Genetic identification of genes in responses to biotic and abiotic stresses in wheat.

摘要

Biotic and abiotic stresses, such as pest infestation and high temperature, are limiting factors that contribute to wheat production. Hessian fly is one of the most destructive pests of wheat, but little is known about genes controlling the insect. The genes encoding 12-oxo-phytodienoic acid reductase (OPR) and lipoxygenase (LOX) are two genes that play critical roles in the insect resistance pathway in plants. In this study, the Jagger x 2174 derived recombinant inbred line (RIL) population was used to map genes associated with resistance to Hessian fly, and two QTLs were identified. The first one is a major QTL on chromosome 1A (QHf.osu-1A) which explained 70% of the total phenotypic variation; and the second QTL is a minor QTL on chromosome 2A ( QHf.osu-2A), which accounted for 18% of the total phenotypic variation. Mapping of two OPR genes, TaOPR1-A and TaOPR2-A, showed tight association with QHf.osu-1A and QHf.osu-2A, respectively. Manipulation of genes for vernalization response will allow the development of wheat cultivars capable of adapting to higher temperature in changing climatic conditions. Following the cloning of the three vernalization genes, VRN1, VRN2 (ZCCT-1), and VRN3, the molecular diversity of responsive and non-responsive alleles has been investigated. In this study, we used a one-shot PCR to simultaneously amplify the promoter regions of the three ZCCT-1 genes to search for null alleles in hexaploid wheat and discovered null mutants for ZCCT-A1, ZCCT-B1, and ZCCT-D1 among 74 cultivars and genetic stocks of U.S. hexaploid wheat and 54 Chinese wheat cultivars. In addition, we also discovered a novel allele of the dominant Vrn-B1 gene that has a retrotransposon insertion in 5'UTR and confers spring growth habit. The VRN-B1 gene was mapped in a double haploid population derived from two spring tetraploid parents, the durum wheat variety 'Lebsock' carrying the dominant Vrn-A1 and recessive vrn-B1 alleles and T. turgidum subsp. carthlicum accession PI 94749 carrying the recessive vrn-A1 and dominant Vrn-B1 alleles. The retrotransposon insertion was the only difference between the Vrn-B1 and vrn-B1 alleles, and the insertion resulted in expression of Vrn-B1 without vernalization. The potential applications of these genes and mutants for biotic and abiotic stresses in wheat breeding programs and studies on the genetics of wheat are further discussed.