AUTHOR=Xing Jing , Zhao Ruijie , Zhang Qing , Huang Xinru , Yin Tingchao , Zhang Jing , Xu Bin 

TITLE=Genome-Wide Identification and Characterization of the LpSAPK Family Genes in Perennial Ryegrass Highlight LpSAPK9 as an Active Regulator of Drought Stress

JOURNAL=Frontiers in Plant Science

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2022.922564

DOI=10.3389/fpls.2022.922564

ISSN=1664-462X

ABSTRACT=<p><italic>SAPK/SnRK2</italic> family genes play crucial roles in plant growth, development, and abiotic stress responses. The objective of this study was to identify and characterize the <italic>LpSAPK</italic> genes in perennial ryegrass (<italic>Lolium perenne</italic> L.). The results showed that there are 10 <italic>LpSAPKs</italic> in perennial ryegrass that could be classified into three groups with similar genic (exon–intron) structures to their orthologous genes in Arabidopsis and other grass species. Ka/Ks analysis suggested that the <italic>LpSAPKs</italic> and their orthologs were under purifying selection to maintain their conserved function during evolution. Nine out of ten <italic>LpSAPKs</italic> were localized in the cytoplasm and nucleus with the exception of LpSAPK5 which was only observed in the cytoplasm. Most <italic>LpSAPKs</italic> were responsive to various abiotic stress and hormonal (ABA, cytokinin, and ethylene) treatments but were downregulated in leaves and upregulated in roots, suggesting that there were unknown <italic>cis</italic> elements in promoters of these genes or unidentified post-transcriptional mechanism responsible for the tissue-dependent stress-regulated expression of these <italic>LpSAPKs</italic>. Furthermore, <italic>LpSAPK9</italic> was identified as a candidate positive regulator in drought tolerance using a yeast ectopic expression system, and <italic>LpSAPK9</italic> showed contrasting expression changes in drought-sensitive and -tolerant ryegrass varieties, suggesting that expression levels of <italic>LpSAPK9</italic> were related to ryegrass drought tolerance. These results will facilitate further functional analysis of <italic>LpSAPKs</italic> for molecular breeding of ryegrass and other related grass species.</p>