Basis of Karnal bunt resistance in diploid and tetraploid Triticeae species

摘要

Karnal bunt (KB) is one of the most important post-harvest disease of wheat. Although the extent of damage caused by KB is low in terms of grain yield still, the disease is of greater concern because of restrictions in the international trade among the wheat-growing countries. Control of KB is difficult and the only sustainable method for disease control is the deployment of host resistance. Since KB resistance in the hexaploid wheat i.e., Triticum aestivum is partial. Further, diploid (dicoccoides and aegilopids) and tetraploids wheat species have been reported to possess high level of field resistance to KB, hence, there is a need to explore their basis of resistance. Therefore, the present study was conducted to study morphological basis of resistance in representative diploid ( T. monococcum , T . urartu , T . boeticum , Aegilops tauschii ) and tetraploid ( T . dicoccum , T . ararticum ) wheat species, by correlating compactness of spike, stomatal frequency, and hair count on the glumes with disease severity. The compactness of spike and stomatal frequency played no role while hair count on glumes might act as a morphological barrier for the pathogen responsible for KB. Further, histopathological observations of diploid and tetraploid species confirmed the resistance reaction in T . monococcum , T . boeticum , and Ae . tauschii which may be due to higher hair count on glumes.