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PRODUCTION AND CYTOGENETICS OF A NEW THINOPYRUM ELONGATUM / TRITICUM AESTIVUM HYBRID, ITS AMPHIPLOID AND BACKCROSS DERIVATIVES

ABDUL MUJEEB-KAZI¹, ALEJANDRO CORTES², ALVINA GUL¹, MUHAMMAD FAROOQ⁴, FARAH MAJEED¹, IFTIKHAR AHMAD⁴, HADI BUX³, MANILAL WILLIAM², VICTOR ROSAS² AND ROMAN DELGADO²

Abstract: Genetic diversity is crucial for crop improvement. In wheat this resource is distributed within the three gene pools of the tribe Triticeae and priority usage over the last decade has been with the D genome diploid progenitor of the primary gene pool. Potent variability that contributes towards resistance/ tolerance to key biotic/abiotic stresses limiting wheat production is also available in the tertiary pool where Thinopyrum elongatum (2n=2x=14, EE) possesses usable diversity for improving wheat. It has been hybridized with a top quality commercial hexaploid wheat cultivar as the maternal parent in order to capture its cytoplasmic advantage if any and for developing genetic stocks in terms of Th. elongatum disomic chromosome addition lines for identifying positive individual chromosomal contributions towards some key stresses that limit wheat productivity. The F1 hybrid possessed a 2n=4x=28 (ABDE) composition and exhibited predominantly 28 univalents at meiotic metaphase 1. The 28 chromosome F1 hybrid upon pollination with hexaploid wheat gave 2n=7x=49, AABBDDE backcross 1 progeny that upon further backcrossing produced various monosomic A to G addition lines (2n=6x=42 + 1=43) generating monosomic haploids (n=3x=21 + 1=22) by the wheat / maize protocol which were stabilized by colchicine treatment as their respective disomic additions (2n=6x=42 + 2=44). Giemsa C- banding coupled with biochemical and fluorescent in situ hybridization (FISH) were the validation diagnostics for categorization of the disomic addition lines produced. The biochemical applications were to cover one marker per homoeologous group for high molecular glutenins (HMW; Group 1), superoxide dismutase (SOD; group 2), esterase (EST; group 3), alcohol dehydrogenase (ADH, group 4), β-amylase (β-AMY; group 5), glutamate oxaloacetate transaminase (GOT, group 6) and α-amylase (α-AMY, group 7). Th. elongatum possesses diversity for salinity tolerance and for Fusarium head scab resistance. The four disomic addition lines produced (biochemically partial for groups 1, 3, 5 and 7) have rendered this diversity to be used in a targeted fashion around user friendly germplasm after they are categorized for their stress attributes.

¹National Institute of Biotechnology and Genetic Engineering (NIBGE), Faisalabad, Pakistan
²International Maize and Wheat Improvement Center (CIMMYT), Apartado Postal 6-641, Mexico D.F. 06600, Mexico
³Quaid-e-Azam University, Islamabad, Pakistan
⁴National Agricultural Research Center (NARC), Park Road, Islamabad, Pakistan