Document Type : Original Article
Authors
1
Plant Pathology Research Institute, Agricultural Research Center, 12619, Giza, Egypt
2
Field Crop Research Institute, Agricultural Research Center, 12619, Giza, Egypt
Abstract
This research has been carried out to study the disease incidence and genetic analysis of adult plant resistance to leaf rust in eight Egyptian wheat varieties, Misr1, Misr2, Misr3, Gemmeiza11, Gemmeiza12, Sids1, Shandweel 1 and Sakha94 crossed with Triticum spelta saharensis (T.s.s.) as a highly susceptible tester wheat variety at Bahtem Agricultural Research Station, Agr. Res. Center during 2018-2021 growing seasons. The nine wheat genotypes and F2 plants of eight crosses with T.s.s. were estimated to disease incidence measurements and quantitative genetic analysis to leaf rust adult plant resistance. The nine wheat genotypes tested were divided into two resistance groups according to disease incidence measurements (FRS, r-value and AUDPC), the first group having the high and moderate levels of partial resistance i.e., Misr1, Misr2, Misr3, Gemmeiza12, Shandweel 1 and Sakha94, this group is of major importance for efficacious breeding for leaf rust durable resistance, while cultivars Gemmeiza11, Sids1 and T.s.s. were included in the second group with high values of FRS, r-value and AUDPC. The F2 populations, F1 and parents for each of the eight crosses were tested for adult plant disease severity. The quantitative analysis of the F1and F2 mean value of leaf rust severity in the eight crosses was mostly lower than the mean value estimated for their respective mid parents and indicated that rust resistance was partial dominance expecting crosses (T.s.s. × Sids1) in F1 and (T.s.s. × Gemmeiza11) in F2, the positive values were higher than the respective mid-parents, which indicates existence an over- dominance towards susceptibility of these crosses. The heritability in its broad-sense estimated from the variance parents F1and F2 for partial leaf rust resistance, is considered to be high in magnitude, since the values ranged from 63.99 to 96.51%. The number of genes of each analyzed parent is controlled by three, two and a pair of genes. Generality, this outcome in the adult plant stage suggests which selection for this trait may be possible in the first segregating generations. Although the delay would be more efficacious, according to the important role that dominance impacts play in trait expression the selection of resistant adult plants in the subsequent generation of segregation would be useful for the development of a high-yielding wheat genotype under Egyptian condition.
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