Ren Zhaobin, Wang Xing, Tao Qun, Guo Qing, Zhou Yuyi, Yi Fei, Huang Guanmin, Li Yanxia, Zhang Mingcai, Li Zhaohu, Duan Liusheng
State Key Laboratory of Plant Physiology and Biochemistry, Engineering Research Center of Plant Growth Regulator, Ministry of Education &College of Agronomy and Biotechnology, China Agricultural University, No.2 Yuanmingyuan West Road, Haidian, Beijing, 100193, China.
College of Plant Science and Technology, Beijing University of Agriculture, No.7 Beinong Road, Changping, Beijing, 102206, China.
BMC Plant Biol. 2021 Apr 27;21(1):202. doi: 10.1186/s12870-021-02962-2.
Lodging is one of the important factors causing maize yield. Plant height is an important factor in determining plant architecture in maize (Zea mays L.), which is closely related to lodging resistance under high planting density. Coronatine (COR), which is a phytotoxin and produced by the pathogen Pseudomonas syringae, is a functional and structural analogue of jasmonic acid (JA).
In this study, we found COR, as a new plant growth regulator, could effectively reduce plant height and ear height of both hybrids (ZD958 and XY335) and inbred (B73) maize by inhibiting internode growth during elongation, thus improve maize lodging resistance. To study gene expression changes in internode after COR treatment, we collected spatio-temporal transcriptome of inbred B73 internode under normal condition and COR treatment, including the three different regions of internode (fixed, meristem and elongation regions) at three different developmental stages. The gene expression levels of the three regions at normal condition were described and then compared with that upon COR treatment. In total, 8605 COR-responsive genes (COR-RGs) were found, consist of 802 genes specifically expressed in internode. For these COR-RGs, 614, 870, 2123 of which showed expression changes in only fixed, meristem and elongation region, respectively. Both the number and function were significantly changed for COR-RGs identified in different regions, indicating genes with different functions were regulated at the three regions. Besides, we found more than 80% genes of gibberellin and jasmonic acid were changed under COR treatment.
These data provide a gene expression profiling in different regions of internode development and molecular mechanism of COR affecting internode elongation. A putative schematic of the internode response to COR treatment is proposed which shows the basic process of COR affecting internode elongation. This research provides a useful resource for studying maize internode development and improves our understanding of the COR regulation mechanism based on plant height.
倒伏是影响玉米产量的重要因素之一。株高是决定玉米（Zea mays L.）植株形态的重要因素，在高密度种植条件下与抗倒伏能力密切相关。冠菌素（COR）是一种由丁香假单胞菌病原体产生的植物毒素，是茉莉酸（JA）的功能和结构类似物。
在本研究中，我们发现COR作为一种新型植物生长调节剂，可通过抑制伸长过程中节间生长，有效降低杂交种（郑单958和先玉335）和自交系（B73）玉米的株高和穗位高，从而提高玉米的抗倒伏能力。为了研究COR处理后节间的基因表达变化，我们收集了自交系B73节间在正常条件和COR处理下的时空转录组，包括节间三个不同发育阶段的三个不同区域（固定区、分生区和伸长区）。描述了正常条件下三个区域的基因表达水平，然后与COR处理后的进行比较。总共发现了8605个COR响应基因（COR-RGs），其中802个基因在节间特异性表达。对于这些COR-RGs，其中614、870、2123个分别仅在固定区、分生区和伸长区表现出表达变化。不同区域鉴定出的COR-RGs数量和功能均发生了显著变化，表明不同功能的基因在这三个区域受到调控。此外，我们发现超过80%的赤霉素和茉莉酸基因在COR处理下发生了变化。
这些数据提供了节间发育不同区域的基因表达谱以及COR影响节间伸长的分子机制。提出了节间对COR处理响应的推测示意图，展示了COR影响节间伸长的基本过程。本研究为研究玉米节间发育提供了有用的资源，并增进了我们对基于株高的COR调控机制的理解。
