Molecular Breeding of Winter Wheat Cultivars Adaptive to Changing Climate.

Molecular breeding of winter wheat cultivars adaptive to changing climate Liuling Yan and Brett Carver Department of Plant and Soil Sciences, Oklahoma State University, Stillwater, OK 74078, USA Current scientific consensus is that global climate will unavoidably produce significant change in two major environmental factors, temperature and photoperiod. Global warming, a projected 3°C average temperature increase by the end of this century, will greatly affect the production of many crops, including wheat. Winter wheat requires a period of exposure to low temperatures ranging from 2-10°C, a process known as vernalization, to accelerate its ability to flower. Therefore, winter wheat development is extremely vulnerable to higher temperatures in the future climate scenario. Warmer temperature will increase growth rate in any season due to a shorter phyllochron, resulting in earlier development; however higher temperatures in winter seasons will lead to insufficient or failed vernalization and subsequent yield loss of winter wheat. Using recombinant inbred lines of two populations generated from locally adapted winter wheat cultivars, we discovered that initiation of stem elongation and maturity of winter wheat are regulated by two genetic loci at VRN-A1 and VRN-D3; however, both of them were cloned based on variation in vernalization requirement between spring wheat and winter wheat. This has shed new light on molecular mechanisms of two known genes involved in the regulation of development in winter wheat, or alternatively, on novel genes close to VRN-A1 and VRN-D3. Photoperiod also has multiple effects on wheat growth and development. We discovered a new QTL on chromosome 7D that has a highly significant effect on reproductive development in winter wheat. Putting these known and new genetic loci together with PPD-B1 and PPD-D1 which also influence winter wheat growth and development, a gene network is established to explain the complex and paradoxical effects of temperature and photoperiod on winter wheat development. With perfect markers for these genes/QTLs, new winter wheat cultivars will be bred to avoid or minimize frost injury due to precocious development or heat damage associated with later maturity and withstand the adverse effects projected with future climate scenarios.