Li Ping, Zheng Tangchun, Li Lulu, Liu Weichao, Qiu Like, Ahmad Sagheer, Wang Jia, Cheng Tangren, Zhang Qixiang
Beijing Key Laboratory of Ornamental Plants Germplasm Innovation and Molecular Breeding, National Engineering Research Center for Floriculture, Beijing Laboratory of Urban and Rural Ecological Environment, Engineering Research Center of Landscape Environment of Ministry of Education, Key Laboratory of Genetics and Breeding in Forest Trees and Ornamental Plants of Ministry of Education, School of Landscape Architecture, Beijing Forestry University, Beijing, China.
College of Landscape and Tourism, Hebei Agricultural University, Baoding, China.
J Exp Bot. 2023 Mar 28;74(6):2173-2187. doi: 10.1093/jxb/erad027.
Low temperature is one of the most important abiotic factors limiting the growth, development and geographical distribution of plants. Prunus mume is an attractive woody ornamental plant that blooms in early spring in Beijing. However, the molecular mechanisms underlying cold hardening to enhance freezing tolerance in Prunus genus remains elusive. This study examined the dynamic physiological responses induced by cold hardening, and identified freezing-tolerance genes by RNA-seq and ATAC-seq analyses. Cold hardening elevated the content of soluble substances and enhanced freezing resistance in P. mume. Transcriptome analysis indicated that the candidate differentially expressed genes (DEGs) were those enriched in Ca2+ signalling, mitogen-activated protein kinase (MAPK) cascade, abscisic acid signalling, and inducer of CBF expression 1 (ICE)-C-repeat binding factor (CBF) signalling pathways. The openness of gene chromatin positively correlated with the expression level of these genes. Thirteen motifs were identified in the open chromatin regions in the treatment group subjected to freezing after cold hardening. The chromatin opening of transcription start site at the proximal -177 region of cold-shock protein CS120-like (PmCSL) was markedly increased, while the expression level of PmCSL was significantly up-regulated. Overexpression of PmCSL in Arabidopsis significantly improved the freezing tolerance of transgenic plants. These findings provide new insights into the regulatory mechanism of freezing tolerance to improve breeding of cold-hardy P. mume plants.
低温是限制植物生长、发育和地理分布的最重要非生物因素之一。梅花是一种引人注目的木本观赏植物，在北京早春开花。然而，李属植物中增强抗冻性的低温驯化分子机制仍不清楚。本研究检测了低温驯化诱导的动态生理反应，并通过RNA测序和ATAC测序分析鉴定了抗冻基因。低温驯化提高了梅花中可溶性物质的含量并增强了其抗冻性。转录组分析表明，候选差异表达基因（DEG）富集于Ca2+信号传导、丝裂原活化蛋白激酶（MAPK）级联、脱落酸信号传导以及CBF表达诱导因子1（ICE）-C-重复结合因子（CBF）信号通路。基因染色质的开放性与这些基因的表达水平呈正相关。在低温驯化后经冷冻处理的实验组开放染色质区域中鉴定出13个基序。冷休克蛋白CS120-like（PmCSL）近端-177区域转录起始位点的染色质开放性明显增加，而PmCSL的表达水平显著上调。在拟南芥中过表达PmCSL显著提高了转基因植物的抗冻性。这些发现为抗冻性调控机制提供了新见解，以改善耐寒梅花植物的育种。
