Genome-wide identification and functional exploration of the legume lectin genes in Brassica napus and their roles in Sclerotinia disease resistance

Rong Zuo; Meili Xie; Feng Gao; Jie Liu; Minqiang Tang; Xiaohui Cheng; Yueying Liu; Zetao Bai; Shengyi Liu

doi:10.3389/fpls.2022.963263

Genome-wide identification and functional exploration of the legume lectin genes in Brassica napus and their roles in Sclerotinia disease resistance

Front Plant Sci. 2022 Jul 22:13:963263. doi: 10.3389/fpls.2022.963263. eCollection 2022.

Authors

Rong Zuo¹, Meili Xie¹, Feng Gao¹, Jie Liu¹, Minqiang Tang², Xiaohui Cheng¹, Yueying Liu¹, Zetao Bai¹, Shengyi Liu¹

Affiliations

¹ The Key Laboratory of Biology and Genetic Improvement of Oil Crops, The Ministry of Agriculture and Rural Affairs of PRC, Oil Crops Research Institute, Chinese Academy of Agricultural Sciences, Wuhan, China.
² Hainan University, Haikou, China.

Abstract

As one of the largest classes of lectins, legume lectins have a variety of desirable features such as antibacterial and insecticidal activities as well as anti-abiotic stress ability. The Sclerotinia disease (SD) caused by the soil-borne fungus Sclerotinia sclerotiorum is a devastating disease affecting most oil crops such as Brassica napus. Here, we identified 130 legume lectin (LegLu) genes in B. napus, which could be phylogenetically classified into seven clusters. The BnLegLu gene family has been significantly expanded since the whole-genome duplication (WGD) or segmental duplication. Gene structure and conserved motif analysis suggested that the BnLegLu genes were well conserved in each cluster. Moreover, relative to those genes only containing the legume lectin domain in cluster VI-VII, the genes in cluster I-V harbored a transmembrane domain and a kinase domain linked to the legume lectin domain in the C terminus. The expression of most BnLegLu genes was relatively low in various tissues. Thirty-five BnLegLu genes were responsive to abiotic stress, and 40 BnLegLu genes were strongly induced by S. sclerotiorum, with a most significant up-regulation of 715-fold, indicating their functional roles in SD resistance. Four BnLegLu genes were located in the candidate regions of genome-wide association analysis (GWAS) results which resulted from a worldwide rapeseed population consisting of 324 accessions associated with SD. Among them, the positive role of BnLegLus-16 in SD resistance was validated by transient expression in tobacco leaves. This study provides important information on BnLegLu genes, particularly about their roles in SD resistance, which may help targeted functional research and genetic improvement in the breeding of B. napus.

Keywords: Brassica napus; Sclerotinia sclerotiorum; genome-wide association study; legume lectin; phylogenetic analysis.