【摘要】 在正常条件下,烟草Hyp抗性变异系愈伤组织内的游离脯氨酸含量是其野生型的4倍多。这种积累游离脯氨酸的特性在愈伤组织的转代、再生及次生过程中均十分稳定。虽然其他多种氨基酸含量也有所改变,但变异系内游离脯氨酸的积累具有特异性。由于脯氨酸对Hyp抑制效应具有部分的逆转作用,所以游离脯氨酸的积累是变异系抗Hyp抑制作用的重要原因。然而,变异系内蛋白质组成中的脯氨酸并没有特异性地增加。在Hyp存在条件下,变异系内的硝酸还原酶、转化酶及过氧化氢酶活性均显著地高于野生型。表明变异系对培养基中的碳源和氮源具有较高的利用能力。更多还原

【Abstract】 Three variant lines resistant to hydroxy-L-proline（Hyp） of tobacco （Nicotiana tabacum L. cv. CC77046, Hybrid（35） and Xuwu Xiaoye）, denoted as C^r-2, H^r-4 and X^r-1, have been selected from haploid callus cultures, which were submitted to ⁶⁰Co γ-ray irradiations before selecting for resistance to Hyp, by the multi-step direct selection system, and the corresponding non-irradiated callus cultures of these cultivars, which were subcultured on the normal medium, referred to as wild types, were designated respectively as C^w H^w and X^w.The Hyp-resistant variants showed a apparent and specific increase in the level of free proline. Under normal conditions the callus cultures of variants contained more than foue times as much free proline as did the wild types, and the proline overproduction trait could be expressed not only in the whole plants regenerated from the callus clones of variant but also in the secondary cultures induced from the regenerated plants through the transmission of regeneration. In addition, the percentage of free proline-nitrogen in total free amino-nitrogen was also evidently raised in the variant cultures, and the levels of several other amino acids were altered at the same time. Because the inhibition of haploid callus growth by Hyp could be partially reversed by proline, but not by other amino acids tested, the proline accumulation might be one of the important reasons why the variants were resistant to Hyp. The variant cultures contained elevated levels of protein,but the proline content of the total protein in the variant was not significantly and specificaly increa- sed.The activites of nitrate reductase, invertase as well as katalase in the callus cultures of C’-2 were significantly higher than those of C^w in the presence of 0.5 mM Hyp. It follows that the abilities of variant to utilize the carbon and nitrogen sources in the medium, were much stronger than those of wild type in the presence of Hyp.更多还原