Poster
Shankar Gaire
Louisiana State University
Baton Rouge, Louisiana, United States
Bernard Budot
Louisiana State University
Baton Rouge, Louisiana, United States
Jacob Searight
LSU AgCenter
Baton Rouge, Louisiana, United States
Brijesh Angira
Louisiana State University Agricultural Center
Crowley, Louisiana, United States
Adam Famoso
Louisiana State University Agricultural Center
Crowley, Louisiana, United States
Jonathan K. Richards
Louisiana State University
Baton Rouge, Louisiana, United States
Cercospora janseana is a fungal pathogen of rice that causes narrow brown leaf spot. The CRSP2.1 locus provides high levels of resistance and distinct CRSP2.1 haplotypes confer resistance to different C. janseana pathotypes. However, the underlying resistance gene is unknown. To address this knowledge gap, we took a fine mapping and comparative genomics approach to identify and validate CRSP2.1 candidate genes. Five recombinant inbred lines derived from a LaGrue (resistant) x Cypress (susceptible) cross were found to be heterozygous across the CRSP2.1 region and were selfed to produce heterozygous inbred families (HIFs). Over 10,000 F2:3 HIF individuals were genotyped with eight SNP markers which identified 26 recombinants. Critical recombinants were phenotyped and CRSP2.1 was delimited to ~230 kb on rice chromosome 2. Comparative genomics using a highly contiguous LaGrue genome assembly and annotation identified a cluster of six receptor-like kinase or receptor-like protein genes with highly diverged sequences among rice varieties. A transformation protocol was optimized for LaGrue and CRISPR/Cas9 gene disruption is underway to functionally validate CRSP2.1. Long read sequencing of four additional rice varieties with different CRSP2.1 haplotypes is ongoing to further characterize this genomic locus. Taken together, this study identified strong CRSP2.1 candidate genes likely acting in extracellular pathogen recognition and appear to be under diversifying selection.