Authors:M. Osman, X. He, F. Capettini, J. Helm and P.K. Singh
Fungal diseases pose a great challenge to Canadian barley production, among which are Fusarium head blight (FHB), yellow rust and scald. An integrated management approach is needed to mitigate these diseases, in which breeding for host resistance is the most effective component. Constant evaluation of advanced breeding lines for their resistance to the diseases is important for making steady progression. The main objective of this study was to screen 1,174 barley accessions, from a collaborative project between the Field Crop Development Center (FCDC), Alberta, Canada, and the International Maize and Wheat Improvement Center (CIMMYT), Mexico for their reactions to the three diseases. For FHB a 1-5 scale was employed to discard the very susceptible material in 2012 and 2013. In 2014, 514 most resistant lines having the score 1 in 2013 were re-evaluated in a replicated experiment. The most promising 166 genotypes were selected and advanced for their last evaluation in 2015 where FHB index was measured. Simultaneously, these 166 genotypes were subjected to two more experiments to test their reactions against stripe rust and scald. Eighteen two-rowed barley genotypes exhibiting broad-spectrum resistance to all of the three evaluated diseases were identified in addition to 40 lines combining FHB resistance with resistance to Mexican isolates and natural fungal population of either of the two foliar diseases and could be utilized in breeding programs aimed at improving resistance to multiple barley leaf and head blight diseases.
Authors:M. Sivasamy, M. Aparna, J. Kumar, P. Jayaprakash, V. Vikas, P. John, R. Nisha, Satyaprakash, K. Sivan and E. Punniakotti
Nearly twenty thousand wheat lines were phenotyped for the presence of leaf tip necrosis (LTN), a phenotypic trait linked to adult plant leaf rust resistance (APR) genes, viz. Lr34, Lr46 and Lr67 having pleiotropic association with multiple disease resistance genes. Thirty-six lines showed varied expression of LTN and moderate level of leaf rust severity at adult plant stage with slow rusting (disease progress at a retarded rate). Seedling resistance test (SRT) revealed susceptible and mixed infection types, a characteristic of adult plant resistance (APR) genes. Further molecular confirmation for the presence of these genes using available microsatellite markers revealed that of the 36 lines, five lines carried Lr46+ alone and five other lines carried Lr67+ alone. Seven lines carried the combination of Lr34+ and Lr67+ while six lines confirmed to carry the combination of Lr46+ and Lr67+. Remarkably three lines carried all the three APR genes, viz. Lr34+, Lr46+ and Lr67+. All these stocks can be a source of APR multiple disease resistance genes. Ten lines were not confirmed to carry any of the genes but still had LTN and SRT results showing an infection type typical of APR genes and these can be the source of identifying newer APR genes. The resistance based on minor APR genes when combined with a few additional minor genes in the background of high yielding cultivars is expected to have high level of race non-specific resistance and to be durable.
Horizontal (field) resistance to late blight and common scab that is controlled by numerous genes proved to be quite durable in certain potato varieties in Hungarian trials. Although it is difficult to breed for this type of resistance, it has become the preferable strategy in today's breeding programmes, providing long-lasting and less vulnerable protection. Potato breeding in Hungary has produced some promising cultivars such as White Lady, Százszorszép and Rebeka with multiple disease resistance that may play an important role in the Integrated Pest Management (IPM) of near future.
Authors:B. Kumar, K.S. Hooda, R. Gogoi, V. Kumar, S. Kumar, A. Abhishek, P. Bhati, J.C. Sekhar, K.R. Yathish, V. Singh, A. Das, G. Mukri, E. Varghese, H. Kaur, V. Malik and O.P. Yadav
. , Holland , J.B. , McMullen , M.D. , Pratt , R.C. , Balint-Kurti , P.J.
2010 . Mapping resistance quantitative trait loci for three foliar diseases in a maize recombinant inbred line population-evidence for multiplediseaseresistance
Ogbonnaya, F.C., Imtiaz, M., Bariana, H.S., McLean, M., Shankar, M.M., Hollaway, G.J., Trethowan, R., Lagudah, E.S., van Ginkel, M. 2008. Mining synthetic hexaploids for multiplediseaseresistance to improve bread wheat. Aust. J. Agric. Res, 59 :421