Meta-QTL Analysis and Identification of Candidate Genes for Spot Blotch Resistance in Bread Wheat

Abstract

Abstract In bread wheat, a meta-QTL (MQTL) analysis was conducted using 275 QTLs that were available from 24 earlier studies and 275 QTLs were identified from all these studies of QTLs analysis. A dense consensus map comprising 73788 molecular markers. These 275 QTLs resulted 22 MQTLs, which were found on 15 of the 21 chromosomes (excluding 1D, 3D, 4A, 5D, 6B, and 6D). MQTLs Composite interval (CI) ranged from maximum 0.0 to maximum 422.9 cM. Furthermore, 11 MQTLs out of the 22 MQTLs affected more than one feature, demonstrating their pleiotropic nature. The following four MQTLs were significant among these 11 MQTLs: (1) MQTL14, MQTL15, MQTL21 and MQTL22 which were the major MQTL located on chromosome 5B and 7D with PVE 17.12% and 10.5% and mean PVE % for individual MQTLs ranged from 4.0–19% with their CI ranging from 0.0 cM (MQTL1) to 422.8 cM (MQTL22). Each MQTL exhibits a unique set of features such as stay green, wheat flag leaf senescence, green leaf area duration, green leaf area of main stem, and all the above resistance to spot blotch. MQTL2, MQTL3, MQTL10, and MQTL13 were shown to have a variety of features at one locus, demonstrating a close relationship between these characters. In present study, we found two major spot blotch resistance genes, Sb1 and Sb2, with QTLs shown Qsb.bhu-5B, Qsb.pau-5B, Qsb.bhu-7D, QTs-7D, and QTs-7D. We had also found other QTLs those were associated with spot blotch resistance. These QTLs were QGlnms20-5B, QSG.qgw-5B, QGlad25-5B, QTmrs-5B, and QTs-7D. Total 2509 unique CGs have been identified in the genomic areas of 22 MQTLs. These CGs encoded approximately 503 proteins in which the role of 412 protein have already been established in the resistance to several biotic stresses. The differential expression of candidate genes were measured on the basis of fold change value and found the maximum 5.4-fold change for positive regulation and − 5 FC value for the negative regulation. These genes were encoding proteins from the following classes: Proteins with a R domain, Transcription factors (Zn finger binding proteins, SANT/Myb domains, NAC domain, BTF3), Sugar phosphate transporter domain, Zinc finger C2H2-type, Protein kinase domain, DEP domain, NB-ARC, Leucine-rich repeat domain superfamily, AAA + ATPase domain.