Spot blotch (SB) disease caused by the hemibiotrophic pathogen Bipolaris sorokiniana inflicting major losses to the wheat grown in warm and highly humid areas of the Indian subcontinent, including Bangladesh, necessitates identification of QTLs stably expressing in Indian subcontinent conditions. Thus, two RIL mapping populations, i.e., WC (WUYA × CIANO T79) and KC (KATH × CIANO T79), were phenotyped at Dinajpur, Bangladesh for three consecutive years (2013-2015) and genotyped on a DArTseq genotyping by sequencing (GBS) platform at CIMMYT, Mexico. In both populations, quantitative inheritance along with transgressive segregation for SB resistance was identified. The identified QTLs were mostly minor and were detected on 10 chromosomes, i.e., 1A, 1B, 2A, 2B, 2D, 4B, 4D, 5A, 5D, and 7B. The phenotypic variation explained by the identified QTLs ranged from 2.3–15.0%, whereby QTLs on 4B (13.7%) and 5D (15.0%) were the largest in effect. The identified QTLs upon stacking showed an additive effect in lowering the SB score in both populations. The probable presence of newly identified Sb4 and durable resistance gene Lr46 in the identified QTL regions indicates the importance of these genes in breeding for SB resistance in Bangladesh and the whole of South Asia.

Symptoms of partially bleached and completely white heads were observed in a triticale (× Triticosecale) cultivar ‘BARI Triticale 1ʹ in the research plots at the Regional Agricultural Research Station, Jashore, Bangladesh, during April 2019. Foliar symptoms with elliptical or eye-shaped lesions were also found on plant leaves. The main intention of this study was to isolate and identify the causal organism of the disease. Morphological characteristics of the pathogen showed the presence of pyriform 2-septate hyaline conidia and coloured conidiophores, indicating the presence of the fungus Magnaporthe oryzae. Molecular analyses by ITS sequence analysis and amplification of the product with MoT3 primers confirmed the identity of the fungus as M. oryzae pathotype Triticum. The pathogenicity of the representative isolates was confirmed by inoculation of triticale heads and leaves under laboratory conditions, resulting in similar symptoms as observed in the field. To our knowledge, this is the first report of triticale blast caused by M. oryzae pathotype Triticum in Bangladesh.