Jiang Haiyang

Genome-wide analysis of NBS-encoding disease resistance genes in maize inbred line B73.

Nucleotide-binding site(NBS) disease resistance gene is a largest category in plant disease resistance genes,which is a focus in recent studies on molecular breeding of plant disease resistance.Using maize(Zea mays L.) inbred line B73,the complete set of disease resistance candidate genes that encode NBS was identified in the genome.The putative NBS genes were characterized with respect to structural diversity,phylogenetic relationships and so on.One hundred and sixty-five NBS-coding sequences were identified into two types:nonregular(12) and regular NBS genes(153).The amount of NBS genesis much smaller in maize than in japonica rice(Oryza sativa L.).The 153 regular NBS genes were categorized into eight classes,including CC-NBS-LRR,CC-NBS,NBS,NBS-NBS,NBS-LRR,NBS-NBS-LRR,NBS-X,and X-NBS,according to N-terminal motif and leucine-rich repeat(LRR) domains motif.The 165 NBS genes showed two remarkable branches in the phylogenetic tree,differing from the radiation structure in japonica rice.Gene duplication event was observed based on gene family analysis of the NBS disease-resistance genes in maize;however,the ratio of gene duplication was smaller than that in rice.This might be one of the reasons for less NBS disease-resistance genes in maize than in rice.