| Tartary buckwheat（Fagopyrum tataricum G.）is a traditional food crop in China.It originated in Southwest China.Its wild type is mostly distributed on rocky hillsides and has strong drought resistance and barren resistance.However,there are few related reports.Identifying drought resistance of Tartary buckwheat germplasm and mining drought resistance genes and molecular markers in Tartary buckwheat germplasm resources are important contents of Tartary buckwheat genetics and breeding.In this study,247 Tartary buckwheat germplasm resources were used as materials to study their agronomic characters,response under water stress and SSR molecular markers.The main results are as follows:1.Evaluation of agronomic characters:（1）Based on the investigation of 13 main agronomic characters of219 Tartary buckwheat materials,including plant height,main stem branches,number of main stem nodes,number of grains per plant,grain weight per plant,1000 grain weight,grain length,grain width,grain length width ratio,grain perimeter,grain diameter,grain area and growth period,it was found that the genetic diversity of Tartary buckwheat germplasm resources was rich,and the coefficient of variation of each agronomic character ranged from 9.62% to 53.36%.The genetic diversity of grain weight per plant was more abundant than that of other indexes.The coefficient of variation of grain number per plant is 47.32%,with the mean value of 217.16;The coefficient of variation of grain weight per plant was 53.36%,with an average of 4.28 g.The genetic diversity and richness of grain width,grain diameter and whole growth period were low.The coefficient of variation of grain width is 9.62%,and the mean value is 3.15 mm;The coefficient of variation of grain diameter is 11.62%,with an average of 3.81 mm;The coefficient of variation in the whole growth period is 10.21%,with an average of 67.55 days.The variation degree of other characters was medium.（2）The tested Tartary buckwheat can be divided into four categories according to ploidy,domestication degree and shell thickness,namely conventional cultivated Tartary buckwheat（conventional Tartary buckwheat）,thin shell Tartary buckwheat（rice Tartary buckwheat）,wild Tartary buckwheat and Tetraploid Tartary buckwheat.Among them,wild Tartary buckwheat has the most abundant genetic diversity,and the coefficient of variation of various agronomic traits is between7.19%~55.08%.It is a high-quality resource pool for Tartary buckwheat breeding.The average plant height and whole growth period of wild tartary buckwheat are 39.84 cm and 66 d,which is significantly lower than other types of Tartary buckwheat.It has the characteristics of short plants and short growth period.The comprehensive performance of all indexes of conventional Tartary buckwheat is the best.The average values of agronomic characters such as plant height,number of main stem nodes,number of main stem branches,number of grains per plant and grain weight per plant are 80.43 cm,13.34,5.90,243.96 and 5.07 g respectively,which are significantly higher than other types of Tartary buckwheat,and the average value of the whole growth period is 63.99 days,which has no significant difference with wild Tartary buckwheat.The 1000 grain weight,grain area,grain perimeter,grain length width ratio,grain length and grain width of Tetraploid Tartary buckwheat are significantly higher than those of other types of Tartary buckwheat,with the average values of 25.47 g,17.20 mm2,18.08 mm,2.00,7.07 mm and3.58 mm respectively.It is a Tartary buckwheat material with extremely prominent grain character advantages.The mean values of plant height,branch number of main stem,node number of main stem and grain number per plant of rice Tartary buckwheat are 81.04 cm,6.25,12.84 nodes and 236.41 respectively,which are close to the conventional Tartary buckwheat and significantly higher than other types of Tartary buckwheat.The mean values of grain weight per plant,1000 grain weight,grain area,grain perimeter,grain length width ratio,grain length and grain width are 3.15 g,13.12 g,9.19 mm2,12.23 mm,1.53,4.48 mm and2.95 mm respectively,which are significantly lower than other types of Tartary buckwheat,It shows that thin shell Tartary buckwheat is actually a high-yield Tartary buckwheat,which is the illusion that its thin shell leads to its low yield.