Chen Yan, Ma Xiangwei, Xue Xiaodong, Liu Mengyu, Zhang Xueying, Xiao Xuechen, Lai Chunwang, Zhang Zihao, Lai Zhongxiong, Lin Yuling
Institute of Horticultural Biotechnology, Fujian Agriculture and Forestry University, Fuzhou, Fujian, 350002, China.
Institute of Horticultural Biotechnology, Fujian Agriculture and Forestry University, Fuzhou, Fujian, 350002, China.
Plant Physiol Biochem. 2023 Feb;195:362-374. doi: 10.1016/j.plaphy.2023.01.006. Epub 2023 Jan 14.
The early auxin responsive small auxin up-regulated RNA (SAUR) family is an important gene family in the auxin signal transduction pathway. This study focused on the regulatory mechanism of DlSAUR genes during early somatic embryogenesis (SE) and its response to hormone treatment and abiotic stress. Mining of the available Dimocarpus longan Lour. (D. longan) genome sequence yielded 68 putative SAUR genes. Transcript profiles based on RNA-seq data showed that most of the 24 detected DlSAUR genes were highly expressed in the globular embryos (GE) (10) and most of them responded to heat stress and 2,4-D treatment. The results of qRT-PCR showed that most of DlSAUR genes were up-regulated under auxin inhibitor N-1-naphthylphthalamic acid (NPA) and auxin indole-3-acetic acid (IAA) treatments. Moreover, NPA could promote longan SE. The assay for ATAC-seq data analysis showed that chromatin accessibility of 19 of the 24 DlSAUR genes were open during early SE, and most DlSAUR genes differentially expressed during early SE were not associated with H3K4me1 signal enrichment. The DlSAUR32 was selected for subcellular localization and RNA-seq analysis, which encode a cell nuclear-localized protein. Dual-luciferase assays and transient transformation showed that the transcription factors (TFs) DlWRKY75-1 and DlWRKY75-2 might bind to the DlSAUR32 promoters to inhibition gene transcription. Transient overexpression of DlWRKY75-1 and DlWRKY75-2 decreased IAA content in N. benthamiana leaves. Thus, the regulatory network composed of DlSAUR32 and its related TFs may regulate the early longan SE and be involved in the auxin response regulatory pathway of longan.
早期生长素响应的小生长素上调RNA（SAUR）家族是生长素信号转导途径中的一个重要基因家族。本研究聚焦于龙眼早期体细胞胚胎发生（SE）过程中DlSAUR基因的调控机制及其对激素处理和非生物胁迫的响应。对现有龙眼基因组序列进行挖掘，得到68个推定的SAUR基因。基于RNA测序数据的转录谱显示，检测到的24个DlSAUR基因中的大多数在球形胚（GE）中高表达（10个），且其中大多数对热胁迫和2,4-D处理有响应。qRT-PCR结果表明，大多数DlSAUR基因在生长素抑制剂N-1-萘基邻苯二甲酸（NPA）和生长素吲哚-3-乙酸（IAA）处理下上调。此外，NPA可促进龙眼体细胞胚胎发生。ATAC-seq数据分析结果显示，24个DlSAUR基因中的19个在早期体细胞胚胎发生过程中染色质可及性开放，且早期体细胞胚胎发生过程中差异表达的大多数DlSAUR基因与H3K4me1信号富集无关。选择DlSAUR32进行亚细胞定位和RNA测序分析，其编码一种细胞核定位蛋白。双荧光素酶测定和瞬时转化表明，转录因子DlWRKY75-1和DlWRKY75-2可能与DlSAUR32启动子结合以抑制基因转录。DlWRKY75-1和DlWRKY75-2的瞬时过表达降低了本氏烟草叶片中的IAA含量。因此，由DlSAUR32及其相关转录因子组成的调控网络可能调控龙眼早期体细胞胚胎发生，并参与龙眼的生长素响应调控途径。
