Systematic analysis of leucine-rich repeat disease resistance genes in maize

Leucine-rich repeat disease resistance (LRRDR) genes are important for defending plants from a range of pathogens. However, little information has been reported on the systematic analysis of LRRDR genes in maize. In this study, 235 LRRDR genes were identified in the complete genome sequence of maize (Zea mays cv. B73), classified as six different structural types, and then characterized based on conserved protein motifs, chromosomal locations and gene duplications. Subsequent phylogenetic comparisons indicated that similar to 20 pairs of maize LRRDR proteins possessed high similarities to LRRDR proteins with known functions. Analyses of the physical locations and duplications of LRRDR genes indicated that gene duplication events involving LRRDR genes were high in maize and 84% occurred between chromosomes, which may ensure the functional performance and enhancement of maize LRRDR genes. Meanwhile, the functions and expression patterns of the LRRDR genes were associated with their conserved protein secondary structures, suggesting that different conserved domains might distinguish their biological functions. Transcripts of 13 genes were regulated by two or more fungal pathogens, respectively, indicating that one LRRDR gene might mediate resistance to multiple fungal pathogens, suggesting that the signal networks of the maize-fungal pathogen interactions were partially crossed. Additionally, we screened five candidate LRRDR genes for ear rot resistance. The results reported in this study contribute to an improved understanding of the LRRDR gene family in maize.