Department of Botany, University of Iowa, Iowa City, Iowa 52242.
Plant Physiol. 1979 Aug;64(2):293-9. doi: 10.1104/pp.64.2.293.
Ecotypic differences in the photosynthetic carbon metabolism of Mollugo verticillata were studied. Variations in C(3) and C(4) cycle activity are apparently due to differences in the activities of enzymes associated with each pathway. Compared to C(4) plants, the activities of C(4) pathway enzymes were generally lower in M. verticillata, with the exception of the decarboxylase enzyme, NAD malic enzyme. The combined total carboxylase enzyme activity of M. verticillata was greater than that of C(3) plants, possibly accounting for the high photosynthetic rates of this species. Unlike either C(3) or C(4) plants, ribulose bisphosphate carboxylase was present in both mesophyll and bundle sheath cell chloroplasts in M. verticillata. The localization of this enzyme in both cells in this plant, in conjunction with an efficient C(4) acid decarboxylation mechanism most likely localized in bundle sheath cell mitochondria, may account for intermediate photorespiration levels previously observed in this species.
研究了皱叶酸模光合作用碳代谢的生态型差异。C3 和 C4 循环活性的变化显然是由于与每条途径相关的酶活性的不同。与 C4 植物相比，皱叶酸模中 C4 途径酶的活性通常较低，除了脱羧酶、NAD 苹果酸酶。皱叶酸模的总羧化酶活性大于 C3 植物，这可能是该物种高光合速率的原因。与 C3 或 C4 植物不同，核酮糖 1,5-二磷酸羧化酶存在于皱叶酸模的叶肉细胞和束鞘细胞叶绿体中。这种酶在该植物的这两种细胞中的定位，以及可能定位于束鞘细胞线粒体中的高效 C4 酸脱羧机制，可能解释了以前在该物种中观察到的中间光呼吸水平。
