Vyas Dhiraj, Kumar Sanjay
Biotechnology Division, Institute of Himalayan Bioresource Technology, P.O. BOX: 6, Palampur- 176 061 (HP) INDIA.
Plant Physiol Biochem. 2005 Apr;43(4):383-8. doi: 10.1016/j.plaphy.2005.02.016. Epub 2005 Apr 7.
There is no literature available on the response of tea plant to low temperature. We studied the effect of low temperature on two clones of tea with contrasting periods of winter dormancy, a phenomenon in which the growth of apical shoots of tea is diminished during winter months. Clone 'Teenali 17/154' (TNL) showed shorter periods of winter dormancy than clone 'Kangra Jat' (KNJ). Low temperature (5 degrees C) resulted in increase of metabolic superoxide (O2*-) content and cellular damage (as measured by tetrazolium chloride reduction test) in both the clones, however, the increase was lesser in the case of TNL compared to KNJ. Activities of superoxide dismutase (SOD; EC 1.15.1.1), ascorbate peroxidase (APX; EC 1.11.1.11) and glutathione reductase (GR; EC 1.6.4.2) increased in both the clones in response to low temperature however, GR activity exhibited significant differences (P < 0.05) between the two clones. Low temperature caused increase in the intensity of various isozymes of SOD, APX and GR. A new isozyme of SOD (Cu/Zn type) was induced in both the clones at low temperature. Significantly higher GR activity in both the clones suggested a role of this enzyme in imparting better protection to tea at low temperature. Also, clonal variation for GR isozyme was observed between the clones. Based on these results it appears that TNL, a clone with relatively lesser period of winter dormancy experiences lesser oxidative stress in response to low temperature compared to KNJ, a clone with relatively higher period of winter dormancy.
目前尚无关于茶树对低温反应的文献。我们研究了低温对两个具有不同冬季休眠期的茶树无性系的影响，冬季休眠是茶树顶梢生长在冬季几个月中减弱的一种现象。无性系“Teenali 17/154”（TNL）的冬季休眠期比无性系“Kangra Jat”（KNJ）短。低温（5摄氏度）导致两个无性系的代谢超氧化物（O2*-）含量增加和细胞损伤（通过氯化三苯基四氮唑还原试验测定），然而，与KNJ相比，TNL的增加幅度较小。超氧化物歧化酶（SOD；EC 1.15.1.1）、抗坏血酸过氧化物酶（APX；EC 1.11.1.11）和谷胱甘肽还原酶（GR；EC 1.6.4.2）的活性在两个无性系中均因低温而增加，然而，GR活性在两个无性系之间表现出显著差异（P < 0.05）。低温导致SOD、APX和GR的各种同工酶强度增加。在低温下，两个无性系均诱导出一种新的SOD同工酶（铜/锌型）。两个无性系中GR活性显著较高，表明该酶在低温下对茶树具有更好的保护作用。此外，在无性系之间观察到GR同工酶的克隆变异。基于这些结果，似乎与具有相对较长冬季休眠期的无性系KNJ相比，具有相对较短冬季休眠期的无性系TNL在低温下经历的氧化应激较小。
