Analysis of immune response-related LRR-RLKs differential genes in the rice blast resistance near-isogenic lines of <italic>Japonica</italic> Variety Yunyin

Abstract

Rice ( Oryza sativa L.) is a staple food in the world as well as an important monocotyledonous model plant for molecular biology, which has a long history of cultivation and domestication. However, many diseases will break out during rice production. For example, the rice blast is the most destructive disease, which can cause the heavy loss or even total crop failure. Therefore, there are constant demands to cultivate durably blast-resistant varieties and identify more broad-spectrum blast resistance genes. Besides, it’s also very significant for agricultural production to elucidate the process and mechanism of immune response during the rice blast infection. The whole-genome sequencing of the resistant and susceptible near-isogenic lines derived from the broad-spectrum blast resistance Japonica Variety Yunyin and the universally blast-susceptible variety Lijiangxintuanheigu (LTH) was completed. Eight differential genes were screened from the Go terms that were associated with the immune response based on the whole-genome sequence data. We analyzed their gene structure, evolution and sequence variability between the resistant and susceptible near-isogenic lines. The results indicated that the homology of these protein sequences was between 55% and 80%, and the conserved protein domain analysis showed that most of them contained different numbers and types of leucine-rich repeat domains, a transmembrane domain and a C-terminal kinase domain, which were typical leucine-rich repeat receptor-like protein kinases. Moreover, they are all located within a cluster of chromosome 11 and were homologous to the bacterial blight resistance gene Xa21 . The leucine-rich repeat receptor-like protein kinases (LRR-RLKs) genes are a large conserved superfamily during the plant evolution. In Arabidopsis , there are 14 subfamilies and more than 200 members of LRR-RLKs were identified, whereas the rice genome contained more than 900 LRR-RLKs genes. The perception and recognition of pathogen infection are mainly mediated by the plant cells surface pattern-recognition receptors (PRRs) and intracellular nucleotide-binding leucine-rich repeat (NLR) immune receptors. PRRs contain many receptor kinases including the leucine-rich repeat receptor-like protein kinases, which play an important role in the signal transduction during the plant development, immune response and sense of the environmental changes. In order to further explore the potential function of these genes during the rice blast disease response, the rice seedlings were inoculated with Magnaporthe oryzae by spray and punch methods and then the expression pattern of these genes during the fungal infection were analyzed by qRT-PCR. The results showed that some genes response to the blast disease. Thus, we speculated that some of them might be involved in the rice blast disease response. This study laid a foundation for further studying genes related to the rice blast disease response.