Jia Zhichao, Zhao Beibei, Liu Sian, Lu Zhaogeng, Chang Bang, Jiang Huiru, Cui Hui, He Qingsong, Li Weixing, Jin Biao, Wang Li
College of Horticulture and Plant Protection, Yangzhou University, Yangzhou 225009, China.
Tree Physiol. 2021 Apr 8;41(4):571-588. doi: 10.1093/treephys/tpaa023.
Seed dormancy is crucial for plant survival and prevents seed germination out of season. However, little is known about the regulatory mechanism of morphophysiological seed dormancy. Ginkgo biloba L. is one of the most ancient gymnosperms, and the completion of seed germination in this species requires cold and moist stratification. Here, we observed that at the mature seed stage, the embryo was not fully developed in G. biloba seeds. During dormancy stages, the length and weight of the embryo significantly increased, and nutrients accumulated in cotyledons. We further found that abscisic acid (ABA), gibberellic acid (GA), cytokinin and ethylene were integrated in the seed dormancy induction, maintenance and release processes, and GA biosynthesis and signaling transduction specifically act on dormancy release. Combining mRNA and miRNA analyses, we demonstrated that miRNA156 is involved in the regulation of morphophysiological dormancy. Our analyses revealed that G. biloba seed dormancy belongs to the ancestral morphophysiological dormancy type, which is not only regulated by the balance of ABA/GA, but also by other hormones associated with embryo morphological development, as well as genes related to embryo differentiation and development. These findings helped with elucidating the comprehensive regulatory network of morphophysiological dormancy in tree seeds.
种子休眠对于植物生存至关重要，并能防止种子在非季节萌发。然而，关于形态生理种子休眠的调控机制我们知之甚少。银杏是最古老的裸子植物之一，该物种种子萌发的完成需要冷湿层积处理。在此，我们观察到在成熟种子阶段，银杏种子的胚并未完全发育。在休眠阶段，胚的长度和重量显著增加，且子叶中积累了营养物质。我们进一步发现脱落酸（ABA）、赤霉素（GA）、细胞分裂素和乙烯参与了种子休眠的诱导、维持和解除过程，且GA生物合成和信号转导特异性作用于休眠解除。结合mRNA和miRNA分析，我们证明miRNA156参与了形态生理休眠的调控。我们的分析表明，银杏种子休眠属于原始的形态生理休眠类型，其不仅受ABA/GA平衡调控，还受与胚形态发育相关的其他激素以及与胚分化和发育相关基因的调控。这些发现有助于阐明树木种子形态生理休眠的综合调控网络。
