defined as the ability of an organism or tissue to survive the removal of all, or almost all the cellular water without irreversible damage. DT of seeds is an adaptive mechanism to ensure the survival and reproduction of plant species in the long-term evolution process, and plays a key role in the conservation of plant seeds and germplasm resources. However, the DT of seeds is a complex trait, and its molecular mechanism is not now largely understood. Therefore, in the present paper, the research progresses on the physiological and molecular mechanisms of seed DT were reviewed. It was found that the DT of orthodox seeds was gradually formed during development, and reached the peak at physiological maturity. Recalcitrant seeds do not undergo the development stage of maturity dehydration, and are very sensitive to dehydration throughout development. Mature orthodox seeds maintained their resistance to re-dehydration at the initial stage of imbibition. With the time course of germination, the DT decreased gradually, and finally lost completely. The DT of seeds and embryos can be re-established during the early stage of germination, and of different tissues is different. The DT of seeds and embryos was inversely correlated with the decrease in mitochondrial respiratory activity. Respiratory activity of recalcitrant axis mitochondria was higher than that of orthodox embryo ones. During dehydration, the H2O2 content, the production rate of superoxide anion radical (·O2-) and the content of thiobarbituric acid reactive substance in desiccation-tolerant embryos (axes) were significantly lower than those of desiccation-sensitive embryos (axes), while the reactive oxygen species scavenging system in desiccation-tolerant embryos (axes), including enzymatic and non-enzymatic activities, was significantly higher than that in desiccation-sensitive embryos (axes). During the maturation of seeds, the accumulation of late embryogenesis abundant (LEA) proteins, small heat shock proteins and non-reducing oligosaccharides is closely related to the formation of DT. The AFL subfamily of B3 transcription factors (including ABI3 (ABA INSENSITIVE 3), FUS3 (FUSCA3) and LEC2 (LEAFY COTYLEDON 2)) increase the DT of seeds and embryos by positively regulating the accumulation of storage materials and protective proteins. The level of DNA methylation increased significantly throughout seed development and then decreased gradually during seed germination. Compared with embryos during the early stage of development and seedlings, mature embryos had a higher level of genomic methylation. In seeds, the parallel ABA and DOG1 (DELAY OF GERMINATION 1) signaling pathways activate synthesis of raffinose family oligosaccharides, and expression of LEA and HSP (heat shock protein) genes, thus regulating the onset of DT and transit to dormancy. Finally, the scientific issues that require to be further studied in this field are proposed, including the re-establishment of their model research system by using seeds and their tissues with different DT. Germinability, DT and dormancy characteristics of seeds are initiated and completed during development, and the relationship among them is still now unclear. There are both core ABA signaling pathway and DOG1 signaling pathway in seeds, and they converge at the ABI3 or downstream of ABI3. Which pathway will response preferentially and how these two pathways coordinate during dehydration of seeds? This paper will provide a reference for comprehensively understanding of the physiology and molecular mechanism of seed DT, increasing the stress resistance and yield of plant crops, improving the storage conditions of the resource bank and long-term preserving plant seed (germplasm) resources.

Key words: antioxidant system, desiccation tolerance, genetic regulation, long-term conservation of germplasm resource, metabolic activity, protective substance