Identification of maize genotypes tolerant to waterlogging and their characterization using rice orthologs
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Date
2021
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Punjab Agricultural University, Ludhiana
Abstract
Waterlogging, second most important abiotic constraint after drought, leads to around 25-30% of production losses each year. Identification of suitable donor lines with tolerance against waterlogging and their genetic and morphological characterization is essential to develop varieties that can overcome the ill effects posed by excess soil moisture. The present study focused on identification of maize genotypes tolerant to waterlogging and their characterization using rice orthologs. A set of 119 different genotypes belonging to different heterotic pools along with Zea mays spp parviglumis were screened at pre-emergence and seedling stage (V2) against different duration of waterlogging. In response to waterlogging all morphological parameters showed significant decline over increased duration of waterlogging. Based on selection indices, multi trait stability index (MTSI) and survival data after nine days of waterlogging, lines selected for tolerance against waterlogging are EML 153, SE 503, EML 125, AVL13119, VL 1010764, I 168, I 204, AVL13056, PML 368, LM 17, Z. mays spp parviglumis, PML 373, PML 387, EML 285, JCY 20, I 170, I 185, I 172, PML 1228, PML 243, PML 28, EML 124, LM 6, I 185 and I 192.Waterlogging tolerance coefficient (WTC) for tolerant lines lies near or above one. Broadened anthesis silking interval (>5 days) was recorded for susceptible lines, while for tolerant lines it lie within the normal range of 3-5 days. Search for ortholog genes responsible for submergence tolerance in rice revealed no significant region for SNORKEL, but significant sequence similarity for two out of three coding sequences for Sub1A. Synthesis of gene specific primers and allelic survey study showed no significant allelic variation for these genes in studied genotypes. Gene expression study revealed significantly higher fold expression of these genes in tolerant lines (up to 15 folds) during early stage of waterlogging (3 days of waterlogging) suggesting their involvement in conferring tolerance against anaerobic growth condition. Population structure analysis revealed presence of three sub-populations in our available germplasm. An average Polymorphism Information Content (PIC) value of 0.503 was obtained for SSR markers used for the genetic diversity study. Marker Trait Association (MTA) revealed two markers umc-1021 and umc-2340 to be significantly associated with both root area (-log10p of 3.91) and root volume (-log10p of 11.34).
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Thapa, Sittal (2021). Identification of maize genotypes tolerant to waterlogging and their characterization using rice orthologs (Unpublished M.Sc. thesis). Punjab Agricultural University, Ludhiana, Punjab, India.