568 Wheat Germplasm Resources Screening And PmCG15-009 Exploration And Utilization

Powdery mildew of wheat（Blumeria graminis f.sp.tritici,Bgt）is a fungal disease that critically threatens the yield and quality of wheat.Utilization of host resistance is the most effective and economical method to control this disease.In this study,568 wheat materials were identified for powdery mildew resistance,and 26 showed disease resistance to Bgt isolate E09 among them.Functional markers from Pm1,Pm2,Pm4,Pm5,Pm8,Pm21,Pm24,Pm41,Pm60,Pm69,and linked molecular marker from Pm6detected the associated resistant genes.249 of the 568 wheat materials carried a single known Pm gene,of which two carried Pm1.There are 38 wheat materials containing Pm2,20 wheat materials containing Pm4,26 wheat materials including Pm6,153 wheat materials including Pm8,6 wheat materials including Pm21,and 4 carried Pm60.There were 75 wheat materials containing multiple known Pm genes,of which 65 carried two known Pm genes,8 carried three known Pm genes,and 2 carried four known Pm genes.There were 244 wheat material that did not contain known Pm gene.Among the 26 wheat disease resistance materials,a wheat breeding line Shi CG15-009,released from Hebei Province,was highly resistant to powdery mildew at all stages,and molecular marker analysis showed that it did not carry known Pm genes.To dissect its genetic basis,Shi CG15-009 was crossed with the susceptible cultivar Yannong 21 to produce F₁,F₂ and F_2:3 progenies,and Bgt isolate E09 was used for inoculation identification.After genetic analysis,the resistance to Bgt isolate E09 in Shi CG15-009was controlled by a single dominant gene,tentatively designated as PmCG15-009.Further molecular markers analysis showed that PmCG15-009 was located on chromosome arm 2BL and flanked by markers XCINAU130 and XCINAU143/CIT02g-2with the genetic distances 0.2 and 0.4 c M,respectively,corresponding to a physic interval of 705.14-723.48 Mb referred to the Chinese Spring reference genome sequence v2.1.The resistance spectrum to Bgt analysis showed that Shi CG15-009 showed resistance to15（51.73%）of 29 Bgt isolates originating from different wheat producing areas in China,and was different from other known Pm genes on chromosome arm 2BL.PmCG15-009was most likely a new gene differed from the documented Pm genes on chromosome arm 2BL since its different origin,genetic diversity and physical position.A total of 14 genes associated with disease resistance were annotated in the PmCG15-009 candidate interval,to analyze and identify the candidate genes,six genes associated with disease resistance in the candidate interval were confirmed to be associated with PmCG15-009 via q RT-PCR analysis using the parents Shi CG15-009and Yannong 21 and time-course analysis post-inoculation with Bgt isolate E09（Traes CS2B03G1266900,Traes CS2B03G1269100,Traes CS2B03G1276100,Traes CS2B03G1276200,Traes CS2B03G1283800 and Traes CS2B03G1301600）,may be important candidates/key regulatory genes for PmCG15-009.To better use PmCG15-009 in MAS,20 markers closely linked or co-segregated with PmCG15-009 were tested for their availability in the 46 susceptible wheat cultivars/lines for MAS The results showed that all markers except YTU103-130 and CIT02g-18 could amplify polymorphic bands between Shi CG15-009 and most of the 46susceptible cultivars These results demonstrated that these 18 markers could be used singly or in combination in MAS for tracking PmCG15-009 when transferred into those cultivars.In this study,the wheat Pm gene PmCG15-009 was located and a usable marker for breeding was developed,which provided a new resource for wheat disease resistance breeding.