Molecular Evaluation of Chemically Induced Male Sterility in Brassica Juncea (L.) Czern & Coss
PROCEEDINGS THE 12th INTERNATIONAL RAPESEED CONGRESS II Sustainable Development in Cruciferous Oilseed Crops Production Wuhan, China March 26-3U, 2007 Science Press
8 Pages Posted: 5 Feb 2008
Plants of Brassica juncea var. Pusa bold were sprayed with some chemical hybridizing agents (CHAs), namely, surf excel -a detergent; benzotriazole; ethrel and gibberellic acid. All the treatments induced significantly high extent of pollen sterility (94.6-100). Surf excel treated plants exhibited changes in floral morphology' which were used to promote out-crossing. Yield components were insignificantly different from control once in plants sprayed with lower concentrations of surf excel and benzotriazole. However, lower doses of ethrel and gibberellic acid brought about significant increase in yield as compare to control.
LM and TEM studies revealed that pollen abortion in CHA treated plants was associated with abnormal behavior of tapetum, endothecium and pollen grains. Development of endothecium was inhibited in sterile anthers. This was associated with malformed tapetum supporting programmed control of tapetum on endothecial development. The cells in tapetum failed to degenerate and remained intact, however, sometimes they elongated radially or form pseudoperiplasmodium. Ultrastructural studies revealed the presence of increased number of mitochondria and enlarged degenerated plastids in the tapetal cells in the anthers of surf excel treated plants. On the other hand, tapetum in benzotriazole and ethrel treated plants exhibited pre-mature degeneration of mitochondria and plastids. Secretion of higher quantity of sporopollenin was recorded in the tapetal cells of anthers of benzotriazole treated plants as marked by their accumulation at several places in anther locule. Pollen grains of the treated plants consisted of degenerated protoplast. The intine in sterile pollen grains was lacking while the exine was abnormally thick but poorly differentiated into tectum and baculae.
The molecular studies based on RAPD, Dot-blot and RT-PCR analysed two fertility related anther specific genes i.e. Bcpl aid callase. These experiments indicated that there was a transitional change in the intensity of bands. Both the genes were present in anthers of CHAs treated plants. However, their activity was either suppressed or over expressed. Since tapetal mitochondria exhibited abnormal behaviour, analysis of mt-DNA has also been initiated.
Keywords: : Brassica juncea, chemical hybridizing agents, pollen sterility, anther development, gene expression
JEL Classification: A00
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