Stripe Rust Resistance Of Parent Lines And Resistance Prediction Of F₁ Hybrids In Wheat

Wheat is one of the three major grain crops in the world.With the decrease of cultivated land area and the increase of population,the utilization of wheat heterosis to increase the yield per unit area is an important way to guarantee food security.Hybrid wheat breeding can ensure high quality and high yield of wheat in a healthier environment and reduce the use of pesticides and environmental pollution.Therefore,it is great significance for stable wheat harvest and green agriculture in China.Wheat stripe rust is a prevalent fungal disease caused by the obligate parasitic fungus Puccinia striiformis f.sp.tritici {Pst),which has caused serious economic losses to global wheat production.Pst mutates rapidly and produces new races every 3-5 years on average.Currently,the resistance to stripe rust of wheat is generally low in China,and new effective resistant source materials are in serious shortage.Therefore,it is great significance to enhance the hybrid wheat breeding against to stripe rust in China.The sterile lines(sterile gene is mslb),restorer lines and F1 hybrids lines are obtained in our laboratory,however,it is still unclear about their resistance to stripe rust and resistance rules between parents and F1 hybrids.There are four races,designating CYR23,CYR31,CYR33 and CYR34 used to identify stripe rust resistance of 21 sterile lines,13 restorer lines and F1 hybrid lines,and the experimental methods include molecular identification of yellow rust(Yr)resistance genes,resistance identification of single race at seedling stage,mixture races at adult stage,and identification of infection of different races at adult stage.The resistance to stripe rust of sterile lines,restorer lines and F1 hybrid lines are evaluated,and the rules of resistance to stripe rust between two generations are summarized,which can provide theoretical basis for hybrid wheat resistance breeding.The main results are as follows:1.The identification of genes and resistance.The resistance genes,Yr5,Yr9,Yrl0,Yr15,Yr17,Yr18,Yr26,are identified by molecular markers or genetic markers.It is found that the Yr genes of their parents are polymerized in F1 hybrids,which is consistent with the genetic rule and indicating that the target genes can be polymerized by molecular marker-assisted breeding.Yr9 exists in the northern lines and Yr26 exists in Sichuan lines.Yr5,Yr1O and Yr15 have not been identified in all the materials,indicating that they are not widely used in wheat resistance breeding in China.Through the identification of resistance in seedling and adult stage,it is found that the parents are resistant,and so is the F1 hybrids,which is consistent with the genetic rule.The higher resistance of parents,the higher resistance of F1 hybrids.Parents and hybrid combinations with high resistance are also obtained,which sterile lines include 15L7152,17L6062,17L6065,17L6067,17L7106,17L7123,17L7140,restorer lines include Chuan14pin16,Chuan13pin6,Chuanmai93,Chuanmai98,MR1101,MY13-3,and the hybrids with the restorer lines from Sichuan.Yr5 and Yr15 are immune to all stripe rust races.Many materials,sterile lines include 15L7152,17L9210,restorer lines include Chuan14pin16,Chuan13pin6,Chuanmai93,Chuanmai98,MR1101,MY13-3 and the hybrids with the restorer lines from Sichuan,are all-stage high resistance based on resistance identification in seedling and adult stage.However,all the resistance genes we detected lost resistance to the CYR34,which indicates that there are unknown resistance genes in these materials.2.Prediction of resistance to stripe rust in F1 hybrids based on parental infection type.According to the identification results of resistance to strip rust in the adult stage,binary regression analysis is conducted with parental infection types as the independent variable and F1 hybrids infection types as the dependent variable,and R2=0.812,which indicates that there is a great correlation between their.At the same time,the unary regression analysis is conducted with the parental infection types average as the independent variable and the F1 hybrids infection types as the dependent variable,and R2=0.740,which indicates that there is a great correlation between their.Therefore,The F1 hybrids resistance to strip rust can be predicted according to the average of the infection types of parental lines.3.Complementary parental resistance can increase F1 hybrids resistance.The quantity of the stripe rust races are determined by using the molecular markers of tested races and semi-quantitative PCR method.The result indicates that CYR23 is not detected in all materials.CYR33 and CYR34 were detected in most materials.Only the restorer lines 15CA50,sterile lines 17L6078 and 15L7128 are infected with a small amount of CYR31.All the tested restorer lines except for Chuan 14 pin 16,Chuan 13 pin 6,Chuanmai 98,Chuanmai 98,MR1101,MY13-3 and their F1 hybrids are infected by both CYR33 and CYR34.Through the detection of F1 hybrids,it is found that the combination of parents with resistance to different races can increase the resistance range of F1 hybrids.In other words,the combination of parents with complementary resistance can increase the F1 hybrids resistance.In summary,high yield,high quality and high resistance materials should be selected as parents in the hybrid wheat resistance breeding,so as to obtain a strong dominant hybrid combination suitable for large-scale application in production.Our findings revealed the rule of disease resistance between parents and their F1 hybrids as well as providing a practical strategy for hybrid wheat disease resistance breeding.