Effects of 28-homobrassinolide on growth, lipid peroxidation and antioxidative enzyme activities in seedlings of Zea mays L. under salinity stress

The effects of 28-homobrassinolide (28-homoBL) on seedling growth, lipid peroxidation and antioxidative enzyme activities in the seedlings of Zea mays L. (var. Partap-1) under salt (NaCl) stress were studied. The surface-sterilized seeds were germinated in petriplates containing different concentrations of NaCl (25, 50, 75 and 100 mM) only, 28-homoBL (10⁻⁷, 10⁻⁹ and 10⁻¹¹ M) only and NaCl supplemented with 28-homoBL for 7 days. The activities of superoxide dismutase (SOD, EC 1.15.1.1), guaiacol peroxidase (POD, EC 1.11.1.7), catalase (CAT, EC 1.11.1.6), ascorbate peroxidase (APOX, EC 1.11.1.11) and glutathione reductase (EC 1.6.4.2) were analysed in 7 day-old seedlings. It was observed that 28-homoBL treatments reduced the toxicity of salt on seedling growth considerably. Lipid peroxidation level was significantly increased under saline stress, but lowered with 28-homoBL applications revealing less oxidative damage. Further 28-homoBL treatments to the seedlings showed an enhancement in activities of SOD, POD, CAT and APOX. The activities of all antioxidative enzymes were further increased in seedlings treated with solution containing 28-homoBL and salt together as compared to seedlings treated with different concentration of salt solution only.     

Recalcitrant Grain Legume Vigna radiata, Mung Bean, Made to Regenerate on Change of Hormonal and Cultural Conditions

Induction of shoots is possible from cotyledonary node of Vigna radiata seedlings by culturing them on a low concentration of thidiazuron (TDZ 1.0 μM). Interestingly, flooding the seedlings with the same concentration of TDZ considerably enhanced this effect and also led to the induction of shoots from the epicotyl – an unexpected and significant finding. Even plain mineral medium evoked this response on flooding. But seedlings raised on TDZ and flooding with mineral medium was not so effective. Instead seedlings raised on TDZ (1.0 μM) medium as well as flooding with it had synergistic effect. In a comparative study TDZ (1.0 μM) was found to be more effective than BAP (10 μM). Marked repression of root formation and expansion of shoot–apex were noted in seedlings raised on TDZ or BAP, particularly in cultures that were flooded.     

Significance of the gonoduct in the classification of echiurans (Phylum Echiura)

The gonoducts of 21 species have been studies. The reliability of the gonoduct as a taxonomic tool has been assessed at different levels of the hierarchy, employing the variations in respect of the number of genital pores, and the modifications in the body of the females for lodging the males in the case of sexually dimorphic echiurans. Special reference has been made to sexually dimorphic echiurans and their position in the taxonomy of the phylum.     

Sequence Analysis of a Plastidial Omega-3 Desaturase Gene from Brassica juncea

A genomic clone (λg₂) encoding a plastidial omega-3 desaturase has been isolated from a genomic library of Brassica juncea cv Pusa Bold and sequenced after subcloning. A continuous stretch of 3866 by of the clone sequenced showed homology with omega-3 desaturase from other plant sources but maximum homology was with that of a plastidial omega-3 fad 7 gene. This sequence designated as Bjgfad7 includes 1381 by 5’ untranslated region, 273 by 3’ untranslated region along with an open reading frame of 1290 by interrupted by 7 introns. The 5’ untranslated region contains putative cis elements responsible for seed specificity, light responsive and stress-inducible expression besides minimal promoter elements.