Inheretance Nature of Leaf Rust Resistance and Some Agronomic Characters in Bread Wheat

Abstract

Wheat leaf rust caused by Puccinia triticina is very destructive to the susceptible wheat (Triticum aestivum L.) cultivars. Breeding for resistance is still the most economic and desirable method for controlling the disease. The objective of this investigation was to: 1) study the nature of inheritance of leaf rust disease resistance as well as grain yield and its related characters, 2) detect leaf rust resistant genes in the studied cultivars under field condition, 3) evaluate using Sequence Characterized Amplified Regions technique (SCAR) for the leaf rust resistance gene Lr37 and 4) use SCAR as a tool for selecting and pyramiding different Lr's resistance genes in Egyptian cultivars. Combining ability effects were estimated using line × tester matting design. Four high yielding cultivars Giza 168, Sakha 93, Sakha 94 and Gemmeiza 9 as females ( lines) and four leaf rust monogenic lines. i.e., Lr10, Lr19, Lr37 and Lr39 as males (testers). Broad sense heritability (h 2 b) was computed. The Chi-square test (χ 2 ) was used to test the significant of difference between observed and expected ratios in F2 populations for leaf rust reaction. PCR reaction for SCAR primers was applied. The study included four characters; plant height (PH), leaf rust resistance as average coefficient of infection (ACI), number of spikes per plant (S/P) and grain yield per plant (GY/P). The obtained results can be summarized as follow; Sakha 93 was the best general combiner for PH and Sakha 94 for leaf rust resistance and GY/P. The best combinations for PH were Giza 168 × Lr39, Sakha93 × Lr19 and Sakha 94 × Lr37; for leaf rust resistance were Sakha 93 × Lr37, Sakha 93 × Lr39, Sakha 94 × Lr10 and Sakha94 × Lr19 and for yield and its components were Sakha 94 × Lr37 and Gemmeiza 9 × Lr19. Giza 168, Sakha 94 and Gemmeiza 9 had one or two genes conferring resistance to leaf rust. In addition, Lr39 leaf rust resistant gene was present in Giza 168 and Sakha 94. The laboratory studies showed that, the SCAR marker has the potential of detecting Lr37 in the studied Egyptian cultivars as well as the monogenic lines. Moreover, Giza 168, line 1 and line 3 had the leaf rust resistance gene Lr37.

Genetic Studies on Stripe and Leaf Rusts of Bread Wheat Under Different Sowing Dates

“…Wheat resistance to rusts has been documented to be a simple inherited character governed by one, two or a few number of major gene pairs (Dyck 1991and Bai et al, 1997. Also, several investigators indicated that resistance is a quantitative character controlled by many genes as well as the prevailing environmental conditions, (Shehab El-Din et al, 1991;Yadav et al, 1998 andNawar et al,2010). Furthermore, the resistance was dominant over susceptibility in most cases, (Shehab El-Din and Abd El-Latif., 1996 ;Bai et al, 1997 andPatil et al, 2000), and vice versa was true in others, (Singh et al, 1998 andGaneva et al, 2001).…”

“…Furthermore, the resistance was dominant over susceptibility in most cases, (Shehab El-Din and Abd El-Latif., 1996 ;Bai et al, 1997 andPatil et al, 2000), and vice versa was true in others, (Singh et al, 1998 andGaneva et al, 2001). On the other hand, some cases best fit a simple additive genetic model with no dominance or epistatic interactions, while dominance and / or epistasis were more pronounced and had important roles, (Shehab El-Din et al, l996;Singh et al, 1998;Zhang et al, 2001;Awaad et al, 2003 andNawar et al,2010).…”