绿豆子叶脱分化过程核酸代谢的研究

本文研究了绿豆(Phaseolus raditus L.cv.D317—1)子叶切段在激素诱导下脱分化过程中DNA和RNA代谢的变化。子叶切段在附加1ppm激动素(KT)和4PPm萘乙酸(NAA)的Miller培养基上表现出较高的脱分化能力。DNA含量和RNA含量在离体培养的前7天增加约2倍,随后DNA含量维持不变,而RNA含量仍缓慢增加;利用同位素掺入法测定的DNA和RNA合成速率,在培养早期迅速增加,第5天时分别增加了2倍和4倍,随后虽有所降低,但仍处于较高水平;DNase和RNase(pH4.5,pH7.5)活性在培养早期有所降低,随后不断增强。这些结果表明,绿豆子叶切段的脱分化过程伴随着DNA和RNA代谢的加强,特别是合成作用,这可能是子叶脱分化的主要代谢特征之一。

STUDY ON THE METABOLISM OF DNA AND RNA IN DEDIFFERENTIATING MUNG BEAN COTYLEDONS

The synthesis and degradation of DNA and RNA were studied in the dedifferentiating segments of mung bean (Phaseolus radiatus L. cv. D317-1) cotyledons. The segments expressed a high capacity of dediffirentiation on miller medium containing 1 ppm KT and 4 ppm NAA. Under this condition, the contents of both DNA and RNA increased between day 1 and 7 in culture. Afterward, DNA contents remained basically unchanged, while RNA contents continued to increase slowly. The rates of synthesis of both DNA and RNA, as measured by H-labelled precursor incorporation, increased rapidly after subculture, then decreased after day 5. However, the synthesis rates of DNA and RNA on day 11 were still 2 and 3 times that of the initial levels, respectively. The activities of DNase and RNase at pH 4.5 and 7. 5 declined simultaneously after subculture, but enhanced continuously between day 5 and 11. These results suggest that the dedifferentiation of mung bean cotyledons is accompanied by the enhancement of DNA and RNA metabolism, especially the acceleration of DNA and RNA synthesis rates, which may be an important characteristic of metabolism in the dedifferentiation of mung bean cotyledons.