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AEGILOPS TAUSCHII, AS A SPOT BLOTCH (COCHLIOBOLUS SATIVUS) RESISTANCE SOURCE FOR BREAD WHEAT IMPROVEMENT

A. MUJEEB-KAZI ¹, ALVINA GUL¹, IFTIKHAR AHMAD ², MOHAMMAD FAROOQ², SUMAIRA RIZWAN³, HADI BUX³, SHAMIM IFTIKHAR², SHAHZAD ASAD² AND ROMAN DELGADO⁴

Abstract: Cochliobolus sativus the cause of Spot blotch, affects wheat crops across several environments globally with Bangladesh being represented as a major disease location. Accessional diversity in conventional germplasm was limited until the mid-eightees with BH-1146 being most popular. With the novel usage of exotic germplasm emerging in that decade, wide cross programs got popularity and the release of the intergeneric cross product “Mayoor” initiated additional efforts around this new genetic diversity resource of the wheat family Triticeae. Derivatives of Mayoor known as Chirya added another dimension and then on the scene came the D genome contribution of the diploid progenitor Aegilops tauschii (2n=2x=14). Synthetic hexaploid wheats (SH) derived from crosses between Triticum turgidum x Ae. tauschii (2n=6x=42; AABBDD) became a popular germplasm source for tests against various wheat production constraints around biotic and abiotic stresses and these provided superior resistance to C. sativus either alone or also in SH x SH combinations due to gene pyramiding. From the earlier resistance scores of 9-5 vs 9-9 for susceptibility the SH germplasm was from 9-2 or 9-3 to pyramided lines with 2-2 or 3-2. The latter translated to the same 2-2 or 3-2 levels when these superior SH’s were crossed onto elite bread wheat cultivars susceptible to C. sativus. Further, the resistant stocks derived from both the intergeneric and interspecific avenues gave seed finish readings of 1 or 2 vs the 4 or 5 susceptible germplasm scores. This paper elucidates data of the above three categories of C. sativus tests done under stringent field conditions over several years of evaluations.

¹National Institute of Biotechnology and Genetic Engineering (NIBGE), Faisalabad, Pakistan

²National Agricultural Research Center (NARC), Islamabad, Pakistan

³Quaid-e-Azam University, Islamabad, Pakistan

⁴International Maize and Wheat Improvement Center (CIMMYT), Mexico D. F., Mexico