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Researcher Atmaram, Awakale Pramod
Advisor Dalal, Monika
Source KrishiKosh-Indian National Agricultural Research System
Content type Text
Educational Degree Master of Science (M.Sc.)
File Format PDF
Language English
Subject Domain (in DDC) Natural sciences & mathematics ♦ Life sciences; biology
Subject Keyword Cloning and Expression Analysis of Brevis Radix (brx) Gene From Diploid Species of Wheat Exhibiting Better Root Traits Under Osmotic Stress ♦ Biotechnology and Molecular Biology
Abstract Soil moisture deficit is a major factor limiting yield stability of wheat. Maintenance of root growth during water deficit can significantly contribute to yield stability by enhancing the ability of plant to extract water and nutrients from deeper layers of soil. The diploid progenitors of wheat are potential gene source for various agronomic traits including drought stress tolerance. However, these species have not been explored for root traits. Therefore to characterize this untapped genetic resource, seedlings of nine accessions of diploid wheat species, three accessions each from T. monococcum (AA genome), Ae. speltoides (BB genome) and Ae. squarrosa (DD genome) were phenotyped for root growth under two levels of osmotic stress viz. osmotic potential -0.5 (S1) and -1.48 bars (S2) for 10 days. Data on primary and total root length and seminal root number were recorded. Significant genetic variability was observed for root traits among the accessions with different genomes. Two of T. monococcum accessions (A1-81 and A3-80) showed significantly higher total root length under control conditions. Inductive root growth was significantly higher in three of the T. monococcum accessions as compared to Ae. speltoids and Ae. squarrosa accessions under osmotic stress conditions. There was an inherent difference in seminal root number with T. monococcum accessions (A1-81 and A3- 80) having double the number of seminal roots as compared with Ae. speltoides and Ae. squarrosa accessions. Osmotic stress reduced the number of seminal roots in most of the accessions except in T. monococcum accession A1-81. Primary root length was considerably higher in T. monococcum accessions (A1-81 and A3-80). In Arabidopsis, BREVIS RADIX (BRX) gene was found to contribute to 80% of the phenotypic variation for root length. Hence, an ortholog of BRX gene was identified in wheat in this study. Real-time RT-PCR analysis was used to compare the expression levels of BRX in the roots of T. monococcum acc. A1-81 with that of Ae. speltoides acc. B3-86 and Ae. squarrosa acc. D1-125 under control and osmotic stress conditions. BRX expression was downregulated by osmotic stress in all accessions. T. monococcum acc. A1-81 maintained higher level expression as compared with other two accessions under stress conditions. The full length coding sequence of BRX (1191bp) was cloned and sequenced from T. monococcum acc. A1-81. Nucleotide sequence alignment of T. monococcum BRX (TmBRX) with hexaploid homeologous loci of TaBRX-6AL and TaBRX-6DL revealed 98.57 and 96.24 % identity, respectively. The protein sequence alignments of TmBRX with TuBRX, TaBRX-6AL and TaBRX-6DL revealed the conservation of all the BRX domains necessary for its function. In conclusion, the study led to the identification of T. monococcum accession A1-81 as the best performing accession for root traits under osmotic stress. The sequence variation observed between TmBRX and homeologous loci of TaBRX- 6AL and TaBRX-6DL can be confirmed and used for developing genome based allelic marker for BRX gene. The cloned TmBRX gene will be useful for detailed functional analysis of BRX in wheat.
Educational Use Research
Education Level UG and PG
Learning Resource Type Thesis
Size (in Bytes) 4.91 MB