Abstract
Stalk rot causes significant yield loss in maize worldwide. The breeding of resistant variety is a potential way to effectively control the disease. This study aims to dissect resistance genes for maize stalk rot caused byFusarium graminearumusing an integrated gene mapping method. A diversity panel of 165 inbred lines and an F2population from the hybridization of CDMA66 and Huangzao 4 were used as materials. The 165 inbred lines were clustered into four subgroups, of which tropical materials are in the majority. Through combining disease severity index (DSI) and single nucleotide polymorphisms (SNPs) of Maize 50K chip and 20K, genome-wide association analysis (GWAS) revealed 34 SNPs that were significantly associated with stalk rot in maize (P< 0.001). These SNPs were distributed on chromosomes 1, 3, 4, 6, 8, and 10, of which the loci on chromosomes 4 and 8 were confirmed by the mapped QTLs for stalk rot. Finally, candidate genes were identified includingGRMZM2G082709which encoded NAC domain-containing protein and thioredoxin reductase (GRMZM5G841142). However, LRR receptor-like serine/threonine-protein kinase (GRMZM2G080041) was down-regulated after inoculation. These SNPs and candidate genes identified would provide essential information for resistant gene cloning and molecular breeding of anti-stalk rot variety in maize.
Highlights
Stalk rot is a destructive disease in maize and occurs worldwide
A week before inoculation, mung beans were put into boiling water for 10 min; after filtering with gauze, mung bean medium were transferred into flasks for sterilization at 121◦C for 30 min. 5–6 Fusarium graminearum clumps with a diameter of about 1 cm were inoculated into 100 ml of mung bean medium
Genetic diversity analysis and genome-wide association analysis (GWAS) about maize stalk rot were performed in a panel of 165 maize inbred lines
Summary
Stalk rot is a destructive disease in maize and occurs worldwide. It has been prevalent in China for decades and causes extensive economic losses (Song et al, 2015). The genetic mechanism of maize stalk rot is complex. It is caused by one or more fungal pathogen(s). The causative agents, including Fusarium graminearum, Fusarium verticillioides, Fusarium moniliforme, Fusarium proliferatum, are soil-borne fungus, indicating it is difficult to control stalk rot. Manual harvest has to be conducted due to the lodging of plants. It is necessary to understand the genetic basis of stalk rot and to breed resistant varieties
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