| 000 | 05454nam a22002177a 4500 | ||
|---|---|---|---|
| 999 |
_c291833 _d291833 |
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| 082 |
_a634.9 _bASH/SC Ph.D |
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| 100 | _aAswath, M N | ||
| 245 | _aScreening and QTL mapping for drought tolerance among the plus trees of Tectona grandis L.f. | ||
| 260 |
_aVellanikkara _bDepartment of Forest Biology and Tree Improvement, College of Forestry _c2024 |
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| 300 | _a123,xxxvp | ||
| 502 | _aPhD | ||
| 520 | 3 | _aABSTRACT The present study investigated standardization of the Miniclonal propagation technique, assessing genetic diversity among accessions using ISSR markers, screening plus trees for drought stress and recovery, and discovering Single Nucleotide Polymorphisms (SNPs) through Genotyping by Sequencing in plus trees of Tectona grandis L. f. The study attempted to map the QTLs associated with drought tolerance, providing valuable insights into the genetic basis of this trait in teak. The effects of auxins on epicormic shoot production and rooting were evaluated to select the best hormone combination. The shoot production varied among the auxins and their concentrations. Indole-3-butyric acid (IBA) at 4000 mg L-1 showed optimal shoot production, enhancing rooting potential, with the highest rooting percentages observed at 49.19% for 4000 mg L-1 IBA and 41.71% for 3000 mg L-1 IBA. The cuttings treated with 1-Naphthaleneacetic acid (NAA) showed only 5.61 to 14.01% rooting, whereas a combination of IBA and NAA encouraged the callusing. The size of the cuttings affected the rooting potential, and the rooting percentage showed a significantly positive correlation with shoot diameter (r=0.89). Further, epicormic shoot and root production was observed to vary significantly among the accessions. Aravallikkavu (10.67) and Top slip-6 (8.33) exhibited the highest epicormic shoot numbers, while Nedumkayam-1 displayed minimal shoot production. Nellikutha-6 showed the highest rooting percentage (57.11%), contrasting with Nellikutha-2 (22.50%). Subsequently, ten accessions were successfully propagated for further investigations. Genomic DNA from ten accessions was extracted using the modified CTAB protocol, yielding DNA concentrations ranging from 166.7 to 269.4 ng μL-1, with OD260/280 values between 1.86 and 2.08. Amplified bands resulted in 212 observed alleles, of which 199 were polymorphic, demonstrating genetic diversity, while 13 were monomorphic. The Jaccard similarity coefficient between Topslip-6 and Topslip-10 was 0.361, suggesting their genetic similarity. Accessions 6, 4, 10, 8, and 7 displayed coefficients of 0.504, 0.476, 0.465, and 0.440, respectively, indicating close relationships. Morpho-physiological and biochemical responses of teak ramets to drought stress were evaluated, indicating varying tolerance levels among accessions. Based on morphological indicator (percent leaf retained), accessions Topslip-6, Topslip-10, and Shankaramthode-1 were classified as "Highly Tolerant," whereas Nellikutha-2 was "Highly Susceptible". Photosynthesis varied, with Topslip-6 maintaining the highest 2 m-2 s-1) and Nellikutha-2 exhibiting the lowest (1.200) under drought. Accessions displayed diverse responses under drought for Fv/Fm (0.819- Topslip-10 to 0.309-TC11) and chlorophyll content (1.573- Nedumkayam-1 to 4.342 - TC4). Maximum proline was produced by Topslip-6 -1), whereas -1 -1) produced minimal proline. Similarly, Accession 8 produced lower glycine content -1), and Topslip-10 exhibited -1. Cluster analysis revealed distinct groupings, with PCA aiding accession selection based on performance indices, categorizing teak accessions into Highly Susceptible (Nellikutha-2), Susceptible (Nedumkayam-2 and Nellikutha- 1), Moderately Tolerant (Topslip-6, TC4, Nedumkayam-1, and Shankaramthode-1), and Highly Tolerant (Topslip-10, TC11, and Topslip-6) categories. Genotyping based on Illumina-assembled genomic sequences for diverse accessions was carried out. Variant calling on ten genomes yielded 7,518,960 variants and filtered down to 3,665 SNPs. GWAS identified 19 significant SNPs linked to drought tolerance, supported by QQ and Manhattan plots. BLASTX and UniProt annotations unveiled genes associated with stress resistance, organ formation, and metabolic processes. QTLs on Chromosome_1 (BLH9, POX), Chromosome_4 (DXS, TKL), and Chromosome_11 (MFS, MIK2) were implicated in diverse physiological functions. BLH9 is implicated in plant organ and shoot formation, xylem development, morphogenesis, and meristem activity. DXS is involved in chlorophyll biosynthesis and terpenoid biosynthesis. MFS regulates stomatal closure, while MIK2 is associated with various cellular responses, including cellular and root activity. The study enhances understanding of the genetic basis of drought tolerance in teak, contributing valuable information for breeding programs and sustainable forest management. The multidisciplinary approach integrating physiological, biochemical, and genomic analyses offers a comprehensive framework for understanding and improving teak cultivation, ensuring sustainable production in the face of environmental challenges | |
| 650 | _aForest Biology | ||
| 650 | _aTree improvement | ||
| 650 | _aQTL mapping | ||
| 650 | _adrought tolerance | ||
| 650 | _aTectona grandis L.f. | ||
| 700 | _aSanthoshkumar, A V(Guide) | ||
| 856 | _uhttps://krishikosh.egranth.ac.in/handle/1/5810220778 | ||
| 942 |
_2ddc _cTH |
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