| Leaf veins,made up of vascular bundle,are important parts of plant leaves and play a key role in transporting water and supporting leaves.The leave veins of gramineous plants mainly include the diameter,distance and density of veins.These traits determined the hydraulic conductivity of vein and transport capacity of photosynthetic product and nutrients,thus affecting the supplying and using of plants.During the drought conditions,plants can reduce the damage by changing the traits of leaf veins.However,the molecular mechanism and morphogenesis of leaf vein has not been reported in foxtail millet.In this study,320 core germplasms of foxtail millet were selected as experimental materials and planted in Shanxi Agricultural University,the third leaf from the top of plant was selected at the heading stage for vein analyzing,and then correlation analysis and feature analysis of these traits were performed in this study.Based on the data of genome re-sequencing,the ten phenotypic traits and the selected high-quality single nucleotide polymorphisms(SNPs)were analyzed by genome-wide association study.In order to study the contribution of leaf vein traits to the drought resistance of foxtail millet,32 representative varieties were selected from the core germplasms of foxtail millet for drought resistance identification at seedling stage.These results will provide the theoretical foundation for breeding new species of foxtail millet by improving leaf veins.The main findings are as follows:1.The mesophyll tissue on either side of major vein were distributed with all levels of leaf veins,from foliar base to apex,thick veins alternate with thin veins.Such as diameter,distance and density of leaf veins,etc.have plenty of genetic variation.The results of correlation analysis showed that there was significant negative correlation between density and spacing,distance,and there was significant positive correlation between spacing and distance.2.A total of 57 SNP were detected to be significantly correlated with 10 traits of leaf veins by genome-wide association study.All the genes in the 50 kb interval upstream and downstream of SNP sites were annotated by NR,GO and KEGG databases.Through the annotation information,a total of 4 candidate genes Si6g09080,Si8g10750,Si7g07770,Si1g04020 were predicted to be related to the density of leaf veins,3 candidate genes Si1g22670,Si1g22680,Si2g04100 were predicted to be related to diameter of leaf veins,3 candidate genes Si9g12210,Si6g23190,Si5g39810 were predicted to be related to the distance of leaf veins.3.We measured the relative chlorophyll content,relative leaf water content and Fv/Fm of the foxtail millet seedlings under control and drought treatment.and found that the greatest effect on the chlorophyll content and relative leaf water content under the drought condition,the drought resistance of 32 foxtail millet materials at seedling stage was divided into four grades: strong drought resistance,medium drought resistance,weak drought resistance and drought sensitive.However,the contribution of leaf veins to the drought resistance of foxtail millet was not defined. |
