Li Kaiyuan, Lin Jiayi, Fan Rong, Chen Sibo, Ma Zhilin, Ji Wenli
College of Landscape Architecture and Art, Northwest A&F University, Yangling, China.
Institute of Wetland and Grassland Conservation, Shaanxi Academy of Forestry, Xian, China.
Front Plant Sci. 2024 Dec 10;15:1495784. doi: 10.3389/fpls.2024.1495784. eCollection 2024.
Mast. is a rare and threatened species of evergreen coniferous tree in China, commonly facing issues such as damaged seeds, abnormal seed growth, and empty seed shells. These abnormalities vary by location; unfortunately, the reasons behind these inconsistencies are completely unknown. This study compared seeds from two 150-year-old trees located in Taibai (Shaanxi province, TB150) and Zhouqu (Gansu province, ZQ150). The results showed significant differences in 43 metabolites and hormone levels, with higher levels of indole-3-acetic acid (IAA), methyl jasmonate (MeJA), and brassinosteroid (BR) in ZQ150, which were associated with more viable seeds. In contrast, TB150 exhibited more damaged seeds and empty seed shells due to higher abscisic acid (ABA) levels. Moreover, to further investigate these inconsistencies, we performed transcriptomic assembly and functional annotation of unigenes using high-throughput sequencing. A total of 2,355 differentially expressed unigenes were identified between TB150 and ZQ150, with 1,280 upregulated and 1,075 downregulated. Hormone signaling and sugar metabolism-related unigenes were further examined for their role in seed development. ZQ150 increased the number of normal seeds by enhancing endogenous IAA levels and upregulating auxin signaling and sugar metabolism-related genes. Conversely, TB150 showed more empty seed shells, correlated with elevated ABA levels and the activation of ABA signaling genes. We hypothesize that enhanced IAA levels and the upregulation of sugar metabolism and auxin signaling genes promote normal seed development.
巴山冷杉是中国一种珍稀且受威胁的常绿针叶树种，通常面临种子受损、种子生长异常和种壳空瘪等问题。这些异常情况因地点而异；不幸的是，这些不一致现象背后的原因完全未知。本研究比较了位于太白（陕西省，TB150）和舟曲（甘肃省，ZQ150）的两棵150年树龄的树木的种子。结果显示，43种代谢物和激素水平存在显著差异，ZQ150中吲哚 - 3 - 乙酸（IAA）、茉莉酸甲酯（MeJA）和油菜素内酯（BR）水平较高，这与更多有活力的种子相关。相比之下，TB150由于脱落酸（ABA）水平较高，种子受损和种壳空瘪的情况更多。此外，为了进一步研究这些不一致现象，我们使用高通量测序对单基因进行了转录组组装和功能注释。在TB150和ZQ150之间共鉴定出2355个差异表达的单基因，其中1280个上调，1075个下调。进一步研究了激素信号和糖代谢相关单基因在种子发育中的作用。ZQ150通过提高内源IAA水平以及上调生长素信号和糖代谢相关基因，增加了正常种子的数量。相反，TB150种壳空瘪的情况更多，这与ABA水平升高和ABA信号基因的激活有关。我们推测，IAA水平的提高以及糖代谢和生长素信号基因的上调促进了种子的正常发育。
