Germination-induced Changes in Chromosomal Proteins of Spring and Winter Wheat Embryos

Abstract

The template activity of chromatin from winter wheat embryos gradually increased during germination and was regulated with some nonhistone proteins different from the two major ones, molecular weight 39k and 59k polypeptides, previously reported.To clarify chromosomal proteins which are involved in regulation of template activity of chromatin, we studied the quantitative and qualitative changes in chromosomal proteins. Differences In wheat embryos the activities to synthesize mRNA, rRNA, and tRNA were observed to be activated and increased during germination (8,9,11,25,29, 34 (35) reported that the template activity of chromatin with exogenous DNA-dependent RNA polymerase II from wheat embryo was constantly very low for the first 18 h of germination, thereafter increased 2-fold and 5-fold at 24 h and 60 h of germination, respectively, in parallel with the decrease in the amounts of two major nonhistone proteins, mol wt 39k and 59k polypeptides. We have recently demonstrated that some nonhistone proteins, different from 39k and 59k polypeptides, which originated from germ chromatin having very low template activity, inhibited transcriptional activity; whereas those which originated from seedlings having high template activity stimulated transcriptional activity in reconstituted chromatin (36). This describes further quantitative and qualitative changes in chromosomal histone and nonhistone proteins, that may be involved in changes of template activity of chromatin.Similarities and diversities of chromosomal nonhistone proteins and histones between spring and winter wheat embryos are also noted. MATERIALS AND METHODSWheat Seeds and Germ. Wheat germ (spring and unknown variety) was purchased from Nippon Seifun Corporation and stored in a cold room at 4 C.Seeds of wheat, Triticum aestivum L. cv. Mukakomugi (winter wheat, 1977) and cv. Haruminori (spring wheat, 1976) were supplied by the Kitami Branch of the Hokkaido Agricultural Experiment Station. The seeds were sterilized with 0.05% (w/v) HgC12 solution for 15 min, washed in tap water for 30 min, transferred to Petri dishes, and grown in the dark at 24 C. After a desired period, the radicle-omitted embryos were separated by hand from the endosperms.Preparation of Chromatin. Chromatins were prepared from germ and germinated embryos by a slight modification of the method of Simon and Becker (27). Sample of germ or embryos was homogenized by a VirTis "45" homogenizer in grinding buffer containing 0.05 M Tris-HCl (pH 8.1), 0.5% (w/v) Triton X-100, and 0.1 mm phenylmethylsulfonyl fluoride. The homogenate of embryos was filtered through four sheets of gauze, while that of germ was stirred for 10 min, and was followed by centrifugation at 2,600g for 5 min. The resulting supernatant was filtered through two layers of Miracloth, made as 0.05 M (NH4)2SO4 solution, and centrifuged at 10,000g for 10 min. The pellet of chromatin obtained was resuspended in a Potter-Elvehjem homogenizer with a Teflon pestle in grinding buffer containing 0.05 M (NH4)2SO4, centrifuged,...

Histone variants and high mobility group non‐histone chromosomal proteins of higher plants: Their potential for forming a chromatin structure that is either poised for transcription or transcriptionally inert

“…Nicklisch et al (1976) reported changes in HI variants in different regions of corn root tips, and Faulde and NagI (1987) have reported cultivar, organ and herbicide treatment-specific variation of histone HI in maize. Sugita et al (1979) presented data indicating that the HI variant. Hid, is slightly reduced 48 h after germination of wheat embryos.…”

Arabidopsis thaliana H1 histones

“…As has been found in animal systems, the relative amount of an HI subtype can vary during plant development. For example, Sugita et al (1979) reported a decrease in the relative amount of variant Hld upon germination of wheat embryos.…”

Arabidopsis thaliana H1 histones

“…For example, mammals typically have at least seven electrophoretically distinct HI histone subtypes; each of which is encoded by a separate gene. For example, Sugita et al (1979) reported a decrease in the relative amount of variant Hld upon germination of wheat embryos. As has been found in animal systems, the relative amount of an HI subtype can vary during plant development.…”