Data_Sheet_2_Beta-Amylase and Phosphatidic Acid Involved in Recalcitrant Seed Germination of Chinese Chestnut.XLS

Chinese chestnut (Castanea mollissima), a species with recalcitrant seeds, is an important source of nuts and forest ecosystem services. The germination rate of recalcitrant seeds is low in natural habitats and decreases under conditions of desiccation and low temperature. The germination rate of cultivated Chinese chestnut seeds is significantly higher than that of wild seeds. To explore the reasons for the higher germination rate of cultivated seeds in Chinese chestnut, 113,524 structural variants (SVs) between the wild and cultivated Chinese chestnut genomes were detected through genome comparison. Genotyping these SVs in 60 Chinese chestnut accessions identified allele frequency changes during Chinese chestnut domestication, and some SVs are overlapping genes for controlling seed germination. Transcriptome analysis revealed downregulation of the abscisic acid synthesis genes and upregulation of the beta-amylase synthesis genes in strongly selected genes of cultivated seeds. On the other hand, hormone and enzyme activity assays indicated a decrease in endogenous ABA level and an increase in beta-amylase activity in cultivated seeds. These results shed light on the higher germination rate of cultivated seeds. Moreover, phosphatidic acid synthesis genes are highly expressed in seed germination stages of wild Chinese chestnut and may play a role in recalcitrant seed germination. These findings provide new insight into the regulation of wild seed germination and promote natural regeneration and succession in forest ecosystems.

中国栗（Castanea mollissima），一种具有抗逆性种子的树种，是坚果和森林生态系统服务的重要来源。在自然生境中，抗逆性种子的发芽率较低，且在脱水及低温条件下进一步降低。相较于野生种子，栽培中国栗种子的发芽率显著提高。为探究栽培中国栗种子发芽率提高的原因，通过基因组比对检测到野生与栽培中国栗基因组间113,524个结构变异（SVs）。对60个中国栗种质资源中的这些SVs进行基因分型，揭示了在栗树驯化过程中的等位基因频率变化，并发现某些SVs与控制种子发芽的基因重叠。转录组分析显示，在栽培种子的强选择基因中，脱落酸合成基因的表达下调，而β-淀粉酶合成基因的表达上调。另一方面，激素和酶活性分析表明，在栽培种子中，内源脱落酸（ABA）水平降低，β-淀粉酶活性升高。这些结果为栽培种子发芽率提高提供了新的见解。此外，磷脂酸合成基因在野生中国栗种子发芽阶段高度表达，可能在抗逆性种子发芽中发挥作用。这些发现为野生种子发芽的调控提供了新的洞见，并促进了森林生态系统的自然更新和演替。