MOLECULAR ANALYSIS OF NEW DROUGHT TOLERANT SEGREGANTS SELECTED FROM F₂ POPULATIONS OF BREAD WHEAT CROSSES

AL-NAGGAR A.M.M.¹, AL-AZAB KH.F.², SOBIEH S.E.S.³, ATTA M.M.M.^4
1Department of Agronomy, Faculty of Agric., Cairo University, Giza, Egypt.
²Plant Res. Dept., Nuclear Res. Center, Atomic Energy Authority, Inshas, Egypt.
³Plant Res. Dept., Nuclear Res. Center, Atomic Energy Authority, Inshas, Egypt.
⁴Department of Agronomy, Faculty of Agric., Cairo University, Giza, Egypt.

Received : 26-11-2013     Accepted : 27-02-2014     Published : 24-04-2014
Volume : 3     Issue : 1       Pages : 58 - 69
World Res J Agron 3.1 (2014):58-69

New genetic recombinations in bread wheat hybrid populations are considered the main source of variation for practicing successful selection to develop drought tolerant genotypes. Diallel crosses (except reciprocals) among six wheat cultivars and lines were made in 2008/2009 season. F2 seeds were produced on F1 plants in 2009/2010 season. Selection for high grain yield was practiced in the F2 populations in 2010/2011 season under water stress (WS) and well-watering (WW) conditions. The selected 115 F3 families and their 6 parents were evaluated in the field in 2011/2012 season under both conditions. Among them, five F3 families showed superiority under WS reaching 61.8% for SF9 over the best Egyptian cultivar in this study (Sakha-93). Molecular characterization based on simple sequence repeats (SSR) analysis of the 5 best recombinants (drought tolerant) and their five parents was performed. The 15 SSR primers produced 42 amplicons, 34 of them were polymorphic, with an average polymorphism of 78.59%. Ninety two amplicons were useful genotype–specific markers for the studied 10 wheat genotypes, in which 56 of them were positive, while 36 were negative markers. The 5 selected recombinants (SF8 through SF12) exhibited 3,1,2,6 and 11 positive markers and 8,5,4,2 and 6 negative markers, respectively. The SSR assay permitted the identification of two out of ten wheat genotypes by six unique markers. Maryout-5 and Aseel-5 were characterized by four positive unique markers, while maryout-5 was characterized by one negative unique marker. The Syrian drought tolerant cultivar Aseel-5 was characterized by two unique positive markers amplified by the primers WMS 198 (100bp) and WMC 322 (400bp). The genetic similarity ranged from 57 to 84%, suggesting that the new recombinants are different from their parents on the DNA level.