Morphological and molecular analysis of Yellow rust of Wheat

Abstract

India is, the world's second-biggest producer of wheat. Wheat stripe (yellow) rust, caused by Puccinia striiformis f. sp. trilici (Pst), is the most important foliar disease on wheat. The rust disease of wheat are among the most studied fungus. The leaves samples collection were made from crop research center, chirori farm anq rest of the experiments were conducted at Plant Health Clinic of Department of Plant Pathology, S.V.P. University of Agriculture & Technology, Meerut (U.P.) . . The identification of pathogen in infected plants based on morphological .m.p...hy.si_Ql_ogic.al· criteria before.spor.ulatien is labourintensive and time-consuming. The symptomatology of all above-ground parts of wheat plants showed stripe rust symptoms and rust infected wheat leaves exhibited the appearance of yellow-colored stripes produced parallel along the venations of each leaf blade. The morphological observations on leaves symptoms were recorded and identified as small orange-yellow colour pustules forming in vertical lines on wheat leaves. The various leaves samples were analyzed for the visual observation under laboratory conditions. The glass slides of rust pathogen were prepared using lectophenol for microscopic studies and then microphotographs was captured. Stripe rust spores are yellow to orange in colour. The treatments were designed to findout the amplification of fungal DNA extracted from infected wheat leaves showing yellow rust symptoms (pustules) as well as non-symptomatic samples collected from the same field using RAPD markers to assessment of genetic variations. · Results indicates maximum amplification was observed in at lane no 20 primers produced 4 bands followed. py 1three bands were produced by each in primers of lane no 3, 14,15 and 21. While, primers in lane 4!5,9, 10,'12,17, and 18 did not amplified any of DNA samples. A dendrogram was generated using RAPD amplification data and used to analyzed by unique combinations of DNA of yellow rust infected wheat leaves samples. Three clusters were observed which shown variations ranges from 0.09 to 0.75% coefficient. however, K-910 (sporulated) have shown 0.75 per cent coefficient value, which indicates the K-910 genotype was infected by two different pathotypes of the same fungus. The results also indicate that latent infection except Raj3765 (sporulated) and sporulated leaves samples have genetic variations among the yellow rust pathogen within the same locality of wheat growing fields. To accelerate and simplify the process of detection, a polymerase chain reaction (PCR) based assay was tried for specific and sensitive detection of Puccinia striiformis f. sp. tritici (Pst). The ITS3 and ITS4 Primers were designed according to a (White et a/. I 990) for this purpose. Using extracted DNA from stripe rust-infected wheat leaves, the fungus will be detennined within the infected leaves before symptom appearance. The PCR assay provides a rapid and sensitive method for detection of P. striiformis f. sp. tritici in latently infected (non-symptomatic) leaves of wheat plants. Specificity of the primers was tested in the PCR assays using DNA extracted from all collected P. sh·iiformis f. sp. h·itici infected leaves along with healthy leaves. our results indicates that only the DNA extracted from the leaves (symptomatic and non-symptomatic, both) collected from field was amplified and it was not true in case of DNA extracted from healthy wheat leaves. The molecular diagnosis and detection of stripe rust will provide a useful aid to the accurate forecast and seasonal control of!IJ.is-destructive disease~lt is concluded that are molecular diagnosis and detection are strip rust will be useful and can be used to the accurate forecast during wheat season to control yellow rust diseases using ITS markers and RAPD data shown that various DNA extracted from infected different wheat varieties have genetic variations among the yellow rust pathogen in infected wheat fields of the same locality.