Gene Mapping and Identification of a Missense Mutation in One Copy of VRN-A1 Affects Heading Date Variation in Wheat

Abstract

Heading date (HD) is an important trait for wide adaptability and yield stability in wheat. The Vernalization 1 (VRN1) gene is a key regulatory factor controlling HD in wheat. The identification of allelic variations in VRN1 is crucial for wheat improvement as climate change becomes more of a threat to agriculture. In this study, we identified an EMS-induced late-heading wheat mutant je0155 and crossed it with wide-type (WT) Jing411 to construct an F2 population of 344 individuals. Through Bulk Segregant Analysis (BSA) of early and late-heading plants, we identified a Quantitative Trait Locus (QTL) for HD on chromosome 5A. Further genetic linkage analysis limited the QTL to a physical region of 0.8 Mb. Cloning and sequencing revealed three copies of VRN-A1 in the WT and mutant lines; one copy contained a missense mutation of C changed to T in exon 4 and another copy contained a mutation in intron 5. Genotype and phenotype analysis of the segregation population validated that the mutations in VRN-A1 contributed to the late HD phenotype in the mutant. Expression analysis of C- or T-type alleles in exon 4 of the WT and mutant lines indicated that this mutation led to lower expression of VRN-A1, which resulted in the late-heading of je0155. This study provides valuable information for the genetic regulation of HD and many important resources for HD refinement in wheat breeding programs.

The Effects of Vernalization and Photoperiod Genes Composition on Heading Date in Wheat

“…Heading date is an important factor determining the adaptability of diff erent wheat varieties to local climatic conditions and environmental stresses [32,33]. Flowering is one of the most critical developmental transitions in plant life, which initiates the switch from vegetative to reproductive development.…”

“…A key step in wheat phenological development is the initiation of fl owering, also known as heading date, which is defi ned as the time when the main stem spike of a single wheat plant emerges from the leaf sheath by 1/2 [35]. Heading date directly aff ects wheat yield, and therefore is an important characteristic to consider when breeding new varieties [33].…”

Allelic Variations in Vernalization (Vrn) Genes in Triticum spp.

“…Phenology is a key target for adapting wheat varieties to ongoing climate changes and Vrn genes play a crucial role in accelerating reproductive development after prolonged exposure to low temperatures during the winter [85,[114][115][116][117]. Matching the development phases and growth of the wheat crop to the thermal regime of the growth environment allows us to maximize the exploitation of natural resources by limiting climatic stress.…”