| Wheat leaf rust, caused by Puccinia triticina, is one of the most important disease which affected worldwide wheat production, and it also seriously affected the wheat production in China. It is adapted to a wide range of climates, occurs wherever wheat is grown, and can cause yield losses of up to 5-15%. It has been proved by practice that resistant cultivars are the most efficient, economic and environmentally-friendly way for reducing losses caused by leaf rust. It is very important to identify leaf rust resistance genes for breeding resistant cultivars. About 66 leaf rust resistance genes have been formally designated in wheat. Most of them confer hypersensitive reactions and interact with the pathogen in a gene-for-gene fashion. The effectiveness of such genes is often short-lived in the field. Currently, only a few designated leaf rust resistance genes, such as Lr9, Lr19, Lr24 and Lr38, are effective against prevalent Chinese Puccinia triticina races. It is very difficult for durable control of leaf rust to wheat in China. It is very important to continuing researching, finding, marking, and using leaf rust resistance genes in China wheat for breeding resistant cultivar and disease protection. The objective of this research was to identify seedling and slow rusting resistance to leaf rust in 104 Xinjiang wheat cultivars of China and find EST maker closely linked with leaf rust resistance gene LrZH84 in Zhou 8425B.A total of 104 Xinjiang winter wheat cultivars and advanced lines and a set of 35 differential near-isogenic lines in the background of Thatcher with known leaf rust resistance genes were inoculated with 12 Chinese pathotypes of Puccinia triticina for postulation of leaf rust resistance genes effective at the seedling stage. These genotypes were also planted in the field for characterization of slow rusting responses to leaf rust in the 2007-2008 and 2008-2009 cropping seasons. Six leaf rust resistance genes Lr1, Lr3ka, Lr14a, Lr26, Lr34, and Lr50, either singly or in combinations, were found in 41 genotypes, whereas known resistance genes were not identified in the other 63 accessions. Resistance gene Lr26 was present in 21 accessions. Lr34 was identified in 17 lines. Genes Lr1 and Lr14a were each detected in three entries. Lr3ka was present in two lines and Lr50 may exist in one line. Seven genotypes showed slow leaf rusting resistance in two cropping seasons.EST (expressed sequence tags) marker is a technique which can detect the DNA mutation from the genome scale by utilizing a particular section of the cDNA clone sequence corresponding to a kind of mRNA derived from different tissues and amplifying the genome DNA specifically through primers designed by their nucleotide sequences. Wheat lines Zhou 8425B give low infection types to most of Chinese current leaf rust pathotypes. In this study, EST markers and BSA were used to mapping leaf rust resistance gene LrZH84 in Zhou8425B. A total of 101 pairs of EST primers on 1B chromosome were used to test the Zhou 8425B, Chinese spring, resistant and susceptible bulks. The results showed that a stable and clear polymorphic EST markers could be amplified between the parents and resistant and susceptible bulks by primer CD373538_cp. The EST marker was designated as CD373538. The polymorphic EST marker was used for analyzing the F2 populations. Linkage analysis was carried out with the software MapManager QTXb20. Results indicated that the dominant resistance gene LrZH84 in Zhou 8425B was closely linked to the EST marker CD373538 located on chromosome 1BL, and the genetic distance detected in the F2 population was 0.4 cM. The marker CD373538 amplified co-dominant polymorphism between resistant and susceptible cultivars. These results indicated that it is a feasible way for establishing molecular markers of wheat leaf rust resistance genes based on EST, and it would provide a basis for the marker-assisted breeding of wheat leaf rust resistance genes in Zhou 8425B. |
PDF Full Text Request