GENETIC ASSESSMENT OF LEAF RUST RESISTANCE IN SOME WHEAT VARIETIES

Abstract

The experiments of this study were carried out through four growing seasons i.e., 2015/16 to 2018/19 at the farm of the faculty of Agriculture, Shibin El-Kom, Menoufia University.Using10 Egyptian wheat varieties,16 wheat promising lines from (CIMMYT) and 20 adult plant leaf rust resistance genes (Lr). lines Lr were used as (male) for crosses with the wheat cultivars (female) to obtain the F1 grains to produce F2 grains and perform genetic analysis. Recording final rust severity (FRS), rate of disease increase (r-value) and the area under disease progress curve (AUDPC) from varieties and lines to responses leaf rust resistance. While STS marker specific for Lr19 and Lr28 genes were performed on the ten wheat varieties and the sixteen promising lines. The responses of rust severity and infection type of the 20 Lr strains were divided into three groups; I resistant genes i.e., Lr17, Lr18, Lr28, Lr 38 and Lr42, II susceptible genes i.e., Lr2c, Lr9, Lr14b, Lr24, Lr34, Lr35, Lr36, Lr37, Lr44 and Lr45, and III genes with variable reactions i.e. Lr2a, Lr19, Lr29, Lr30 and Lr39. Results suggested that genes of group I are important for breeding for leaf rust resistance under Egyptian field conditions. The ten wheat cultivars exhibited low values of FRS and AUDPC except Sids1, and no variety has high rate of (r-value). These cultivars except Sids1 have a good level of adult plant resistance to leaf rust and can be used as resistance sources, 16 wheat promising lines gave lowest values of (FRS), (r-value) and (AUDPC), and consequently they can be used in breeding programs. Genetic analysis showed that Sids1 did not have any of genes under study. However, Gemmeiza 7, Gemmeiza 9, Gemmeiza 10, Gemmeiza 11, Gemmeiza 12, Misr 1, Misr 2, Giza168 and Giza 171 have several Lr genes. Using STS marker specific for Lr19 and Lr28 genes, Lr19 was identified in Gemmeiza 7 and Gemmeiza 11 and Lr28 detected in Gemmeiza 9 and Gemmeiza 10, while Lr19 detected in 13 promising lines, Lr28 found only in five of them. These results showed that molecular markers for Lr genes might be a useful tool in marker-assisted breeding (MAS) for developing Egyptian wheat cultivars.