Zhang Hanghang, Yang Dong, Wang Peiqiang, Zhang Xinfu, Ding Zhaotang, Zhao Lei
College of Horticulture, Qingdao Agricultural University, Qingdao, China.
Front Genet. 2022 Feb 22;12:809608. doi: 10.3389/fgene.2021.809608. eCollection 2021.
Brassinosteroid (BR), a kind of polyhydroxylated steroid hormone, plays an important role in physiological and biochemical processes in plants. Studies were mainly focused on BR signaling and its exogenous spraying to help enhance crop yields. Few research studies are centered on the accumulation pattern of BR and its mechanism. Yet, it is crucial to unlock the mystery of the function of BR and its cross action with other hormones. Tea ( (L.) O. Kuntze) is one of the important economic crops in some countries, and new shoots are the raw materials for the preparation of various tea products. Different concentrations of exogenous BR were reported to have different effects on growth and development. New shoots of tea plants can thus be considered a valuable research object to study the accumulation pattern of BR. In this study, the quantity of five BR components (brassinolide, 28-norbrassinolide, 28-homobrassinolide, castasterone, and 28-norcastasterone) in different tissues of tea plants, including buds (Bud), different maturity of leaves (L1, L2), and stems (S1, S2) were determined by UPLC-MS/MS. A total of 15 cDNA libraries of the same tissue with three repetitions for each were constructed and sequenced. The BR-accumulation pattern and gene expression pattern were combined together for weighted gene co-expression network analysis (WGCNA). BR-accumulation-relative genes were then screened using two methods, based on the K.in value and BR biosynthetic pathway (ko00905), respectively. The result showed that photosynthesis-related genes and CYP450 family genes were actively involved and might play important roles in BR accumulation and/or its accumulation pattern. First and foremost, feedback inhibition was more likely to dominate the accumulation pattern of BR in the new shoots of tea plants. Moreover, three conserved miRNAs with their target transcriptional factors and target mRNAs had been figured out from negative correlation modules that might be strongly linked to the BR-accumulation pattern. Our study provided an experimental basis for the role of BR in tea plants. The excavation of genes related to the accumulation pattern of BR provided the possibility of cross-action studies on the regulation of BR biosynthesis and the study between BR and other hormones.
油菜素甾醇（BR）是一种多羟基甾体激素，在植物的生理生化过程中发挥着重要作用。研究主要集中在BR信号传导及其外源喷施以帮助提高作物产量。很少有研究关注BR的积累模式及其机制。然而，解开BR功能及其与其他激素相互作用之谜至关重要。茶（(L.) O. Kuntze）是一些国家重要的经济作物之一，新梢是制备各种茶产品的原料。据报道，不同浓度的外源BR对茶树的生长发育有不同影响。因此，茶树新梢可被视为研究BR积累模式的有价值研究对象。在本研究中，采用超高效液相色谱-串联质谱法（UPLC-MS/MS）测定了茶树不同组织中五种BR成分（油菜素内酯、28-去甲油菜素内酯、28-高油菜素内酯、castasterone和28-去甲castasterone）的含量，这些组织包括芽（Bud）、不同成熟度的叶片（L1、L2）和茎（S1、S2）。共构建了15个相同组织的cDNA文库，每个文库重复3次并进行测序。将BR积累模式和基因表达模式结合起来进行加权基因共表达网络分析（WGCNA）。然后分别基于K.in值和BR生物合成途径（ko00905），用两种方法筛选出与BR积累相关的基因。结果表明，光合作用相关基因和CYP450家族基因积极参与其中，可能在BR积累和/或其积累模式中发挥重要作用。首先，反馈抑制更有可能主导茶树新梢中BR的积累模式。此外，从负相关模块中找出了三个保守的miRNA及其靶转录因子和靶mRNA，它们可能与BR积累模式密切相关。我们的研究为BR在茶树中的作用提供了实验依据。挖掘与BR积累模式相关的基因，为BR生物合成调控的交叉作用研究以及BR与其他激素之间的研究提供了可能。
