Luo Yongjian, Zhang Yixin, Le Jingyu, Li Qing, Mou Jiaolin, Deng Shiming, Li Jitao, Wang Ru, Deng Zhijun, Liu Jun
Hubei Key Laboratory of Biologic Resources Protection and Utilization, Hubei Minzu University, Enshi 445000, China.
Guangdong Key Laboratory for Crop Germplasm Resources Preservation and Utilization, Agro-Biological Gene Research Center, Guangdong Academy of Agricultural Sciences, Guangzhou 510640, China.
Antioxidants (Basel). 2023 Jun 27;12(7):1353. doi: 10.3390/antiox12071353.
Hu and W. C. Cheng, as the only surviving relict species of the Taxodiaceae genus, is a critically endangered and protected species in China. There is a risk of extinction due to the low vigor of seeds, and the physiological mechanism of seed aging in is not yet clear. In order to investigate the physiological and molecular mechanisms underlying the aging process of seeds, we analyzed the antioxidant system and transcriptome at 0, 2, 4, 6, and 8 days after artificial accelerated aging treatment at 40 °C and 100% relative humidity. It was found that the germination percentage of fresh dried seeds was 54 ± 5.29%, and significantly declined to 9.33 ± 1.88% after 6 days of aging, and then gradually decreased until the seed died on day 8. Superoxide dismutase (SOD) activity, ascorbic acid (AsA), glutathione (GSH) content and superoxide anion (O) content and production rate significantly decreased, while malondialdehyde (MDA) and hydrogen peroxide (HO) content and glutathione peroxidase (GPX) and catalase (CAT) activity gradually increased during the aging process. A total of 42,189 unigenes were identified in the whole transcriptome, and 40,446 (95.86%) unigenes were annotated in at least one protein database. A total of 15,376 differentially expressed genes (DEGs) were obtained; KEGG enrichment analysis results revealed that seed aging may be mainly involved in the protein-processing pathways in endoplasmic reticulum, oxidative phosphorylation, and ascorbate and aldarate metabolism. Weighted gene co-expression network analysis (WGCNA) revealed that the dark magenta, orange, and medium purple modules were highly correlated with physiological indicators such as SOD, CAT, and GSH and further identified 40 hub genes such as , , , and as playing important roles in the antioxidant network of seeds. These findings provide a broader perspective for studying the regulatory mechanism of seed aging and a large number of potential target genes for the breeding of other endangered gymnosperms.
水杉是杉科仅存的孑遗物种，在中国是极度濒危的保护植物。由于种子活力低，存在灭绝风险，其种子衰老的生理机制尚不清楚。为了探究水杉种子衰老过程的生理和分子机制，我们在40℃、相对湿度100%的人工加速老化处理后0、2、4、6和8天分析了抗氧化系统和转录组。结果发现，新鲜干燥的水杉种子发芽率为54±5.29%，老化6天后显著降至9.33±1.88%，然后逐渐下降，直至第8天种子死亡。在老化过程中，超氧化物歧化酶（SOD）活性、抗坏血酸（AsA）、谷胱甘肽（GSH）含量以及超氧阴离子（O）含量和产生速率显著下降，而丙二醛（MDA）和过氧化氢（H₂O₂）含量以及谷胱甘肽过氧化物酶（GPX）和过氧化氢酶（CAT）活性逐渐增加。在整个转录组中总共鉴定出42189个单基因，其中40446个（95.86%）单基因在至少一个蛋白质数据库中得到注释。共获得15376个差异表达基因（DEG）；KEGG富集分析结果表明，种子衰老可能主要涉及内质网中的蛋白质加工途径、氧化磷酸化以及抗坏血酸和醛糖代谢。加权基因共表达网络分析（WGCNA）表明，暗紫红色、橙色和中紫色模块与SOD、CAT和GSH等生理指标高度相关，并进一步鉴定出如[此处原文缺失具体基因名称]等40个枢纽基因在水杉种子抗氧化网络中起重要作用。这些发现为研究种子衰老调控机制提供了更广阔的视角，并为其他濒危裸子植物的育种提供了大量潜在靶基因。
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