Identification and Validation of Candidate Genes Conferring Resistance to Downy Mildew in Maize ( Zea mays L.)

• Published in: Genes Vol. 11; no. 2; p. 191
• Main Authors: Kim, Hyo Chul, Kim, Kyung-Hee, Song, Kitae, Kim, Jae Yoon, Lee, Byung-Moo
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI 11.02.2020; MDPI AG
• Subjects: Ascomycota - pathogenicity; Chromosome Mapping; Chromosomes, Plant - genetics; Chromosomes, Plant - metabolism; Databases, Genetic; Disease Resistance - genetics; downy mildew; Gene Expression Regulation, Plant - genetics; Genetic Linkage; maize; Microsatellite Repeats; Oomycetes - pathogenicity; Peronospora - pathogenicity; Peroxidase - genetics; Peroxidase - metabolism; Plant Diseases - genetics; Plant Diseases - microbiology; qrt-pcr; qtl; Quantitative Trait Loci; rils; Up-Regulation; Zea mays - genetics; Zea mays - metabolism; Zea mays - microbiology; QTL; RILs; maize; downy mildew; qRT-PCR
• ISSN: 2073-4425; 2073-4425
• DOI: 10.3390/genes11020191

Downy mildew (DM) is a major disease of maize that causes significant yield loss in subtropical and tropical regions around the world. A variety of DM strains have been reported, and the resistance to them is polygenically controlled. In this study, we analyzed the quantitative trait loci (QTLs) involved in resistance to (sorghum DM), (Java DM) (crazy top DM) using a recombinant inbred line (RIL) from a cross between B73 (susceptible) and Ki11 (resistant), and the candidate genes for , , and resistance were discovered. The linkage map was constructed with 234 simple sequence repeat (SSR) and restriction fragment length polymorphism (RFLP) markers, which was identified seven QTLs (chromosomes 2, 3, 6, and 9) for three DM strains. The major QTL, located on chromosome 2, consists of 12.95% of phenotypic variation explained (PVE) and a logarithm of odds (LOD) score of 14.12. Sixty-two candidate genes for , , and resistance were obtained between the flanked markers in the QTL regions. The relative expression level of candidate genes was evaluated by quantitative real-time polymerase chain reaction (qRT-PCR) using resistant (CML228, Ki3, and Ki11) and susceptible (B73 and CML270) genotypes. For the 62 candidate genes, 15 genes were upregulated in resistant genotypes. Among these, three ( , , and ) and were annotated as leucine-rich repeat (LRR) and peroxidase (POX) genes, respectively. These candidate genes in the QTL regions provide valuable information for further studies related to , , and resistance.