AUTHOR=Qian Lan-Hua , Wu Jia-Yi , Wang Yue , Zou Xin , Zhou Guang-Can , Sun Xiao-Qin 

TITLE=Genome-Wide Analysis of NBS-LRR Genes From an Early-Diverging Angiosperm Euryale ferox

JOURNAL=Frontiers in Genetics

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/genetics/articles/10.3389/fgene.2022.880071

DOI=10.3389/fgene.2022.880071

ISSN=1664-8021

ABSTRACT=<p><italic>NBS-LRR</italic> genes are the largest gene family in plants conferring resistance to pathogens. At present, studies on the evolution of <italic>NBS-LRR</italic> genes in angiosperms mainly focused on monocots and eudicots, while studies on <italic>NBS-LRR</italic> genes in the basal angiosperms are limited. <italic>Euryale ferox</italic> represents an early-diverging angiosperm order, Nymphaeales, and confronts various pathogens during its lifetime, which can cause serious economic losses in terms of yield and quality. In this study, we performed a genome-wide identification and analysis of <italic>NBS-LRR</italic> genes in <italic>E. ferox</italic>. All 131 identified <italic>NBS-LRR</italic> genes could be divided into three subclasses according to different domain combinations, including 18 <italic>RNLs</italic>, 40 <italic>CNLs</italic>, and 73 <italic>TNLs</italic>. The <italic>E. ferox NBS-LRR</italic> genes are unevenly distributed on 29 chromosomes; 87 genes are clustered at 18 multigene loci, and 44 genes are singletons. Gene duplication analysis revealed that segmental duplications acted as a major mechanism for <italic>NBS-LRR</italic> gene expansions but not for <italic>RNL</italic> genes, because 18 <italic>RNL</italic> genes were scattered over 11 chromosomes without synteny loci, indicating that the expansion of <italic>RNL</italic> genes could have been caused by ectopic duplications. Ancestral gene reconciliation based on phylogenetic analysis revealed that there were at least 122 ancestral <italic>NBS-LRR</italic> lineages in the common ancestor of the three Nymphaeaceae species, suggesting that <italic>NBS-LRR</italic> genes expanded slightly during speciation in <italic>E. ferox</italic>. Transcriptome analysis showed that the majority of <italic>NBS-LRR</italic> genes were at a low level of expression without pathogen stimulation. Overall, this study characterized the profile of <italic>NBS-LRR</italic> genes in <italic>E. ferox</italic> and should serve as a valuable resource for disease resistance breeding in <italic>E. ferox</italic>.</p>