Analysis Of Wheat Leaf Rust Resistance Of 14 Wheat Cultivars

Wheat leaf rust caused by Puccinia triticina is one of the important diseases of wheat in China. It can cause a pandemic in a short time and cause yield losses of 5% to 45% or more on susceptible wheat in commercial cultivars. Uilization of the resistant cultivars is the most economical, effective and safely way for controlling the wheat leaf rust. The newly appeared races of pathogens or the secondary races became the pandemic races made the cultivars easy lose resistance. Therefore, identification of resistance genes, polymerization of multiple resistance genes and resistance breeding are important tasks to prevent and control wheat leaf rust effectivly.In China, the resources of wheat are rich for breeding and genetic research. However, wheat leaf rust resistance genes in the riching wheat resources are not known well till now, because the identification and location of wheat leaf rust resistance gene reseach works were carried out later than some countries and international organizations. The objective of the research is to evaluate the leaf rust resistance and identify the resistance genes of the 14 wheat cultivars (lines). The results are as follows:1. Resistance evaluation and resistance gene postulation of the 14 accessions were carried out with 16 races with different virulences of Puccinia triticina at seedling stage. Thatcher near-isogenic lines were used as testers for known resistance genes. The results showed that the 14 accessions displayed different levels of rust resistance to the inoculated leaf rust races. 916-8-18, 9916-8-6, 00-55-3-1-1, 96104-1-5-1c2, 9524-1-2-2-1, 97167-1-2-1-1-2-1 and 9629-03A-4-1-1 had different infection type patterns with the near-isogenic lines (NILs). They might carry unknown resistance genes or other known resistance genes to wheat leaf rust which were not used in the tester lines. 1R35 and s98351-2-2-2-1 might contain Lr3a and Lr50. Mianzhong438 and 919-20-2c2 were supposed to contain Lr42 and 9589 probably have Lr24, Lr28 and Lr38. 1R17 and 1R13 possessed Lr19, Lr24, Lr28 and Lr38.2. Sixteen races of P. triticina were mixed and inoculated the test accessions in field to detect the field reaction to wheat leaf rust at adult stage of the 14 accessions. Among them, 9916-8-18, 9916-8-6 and 00-55-3-1-1 displayed high infection type(IT) of"4", and with less than 30 disease index. They belonged to slow rusting type and accouted for 21% of tested materials. 1R35, 1R17, 1R13, Mianzhong438, 9589, 96104-1-5-1c2, 9524-1-2-2-1, 919-20-2c2, 97167-1-2-1-1-2-1, 9629-03A-4-1-1 and s98351-2-2-2-1 displayed low IT of";"or"1", and conferred nearly immune or highly resistant level, and accouted for 79% of tested accessions.3. Twenty one molecular markers closely linked or co-segregated with Lr1, Lr9, Lr10, Lr19, Lr20, Lr21, Lr24, Lr26, Lr28, Lr29, Lr34, Lr35, Lr37, Lr38, Lr42 and Lr47 were employed to molecular assisted identify the wheat leaf rust resistance genes. The specific fragments of Lr1, Lr10, Lr24, Lr26, Lr28, Lr34, Lr37 and Lr38 were detected in the test genotypes either alone or in various combinations. However, the others had no target products.4. The synthetical resistance analysis indicated that Lr10 and Lr34 were present in 1R35, and Lr3a and Lr50 possibly in 1R35, Lr24 and Lr38 possibly in 1R17, Lr24, Lr37, and Lr38 possibly in 1R13, Lr1 in 00-55-3-1-1. Lr28 was postulated present in 96104-1-5-1c2, Lr37 possibly in 9629-03A-4-1-1. Lr28, Lr3a, and Lr50 were possible in s98351-2-2-2-1. Lr26 was present in 6 accessions including 9916-8-18, 9916-8-6, Mianzhong 438, 9589, 919-20-2c2, and 97167-1-2-1-1-2-1. Genes Lr9, Lr19, Lr20, Lr21, Lr29, Lr35 and Lr42 were not present in all cultivars (lines) according to their specific markers.The results indicated that the 14 cultivars (lines) carried diverse resistance genes to leaf rust. Mianzhong438, 9589, 96104-1-5-1c2, 9524-1-2-2-1, 919-20-2c2, 97167-1-2-1-1-2-1, 9629-03A-4-1-1 and s98351-2-2-2-1 displayed excellent resistance to wheat leaf rust, and showed good potential in wheat production. 1R35, 1R17 and 1R13 contained richer leaf rust resistance genes and displied higher resistance than others, and could be as resistance resource for resistance breeding. The results provide an important basis for the rational distribution of wheat cultivars and the rational use of breeding resources.