Zhu Jie, Pearce Stephen, Burke Adrienne, See Deven Robert, Skinner Daniel Z, Dubcovsky Jorge, Garland-Campbell Kimberly
Crop and Soil Sciences, Washington State University, Pullman, WA, 99164, USA.
Theor Appl Genet. 2014 May;127(5):1183-97. doi: 10.1007/s00122-014-2290-2. Epub 2014 Mar 14.
The interaction between VRN - A1 and FR - A2 largely affect the frost tolerance of hexaploid wheat. Frost tolerance is critical for wheat survival during cold winters. Natural variation for this trait is mainly associated with allelic differences at the VERNALIZATION 1 (VRN1) and FROST RESISTANCE 2 (FR2) loci. VRN1 regulates the transition between vegetative and reproductive stages and FR2, a locus including several tandemly duplicated C-REPEAT BINDING FACTOR (CBF) transcription factors, regulates the expression of Cold-regulated genes. We identified sequence and copy number variation at these two loci among winter and spring wheat varieties and characterized their association with frost tolerance. We identified two FR-A2 haplotypes-'FR-A2-S' and 'FR-A2-T'-distinguished by two insertion/deletions and ten single nucleotide polymorphisms within the CBF-A12 and CBF-A15 genes. Increased copy number of CBF-A14 was frequently associated with the FR-A2-T haplotype and with higher CBF14 transcript levels in response to cold. Factorial ANOVAs revealed significant interactions between VRN1 and FR-A2 for frost tolerance in both winter and spring panels suggesting a crosstalk between vernalization and cold acclimation pathways. The model including these two loci and their interaction explained 32.0 and 20.7 % of the variation in frost tolerance in the winter and spring panels, respectively. The interaction was validated in a winter wheat F 4:5 population segregating for both genes. Increased VRN-A1 copy number was associated with improved frost tolerance among varieties carrying the FR-A2-T allele but not among those carrying the FR-A2-S allele. These results suggest that selection of varieties carrying the FR-A2-T allele and three copies of the recessive vrn-A1 allele would be a good strategy to improve frost tolerance in wheat.
VRN - A1与FR - A2之间的相互作用在很大程度上影响着六倍体小麦的抗冻性。抗冻性对于小麦在寒冷冬季的存活至关重要。该性状的自然变异主要与春化1（VRN1）和抗冻性2（FR2）位点的等位基因差异相关。VRN1调控营养生长和生殖生长阶段之间的转换，而FR2是一个包含多个串联重复的C - 重复结合因子（CBF）转录因子的位点，它调控冷调节基因的表达。我们鉴定了冬小麦和春小麦品种在这两个位点的序列和拷贝数变异，并表征了它们与抗冻性的关联。我们鉴定出两种FR - A2单倍型——“FR - A2 - S”和“FR - A2 - T”，它们在CBF - A12和CBF - A15基因内由两个插入/缺失和十个单核苷酸多态性区分。CBF - A14拷贝数的增加经常与FR - A2 - T单倍型以及冷处理后更高的CBF14转录水平相关。析因方差分析显示，在冬小麦和春小麦群体中，VRN1和FR - A2之间对于抗冻性存在显著的相互作用，这表明春化途径和冷驯化途径之间存在相互影响。包含这两个位点及其相互作用的模型分别解释了冬小麦和春小麦群体中抗冻性变异的32.0%和20.7%。在一个对这两个基因均分离的冬小麦F4:5群体中验证了这种相互作用。在携带FR - A2 - T等位基因的品种中，VRN - A1拷贝数的增加与抗冻性的提高相关，但在携带FR - A2 - S等位基因的品种中并非如此。这些结果表明，选择携带FR - A2 - T等位基因和三个隐性vrn - A1等位基因拷贝的品种将是提高小麦抗冻性的一个良好策略。
