| Poplar is one of the most important afforestation tree species in the urban greening, industrial wood and ecological protection, but their growth and timber production were affected by the drought stress seriously. Therefore, it is important to breed a drought-resistant, fast-growing poplar species. In this study, we selected the hybrid P. deltoides cv. ‘Danhong’, a newly breed fast-growing American black poplar, as the female parent, and the local strong resistance species P. simonii as the male parent. After artificial hybridization, the drought-related properties and genetic information of the hybrid offspring were analyzed. In addition, the SSR molecular marker were screened. This study lay a foundation of the molecular marker assisted breeding selection and drought-resistant species breeding. The main conclusions were listed as follows:The artificial hybridization was based on the female parent – hybrid P. deltoides cv. ‘Danhong’ and male parent – P. simonii.Total of 367 F1 offspring were obtained. The two parents and 137 F1 offspring were selected for drought stress, and the relative water contents(RWC), chlorophyll SPAD, leaf areas, and photosynthesis were analyzed.The two parents showed great differences at aspects as growth rate, photosynthesis, and drought tolerance. Under normal water conditions, the height, diameter, net photosynthetic rate, leaf area, transpiration rate, intercellular CO2 concentration, and stomatal conductance of P. deltoides CL.‘Danhong’was higher than P. deltoides CL.‘Danhong’;but relative water content, water use efficiency, stomatal limits is lower than P. deltoides CL.‘Danhong’. The T test results showed that there were significant differences(P<0.05) between the diameter and the transpiration rate; between the the stomatal conductance, net photosynthetic rate, leaf area, intercellular CO2 concentration and the relative water content had significant difference(P <0.01). Under drought stress, in addition to water use efficiency and stomatal limitation value increased, the other characters of P. deltoides CL.‘Danhong’and P. simonii are showing a downward trend. The drought related coefficient of net photosynthetic rate, transpiration rate, intercellular CO2 concentration of P. deltoides CL.‘Danhong’ were 46.07%, 37.10% and 21.56%, significantly lower than P. simonii 73.55%, 49.06% and 30.50%, indicating that the photosynthesis of P. deltoides cv. ‘DanHong’ were highly affected by the drought stress.Under both normal and drought stress conditions, each trait of the offspring had extremely significant differences. Most traits were decreased under drought stress, indicating that the phenotype related growth and photosynthesis were inhibited in the offspring. The coefficient of variation of drought tolerance in the offspring were ranged about 0.08-0.62 under normal condition and 0.07-0.60 under drought stress condition, respectively.Principle component analysis of the drought-tolerance coefficients indicated that the net photosynthesis rate and RWC were highly connected with the drought tolerance, followed by the seedling height, basal stem diameter, leaf area and chlorophyll content. The membership function method in fuzzy mathematics was used to comprehensive evaluating the drought tolerance of parents and F1 offspring. Based on the clustering analysis, the offspring could be classified into three types: strong drought tolerance(43 lines), moderate drought tolerance(72 lines) and weak drought tolerance(24 lines).We obtained 3 good offspring which grow fast and be strong drought tolerance,it was 99, 186, 300.Based on the publicly poplar genome database, total of 800 pairs SSR primers were used for primer selection. After the capillary electrophoresis, 80 pairs were selected for polymorphism analyses. These selected SSR primers could be used in the hybrid population genetic analysis and the molecular marker assistant breeding in the future. |
PDF Full Text Request