Wheat leaf bases cultured for 1 day on 2,4-D (10 lM) display the induction of somatic embryogenesis. The induction of somatic embryogenesis by 2,4-D appears to be calcium-mediated as treatment of leaf bases with the calcium chelator, EGTA, prior to 2,4-D treatment, inhibited the induction of somatic embryogenesis. This sensitivity of auxin to reduced calcium levels can be reversed by calcium ions alone and not any other divalent cation like magnesium or zinc. Additionally, the expression of the three calciumregulated genes, Triticum aestivum calmodulin binding protein kinase, calcium-dependent protein kinase, and putative calcium binding protein was analyzed in wheat leaf bases which suggest a specific role for Ca 2+ in somatic embryogenesis. Application of the calcium ionophore, A23187, either alone or along with 2,4-D, induced somatic embryogenesis. This specificity for calcium was verified both by treatment with the calcium antagonist TMB8, and the elimination of calcium from the medium, resulting in reduction of somatic embryogenesis by 80%. Treatment with calcium channel blockers like verapamil and nifedipine, calcium antagonist, lanthanum, and calmodulin inhibitors chlorpromazine and fluphenazine, prior to the 2,4-D treatment, inhibited induction of somatic embryogenesis. The present study thus provides evidence for the involvement of calcium-calmodulin in the stimulus-response coupling of auxin-induced somatic embryogenesis in wheat leaf base system.

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Exogenous DNA uptake and transient expression of the GUS reporter gene was studied in wheat (Triticum aestivum L.) zygotic embryos employing a simple procedure of cellular permeabilization by membrane interactive agents like saponin and toluene. Uptake of expression vectors with different promoters was detected in mature and immature embryos. The frequency of GUS expression was detected to be higher in mature embryos than immature embryos probably due to a certain degree of disorganization of the plasmalemma during the dehydrated state of the embryos. Of the various permeabilizing agents employed, saponin and toluene were detected as potential membrane permeabilizers without adversely affecting embryo viability. Variations in GUS gene expression were not significant among different genotypes of T aestivum CPAN1676, PBW343 and HD2329, thus indicative of the relative genotype independence of this process. The results support the proposed idea of direct DNA uptake as an alternate and simple method for inserting foreign DNA into plant cells and its use for transformation of higher plants.

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Reciprocal cross differences in a 6 x 6 diallel set of groundnut (Arachis hypogaea L.) in the F 1 generation Summary Reciprocal cross differences were studied in a 6 x 6 diallel full set comprising of thirty hybrid combinations of groundnut in the F, generation .Reciprocal cross differences were observed for growth habit in four pairs of crosses, for leaf colour, flower colour and stem pigmentation in two pairs of crosses each . It was observed that the inheritance of flower colour, stem pigmentation and testa colour which exhibited different shades of purple colour was likely to be governed by pleiotropic gene(s) . Among the quantitative characters significantly positive reciprocal effects were observed in different crosses for number of mature pods per plant, weight of pods per plant and shelling percent . Marked reciprocal cross differences were observed for pod and kernel characters like pod filling, pod beak, pod constriction and testa colour .