Genetic dissection of protein synthesis control in endosperm
--E. Rizzi, C. Balconi, D. Bosio, L. Nembrini, F. Salamini,* M. Motto and M. Maddaloni
With the aim of improving knowledge of protein synthesis control in endosperm and to define genic functions mediating the state of metabolism on transcriptional regulation of endosperm-specific genes, our collection of defective endosperm (de) mutants, introgressed into a B37 background, has been subjected to analyses. de endosperms, either grown in vivo or cultured on artificial media containing different levels of nitrogen (N), were fractionated for their protein content (zeins, albumins + globulins, glutelins and residue N). The data obtained indicate that differences exist between B37 and its deversion and between de mutants themselves (Fig. 1). A similar result was reported by Manzocchi et al. (Maydica 35:199, 1980), although some differences exist between the data reported in the cited paper and ours. Such discrepancies may reflect the different analytical methodologies adopted and/or the environmental variabilities among years. In order to standardize the conditions for growth and to evaluate the response of de mutants to different N nutrition, endosperms of B37+ and its de versions were grown in vitro on media containing different levels of N (media 1 and 3 as described in Balconi et al., The Plant Journal 3:325, 1991). Here we report the data only for B37, B37 de*-246, and B37 de*-22. As can be seen in the graphical representations, differences can be seen relative to the utilization of organic and inorganic N for the protein synthesis. At present we also have data indicating that, in addition to quantitative differences, the presence of qualitative differences are detected in zein and in albumin plus globulin fractions. Studies are in progress to define variations of starch and soluble sugars at quantitative and qualitative levels.
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