Jha A B, Dubey R S
Department of Biochemistry, Faculty of Science, Banaras Hindu University, Varanasi, India.
J Plant Physiol. 2004 Jul;161(7):867-72. doi: 10.1016/j.jplph.2004.01.004.
We studied in the seedlings of two rice cultivars (Malviya-36 and Pant-12) the effect of increasing levels of arsenic in situ on the content of sugars and the activity of several enzymes of starch and sucrose metabolism: alpha-amylase (EC 3.2.1.1), beta-amylase (EC 3.2.1.2), starch phosphorylase (EC 2.4.1.1), acid invertase (EC 3.2.1.26), sucrose synthase (EC 2.4.1.13) and sucrose phosphate synthase (EC 2.4.1.14). During a growth period of 10-20 d As2O3 at 25 and 50 microM in the growth medium caused an increase in reducing, non-reducing and total soluble sugars. An increased conversion of non-reducing to reducing sugars was observed concomitant with As toxicity. The activities of alpha-amylase, beta-amylase and sucrose phosphate synthase declined, whereas starch phosphorylase, acid invertase and sucrose synthase were found to be elevated. Results indicate that in rice seedlings arsenic toxicity causes perturbations in carbohydrate metabolism leading to the accumulation of soluble sugars by altering enzyme activity. Sucrose synthase possibly plays a positive role in synthesis of sucrose under As-toxicity.
我们研究了在两个水稻品种（Malviya - 36和Pant - 12）的幼苗中，原位增加砷水平对糖类含量以及淀粉和蔗糖代谢的几种酶活性的影响：α -淀粉酶（EC 3.2.1.1）、β -淀粉酶（EC 3.2.1.2）、淀粉磷酸化酶（EC 2.4.1.1）、酸性转化酶（EC 3.2.1.26）、蔗糖合酶（EC 2.4.1.13）和蔗糖磷酸合酶（EC 2.4.1.14）。在10 - 20天的生长期间，生长培养基中25和50微摩尔的As2O3导致还原糖、非还原糖和总可溶性糖增加。随着砷毒性的增加，观察到非还原糖向还原糖的转化率增加。α -淀粉酶、β -淀粉酶和蔗糖磷酸合酶的活性下降，而淀粉磷酸化酶、酸性转化酶和蔗糖合酶被发现活性升高。结果表明，在水稻幼苗中，砷毒性导致碳水化合物代谢紊乱，通过改变酶活性导致可溶性糖积累。在砷毒性下，蔗糖合酶可能在蔗糖合成中起积极作用。
