INHERITANCE OF RESISTANCE TO FLAG SMUT (UROCYSTIS-AGROPYRI) IN WHEAT (TRITICUM-AESTIVUM) LINES

Inheritance of resistance to flag smut caused by Urocystis agropyri (Preuss.) Schroet. was studied in 5 highly resistant lines of wheat (Triticum aestivum L. emend. Fiori & Paol.), viz 'CI 14394', 'CPAN 1425', 'E 8640', 'HS 86' and 'WL 410'. Quantitative estimates of the number of genes segregating for disease resistance revealed that 9-10 large-effect genes controlled the resistance to flag smut in 'E 6840', 3-4 in 'WL 410' and 2-3 each in 'CI 14394', 'CPAN 1425' and 'HS 86', in addition to some small-effect resistance genes or modifiers. Susceptible parent 'Agra Local' also had 1 or more small-effect genes for resistance to flag smut. Presence of dominance, epistasis or linkage among the resistance genes was detected in 'CI 14394', 'E 6840', 'HS 86' and 'WL410'. 'CI 14394' had 1 or more large-effect resistance genes, different from those in 'HS 86' but similar to those in 'E 6840'. Likewise, 'E 6840' had resistance genes, different from those in 'WL 410' but similar to those in 'CPAN 1425'. The presence of many major genes and their modifiers controlling resistance to flag smut in the wheat lines studied here could be an important factor for the durability of resistance.