Molecular Mapping Of Leaf Rust Resistance Gene In Wheat Line 5R625 And Zhoumai 22

Wheat leaf rust caused by Puccinia triticina is one of the most serious desease in the world. It can cause yield loss up to 40% or more. With the increasing of temperature and fertilizer, the wheat leaf rust is increasing serious. Using resistant wheat cultivars is an efficient, economic and environmentally safe means to control wheat leaf rust. The wheat line 5R625 and Zhoumai 22 have high resistance to P.triticina at seedling and adult plant stages. phenotype identification and molecular markers were used to identify their resistant gene(s), The main methods and results are as follows: 1) 15 P. triticina pathotypes and 36 wheat lines with known Lr genes were used to to postulate the resistance gene(s) in 5R625.. The result showed that 5R625 might carry Lr9, Lr19, Lr24, Lr28, Lr39, Lr47, Lr51, or Lr53. 2) The P. triticina pathotypes THJP were inclulated to 5R625, Zhengzhou5389 and their F2, F2:3 populations, and the infection types were identified. the F2 population segregated 104 resistant plants and 38 susceptible plants, indicating a single dominant gene for resistance. Among 142 F2:3 families, 40 lines were homozygous resistant, 64 segregated and 38 were homozygous susceptible, fitting a single locus segregation. 3) The Lr5R625 was located on 3DL chromosome by polymorphic molecular markers with F2:3 families. Among the five closely linked molecular markers to the resistance gene in 5R625, STS marker 24-16 and SCAR marker OP-J09 were proved co-segregated with Lr24, therefore the resistance gene in 5R625 is most likely Lr24. 4) by infection type identification and molecular markers detection, the adult plant leaf rust resistance in 5R625 is controlled by a single dominant gene which is Lr24 alike. 5) The mixture of P. triticina pathotypes were inculated to the F2, F2:3, F2:4 populations from the cross Zhoumai22/Chinese Spring, 1200 molecular markers were screened between parents and small resistant and susceptible groups, polymorphic markers were used to detect the 215 F2:3 lines. Phenotypic and genotypic data were combined to make the linkage groups and QTLs analysis by the softwares QTL Mapmanager QTXb17 and Ici Mapping 3.1. Three QTLs were found on chromosomes 2BS, 4B and 7DS during each crop season from 2012 to 2014. 6) The QTL on chromosome 2BS comes from Zhoumai 22, and explained 12.96%, 12.58% and 13.58% of the phenotypic variation respectively in the year 2012, 2013 and 2014. The QTL on 4B most likely be Lr12, and it comes from Chinese Spring, explained 7.02%, 10.67% and 20.22% of the phenotypic variation respectively in the three years. The QTL on 7DS also comes from Chinese Spring, It is Lr34, and explained 20.87%, 21.30% and 6.73% of the phenotypic variation respectively. 7) The QTL on chromosome 2BS may be a new leaf rust resistance gene, Further study should be done to test if other QTLs woked in Zhoumai 22.