The Analysis Of Stomatal Traits And QTL Mapping Under Drought Condition In ’Qinguan’×’Honeycrisp’ Leaves

Northwest is not only the best apple-producing areas in China, but also the largest areas, Water scarcity is a major factor limiting its development of apple industry. Drought resistance breeding for the promotion of quality high and stable yield is of great significance.Stomata which existed in the surface of leaves control the exchange of gases(water vapor and CO2) between the leaf interior and atmosphere, thus they are capable of influencing many aspects of plant growth and metabolism. Stomatal characteristics closely related to drought resistance is a very important form of indicators in many plants. In this research, The offsprings of cross between’’ Qinguan’’ and ’’ Honeycrisp’’ were used to study the inheritance of stomatal traits under two different water stress. We analyzed the stomatal traits, and then detected the QTLs for them. All of this provide a deeper theoretical basis for drought resistance breeding. The main results are as follows:We analyzed the stomatal traits in ’ Qinguan’ and ’ Honeycrisp’ under two different water stress. We found that under control condition, the stomatal density of ’ Honeycrisp ’ was 1.15 times as ’ Qinguan’, but both the stomatal length and width were 80%, 79% of ’ Qinguan’, respectively. Meanwhile, under drought stress, the stomatal density of ’ Qinguan’ had a substantial increase, increased by 50%, ’ but both the stomatal length and width had a decrease, decreased by 12%, 16%, respectively. ’ Honeycrisp ’ had an opposite condition. The stomatal density, length and width of ’ Honeycrisp ’ was decreased by 7%, 17% and 16%, respectively. This indicates that the stomatal traits are connected with cultivars genes.We analyzed the leaf stomatal traits of the offsprings of cross between’ Qinguan’ and ’ Honeycrisp’. Compared with control condition, under drought stress, their leaf stomatal density increased by 20% and the stomatal length and width decreased by 12% and 5%, respectively. At the same time, we made the frequency distribution of stomatal traits. We found that they obeyed the normal distribution, and met the requirements of QTL analysis.We located the QTLs for stomatal traits by a SNP linkage maps provided by our laboratory. We found 13 QTLs at the LOD threshold > 3 level.. Among this, under control condition, there were 2 QTLs for stomatal density, 3 QTLs for stomatal length and 1 QTLs for stomatal width. Under drought stress, 3 QTLs for stomatal density, and 3 QTLs and 1 QTLs for stomatal length and width, respectively were found.