（3）Using simple correlation analysis and partial correlation analysis,it is found that there is a positive interaction between the number of grains per plant and the weight of grains per plant,the number of branches and nodes of main stem,and the number of nodes of main stem.The breeding purpose can be achieved only by improving a certain character,which greatly improves the efficiency of breeding.Principal component analysis showed that 13 main agronomic traits could be reduced to four main factors,namely grain factor I,yield factor,growth period factor and grain factor II.（4）Based on the synthesis of principal component analysis and cluster analysis,13 agronomic characters were evaluated,and one quadruple Tartary buckwheat xyf11 with prominent grain characters and10 Tetraploid Tartary buckwheat XYF115,XYF28,XYF26,XYF25,XYF33,XYF39,X44,XYF40,X34 and XYF27 with good comprehensive characters are obtained.10 Tartary buckwheat materials with good comprehensive characters,high yield and early maturity areelomulja,jinku No.6,liangku-4,Qianku No.3-1,miqiao（light color）,r139,R138,1808-104m10,Pingqiao No.7 and r90.Ten dwarf materials such as R216,R154,R167,R214,R364,R221,R237,R366,R179 and R152,and ten dwarf lodging resistant materials with good comprehensive properties such as R177,R217,R202,R155,R363,R157,R170,R159,R158 and R355 are obtained.2.Drought resistance evaluation of Tartary buckwheat:（1）By using 20% PEG-6000 to simulate drought stress,it is found that the variation coefficients of relative germination rate,relative germination potential,relative radicle length,relative germ length,relative germination index and relative vigor index are large,ranging from 67% to 122%,and are significantly correlated with the average membership function value,which could be used as the drought resistance evaluation index of Tartary buckwheat during germination;The coefficient of variation of relative fresh weight of true leaves,relative dry weight of true leaves,relative water content of true leaves,relative fresh weight of stems,relative dry weight of stems,relative water content of stems and relative plant height are between 13%~69%,and are significantly correlated with the value of average membership function,which can be used as the drought resistance evaluation index of Tartary buckwheat at seedling stage.（2）The drought resistance of 156 Tartary buckwheat sprouts and 74 Tartary buckwheat seedlings were identified by multi index and membership function method.Five materials with strong drought resistance during germination were selected,including Ningxia conventional cultivated Tartary buckwheat（Ningqiao No.2）,Yunnan conventional cultivated Tartary buckwheat（Yunqiao No.2）,Shanxi conventional cultivated Tartary buckwheat（R105）,Sichuan conventional cultivated Tartary buckwheat（Chuanqiao No.1-1）,Tibet wild Tartary buckwheat（R217）.Six materials with strong drought resistance during germination were selected,including Shanxi conventional cultivated Tartary buckwheat（R138,R58）,Guizhou conventional cultivated Tartary buckwheat（Fangyuancai kuqiao,2000 r,Dakuqiao）Guizhou thin shell Tartary buckwheat（Hemi B）;There were 14 strong drought resistant materials in the seedling stage,including Shanxi conventional cultivated Tartary buckwheat（R138,R58,Jinqiao No.2）,Gansu conventional cultivated Tartary buckwheat（Pingqiao No.6,hemp Tartary buckwheat）,Guizhou cultivated Tartary buckwheat（Hunya）,Guizhou thin shell Tartary Buckwheat（guiheimi 3,Mi11）,Guizhou tetraploid Tartary buckwheat（Mi55-4T,XYF39,XYF69,Changhei 4T）,Sichuan conventional cultivated Tartary buckwheat（Chue）and Tibet wild Tartary buckwheat（R222）.（3）Physiological study on Drought Resistance of Tartary buckwheat:Taking 74 representative Tartary buckwheat materials as materials,the physiological indexes such as SOD were analyzed.The results showed that under drought stress,the increase of SOD and pod enzyme activities in the true leaves of Tartary buckwheat could slow down the damage caused by drought stress.3.SSR molecular marker association analysis:SSR molecular marker association analysis was performed on 94 Tartary buckwheat using 41 pairs of SSR primers with high polymorphism.The association analysis showed that there are 16 loci significantly associated with agronomic traits and 29 loci associated with drought resistance indexes.Among them,2 loci are highly significantly associated with main stem branches and grain characters of Tartary buckwheat,and 14 loci associated with drought resistance indexes showed multiple associations in the correlation analysis between control group indexes,drought stress indexes and relative indexes and SSR molecular markers. |
