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20141
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Subject: Molecular Biology and Biotechnology × Author: Aneja, Bharti × Start date: 1999 × Type: Thesis × Thesis Type: Ph.D ×
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    ThesisItemOpen Access
    Transcript profiling of stress inducible MYB transcription factor and related genes in Indian mustard (Brassica juncea L. Czern. & Coss.)
    (CCSHAU, 2014) Aneja, Bharti; Yadav, Neelam R.
    Drought stress reduces the capacity of plants to take up water from soil, limiting plant growth and yield worldwide. The present investigation was carried out to study the expression of drought stress induced myb transcription factor genes (myb2, myb44, myb60) and related genes (hsp, pp2c and lhcb) in Brassica juncea cvs. RH0116 (drought tolerant) and RH8812 (drought sensitive) through semi-quantitative RT-PCR using actin gene as control. Brassica plants were raised in nethouse and subjected to drought stress by water withholding at flowering stage. We found that myb2, myb44, hsp and pp2c genes were upregulated and were expressed in both shoots and roots during drought stress. RH0116 showed higher accumulation of myb2, myb44 and pp2c transcripts as compared to RH8812. Whereas, myb60 and lhcb genes were downregulated during drought stress and their expression was limited only to shoots. The drought stress induced Atmyb44 homologues from RH8812 and RH0116 were cloned, sequenced and designated as BjMyb44-1 (872 bp) and BjMyb44-2 (862 bp) respectively. These had much similarity to other myb genes of Arabidopsis thaliana (84%) and Brassica rapa (94%). Multiple sequence alignment using CLUSTALW2 program with each other and with other sequences established homology. Seeds of both the genotypes were grown on MS medium with various levels of stress treatments using PEG 6000, Mannitol and ABA. Seed germination was arrested at initial stage only and reduction in seed germination was significant among treatments and no seedling growth was observed in case of ABA treatment. The average shoot and root lengths of seedlings decreased with the increasing dose of PEG & Mannitol in both the genotypes. The Brassica plants grown in vivo and two weeks old in vitro grown Brassica seedlings subjected to air drying stress treatments were used to assess the physiological parameters. The stressed plants showed lower Relative water content as compared to the control plants and the decline was higher in sensitive check. Osmotic potential was found to be more negative in case of stressed plants than control plants and decrease was relatively more in RH8812 as compared to RH0116. Electrolyte leakage increased in stressed plants as compared to control plants and RH8812 showed more increase than RH0116. Chlorophyll fluorescence study revealed that the value of ratio of variable fluorescence to minimum fluorescence (Fv/ Fm) was more in the control plants as compared to stressed plants, however, the increase was relatively more in RH8812 than RH0116.