Singh, N.K.Joshi, Anjali2021-10-292021-10-292021-01https://krishikosh.egranth.ac.in/handle/1/5810177519The investigation was undertaken with the objective to map genomic regions governing morphological traits and resistance to Maydis leaf blight and red flour beetle. The field experiments pertaining to development of BC1F5 mapping population were conducted during kharif 2017 and rabi 2017-18. While phenotyping of mapping population for morphological traits and MLB disease resistance was conducted during Kharif 2018. The BC1F5 lines were phenotyped for red flour beetle resistance in Kharif 2018 under laboratory conditions. Analysis of variance revealed highly significant variation amongst the evaluated BC1F5 lines for MLB resistance under both E2 and E4. Under E2, 26, 77, 51 and 15 lines were categorised as susceptible, moderately susceptible, moderately resistant and resistant. While under E4, 64, 91, 10 and 4 lines were grouped as susceptible, moderately susceptible, moderately resistant and resistant, respectively. Seven lines (MT-26, MT-95, MT-148, MT-190, MT-195, MT-73 and MT-115) belonged to resistant category in both the environments. Significant differences amongst the evaluated lines were detected for all the morphological traits in all four environments as revealed by ANOVA. There was presence of significant variance between E1 and E2 for days to 50 per cent anthesis, days to 50 per cent silking, flag leaf length, plant height, ears per plant, node bearing first ear, ear length, ear diameter, kernel rows per ear, kernels per row and grain yield per plant. For E3:E4, significant differences were identified for days to anthesis, days to silking, flag leaf width, ear per plant, kernel rows per ear, kernels per row and grain yield per plant. Presence of significant differences indicates substantial impact of disease stress on these characters. Significant negative correlation was observed between MLB disease score and days to 50 per cent silking, plant height, ear length, ear diameter, kernel rows per ear, kernels per row, test weight and grain yield per plant in E2. While in E4, significant negative correlations of MLB disease score with plant height, ear length, kernels per row and grain yield per plant were noted. Single marker analysis method facilitated identification of 6 and 5 MLB resistance QTLs in E2 and E4, respectively. The disease resistance QTLs identified in E2 consisted of two major QTLs and four minor QTLs located on chromosome 2, 4 and 7. In E4 one major and four minor QTLs conferring disease resistance were found on chromosome 3 and 7. Two QTLs linked with marker umc2392 and umc1393 were detected in both E2 and E4 and were stable. A total of 203 QTLs (9 major and 194 minor) for fourteen morphological traits in four different environments were also identified on all ten maize chromosome. Maximum number of QTLs were noted on chromosome 2 (45 QTLs) followed by chromosome 1 (33 QTLs) and chromosome 4 (25 QTLs) in all four environments. Further, a total of 19, 19, 14, 14, 12, 12 and 10 QTLs were localised on chromosome 3, 10, 6, 7, 5,8 and 9, respectively. A total of 20 QTLs were detected in more than one environment with 13, 5 and 2 QTLs being spotted consistently in two, three and four environments, respectively. All of the eleven MLB resistance QTLs colocalized with twenty-five QTLs affecting eleven morphological traits in maize including days to anthesis, flag leaf length, flag leaf width, plant height, ear per plant, node bearing first ear, ear length, ear diameter, kernel rows per ear, kernels per row and grain yield per plant. Maximum number of four disease resistance co-located QTLs were found with flag leaf width, node bearing first ear and ear length. The BILs when assessed for red flour beetle resistance showed significant differences for four flour beetle resistance parameters namely, grain weight loss (WL), number of insect progeny (NIP), kernel damage (KD) and flour produced (FP). No positive transgressive segregants were observed for all the four resistance parameters and CSI. Whereas, 7, 20, 9, 9 and 10 BILs showed inferior performance than maize line for WL, NIP, KD, FP and CSI, respectively. Based on CSI, 24, 36, 33 and 50 inbred were categorised as highly susceptible, susceptible, resistant and highly resistant to red flour beetle damage. Highest phenotypic correlation was observed between NIP-FP (0.633) followed by WL-FP (0.571), KD-FP (0.398), WL-NIP (0.393) and NIP-KD (0.330). A total of 18 marker linked genomic regions on chromosomes 1, 2, 3, 4, 7, 8, 9 and 10 were found to be significantly associated with red flour beetle resistance in the BIL mapping population. Three QTLs each were localized on chromosome 1, 2, 4 and 10 while 2 QTLs each were marked on chromosome 3 and 8 whereas 1 QTL each was located on chromosome 7 and 9. QTLWL01, QTL KD02, QTL FP01 for WL, KD and FP, respectively, were linked to marker umc1024 and was colocalized. Umc1245 linked QTLNIP02 and QTL KD01 for NIP and KD, respectively co-localized on chromosome 1. Highest number of colocalized QTLs i.e., QTL KD02 and QTL FP01 (linked with umc1024), QTL KD03 and QTL FP02 (linked with bnlg197) and QTL KD06 and QTL FP04 (linked with umc1152) were observed for KD and FP. PCA showed five principal components which together explained 66.50% of the total phenotypic variation present in the data. Based on morphological diversity, at a Euclidean distance of 62.5, 171 genotypes including two parents were grouped into fourteen clusters. The maximum distance of 366.88 was observed between teosinte and inbred line MT-11 Mantel test revealed significant positive correlation of 0.499 between morphological and molecular marker information. The presence of significant correlations indicates that these two independent sets of data likely reflect the same pattern of genetic diversity and both of them should be utilized simultaneously and in conjugation to capture actual genetic diversity present in maize germplasm.EnglishThesis