Showing papers on "Nigella damascena published in 1978"

Integumentary studies in the polycarpicae v. nigella damascena l.

Abstract: SUMMARY The ovule primordium of Nigella damascena is three-zonate. The nucellus of most ovules is crassinucellate. The inner integument is of dermal origin, whereas the outer integument is initiated subdermally. These ovule characteristics correspond with those of the supposedly most original type of the angiospermous ovule. The ovule can be used as a base of comparison with unitegmic ranunculaceous ovules and with ovules showing a structure intermediate between bi- and unitegmy.

Differential Effects of Kinetin on Acidic Ethyl Acetate-soluble and Highly Water-soluble Gibberellin Fractions in ‘Single’ and ‘Double’ Nigella damascena L.

Abstract: The extractable GA-like substances from seedlings of both 'double' and 'single' genotypes of Nigella damascena are equally compartmentalized between AES and HWS fractions. However, when seedlings were floated on an aqueous solution of kinetin prior to extraction, the compart mentalization profiles were altered differentially. The levels of the AES fraction from 'double' tissues increased concomitantly with a decrease in the level of the HWS fraction. No detectable shift in the activity of AES and HWS fractions was observed in 'single' seedlings. This differential response to kinetin parallels other observations on these two genotypes and substantiates an interpretation that these two morphologic traits are associated with rather different capacities to metabolize GAs. INTRODUCTION Studies of the hormonal relationships in the different expressions of two flower mutants ('double' and 'single') of Nigella damascena reveal strong correlations between GAs, both endogenous levels and compartmentalization patterns, and a number of morphological and physiological responses to applied GAs (Raman, 1976; Raman and Greyson, 1977a, b). For example, in the presence of GAs,'single' buds failed to initiate nectaries and stamens, but produced only sepals and carpels if cultured at the pre-sepal stage. However, these 'single' flower buds produced all classes of organs when cultured on a basal medium devoid of any plant growth regulators and growth was enhanced by the addition of IAA or kinetin. 'Double' buds failed to initiate organs when reared on a basal medium or one supplemented with IAA, however, gibberellic acid (GA3) or kinetin promoted the initiation of all organ types and their subsequent development (Greyson and Raman, 1975). Further, 'double' flower buds contained more GA-like substances than did 'single' buds. In addition, the bulk of the GA-like substances of the 'single' genotype was in a highly water-soluble (HWS) form, whereas 'double' flower buds contained essentially only acidic ethyl acetate-soluble (AES) acids (Raman and Greyson, 19776). On the basis of these observations we have hypothesized that one Abbreviations: AES = acidic ethyl acetate-soluble; HWS = highly water-soluble; GA = gibberellic acid; IAA = indoleacetic acid. This content downloaded from 207.46.13.128 on Wed, 07 Sep 2016 06:32:15 UTC All use subject to http://about.jstor.org/terms 142 Raman and Grey son—Effects of Kinetin on Gibberellin in Nigella biochemical difference between these two genotypes could involve their differential abilities to interconvert GA-like substances between the AES and HWS fractions. Because flower buds of both genotypes can be successfully cultured on a medium containing kinetin in the absence of GAs, as well as reports which indicate that cytokinins can play a crucial role in altering the levels of GAs in certain higher plants (Sebânek, 1966; Karanov and Vassilev, 1969; Chin and Beevers, 1970; Reid and Railton, 1974a,*6), we studied the differential responses of the two genotypes to applied kinetin. In this report, we present some observations on the effect of kinetin application to the compartmentalization of GAs in seedlings. MATERIALS AND METHODS Seedlings were used for this study because of the presence of both HWS and AES forms of GA-like substances in detectable quantities at this stage of development in both genotypes (Raman, 1976). The isolation, selection, and growing conditions of these two genotypes were previously described (Raman and Greyson, 19776). Seedlings with fully grown cotyledons but no visible leaves were washed free of all soil particles and then floated in 0-02% Tween-20 in glass-distilled water containing 10~5 M kinetin for 10 h in the dark at room temperature. Seedlings, floated in 0-02% Tween-20, served as controls. After 10 h the seedlings were washed again in glass-distilled water, blotted between paper towels, weighed, immersed in liquid nitrogen, and lyophilized. The extraction, purification, and bioassay of HWS and AES GA-like substances were performed as described previously (Raman and Greyson, 19776). The experiment was repeated once with results similar to those presented below. RESULTS AND DISCUSSION Estimates of the extractable GA-like substances in 'single' and 'double' seedlings from lettuce hypocotyl assays are presented in Figs 1 and 2. GA-like activity in this assay showed two broad peaks (RF 0-0-0-3 and 0-4-0-8) in the case of the AES fraction (Fig. 1a) and three zones of activity, RF 0-0-0-1, 0-2-0-6, and 0-7-0-9, in the case of HWS fraction (Fig. 1b) of'singles' (30 g fr. wt. equivalent). However, untreated 'double' tissues (10 g fr. wt. equivalent) showed higher levels of GA-like substances. In the extracts of the control 'double' tissues, the main GA-like activity of the AES fraction was spread throughout the chromatogram, although the highest activities were concentrated at RF 0-2-0-5 and 0-6-0-8 (Fig. 2a). HWS GAs of these seedlings showed two zones of activity, RF 0-0-0-6 and 0-8-0-9 (Fig. 2b). These chromatograms are comparable to those from similar tissues described previously (Raman and Greyson, 19776). The influence of kinetin on the endogenous levels of GA-like substances in the seedling tissues of these two genotypes is shown in these same figures (Figs lc,D, 2c,d). While the chromatograms of the control and kinetin-treated seedlings of the 'single' genotype display some variability, there is little evidence that kinetin affected the extractable level of HWS or AES GA-like substances in these tissues (Fig. 1a). However, results from the same assays of'double' seedling extracts are quite different. Treatment with kinetin altered both the levels as well as the distribution of GAs between the AES and HWS fractions (Fig. 2c,d). In the AES fraction, the activity was distributed in all the RFs except the last. All other RF zones showed higher activity than those from untreated control extracts. However, activity in the HWS fraction decreased significantly, with only traces of activity This content downloaded from 207.46.13.128 on Wed, 07 Sep 2016 06:32:15 UTC All use subject to http://about.jstor.org/terms Raman and Greyson—Effects of Kinetin on Gibberellin in Nigella 143 GAjCug)