Rajendrudu G, Prasad J S, Das V S
Department of Botany, School of Biological and Earth Sciences, Sri Venkateswara University, Tirupati 517 502, India.
Plant Physiol. 1986 Feb;80(2):409-14. doi: 10.1104/pp.80.2.409.
Two naturally occurring species of the genus Alternanthera, namely A. ficoides and A. tenella, were identified as C(3)-C(4) intermediates based on leaf anatomy, photosynthetic CO(2) compensation point (Gamma), O(2) response of small ghe, Cyrillic, light intensity response of small ghe, Cyrillic, and the activities of key enzymes of photosynthesis. A. ficoides and A. tenella exhibited a less distinct Kranz-like leaf anatomy with substantial accumulation of starch both in mesophyll and bundle sheath cells. Photosynthetic CO(2) compensation points of these two intermediate species at 29 degrees C were much lower than in C(3) plants and ranged from 18 to 22 microliters per liter. Although A. ficoides and A. tenella exhibited similar intermediacy in small ghe, Cyrillic, the apparent photorespiratory component of O(2) inhibition in A. ficoides is lower than in A. tenella. The small ghe, Cyrillic progressively decreases from 35 microliters per liter at lowest light intensity to 18 microliters per liter at highest light intensity in A. tenella. It was, however, constant in A. ficoides at 20 to 25 microliters per liter between light intensities measured. The rates of net photosynthesis at 21% O(2) and 29 degrees C by A. ficoides and A. tenella were 25 to 28 milligrams CO(2) per square decimeter per hour which are intermediate between values obtained for Tridax procumbens and A. pungens, C(3) and C(4) species, respectively. The activities of key enzymes of C(4) photosynthesis, phosphoenolpyruvate carboxylase, pyruvate Pi dikinase, NAD malic enzyme, NADP malic enzyme and phosphoenolpyruvate carboxykinase in the two intermediates, A. ficoides and A. tenella are very low or insignificant. Results indicated that the relatively low apparent photorespiratory component in these two species is presumably the basis for the C(3)-C(4) intermediate photosynthesis.
基于叶片解剖结构、光合二氧化碳补偿点（Γ）、小气孔导度的氧气响应、小气孔导度的光强响应以及光合作用关键酶的活性，两种自然存在的紫茉莉属物种，即小叶紫茉莉和细叶紫茉莉，被鉴定为C3 - C4中间型植物。小叶紫茉莉和细叶紫茉莉呈现出不太明显的类花环型叶片解剖结构，叶肉细胞和维管束鞘细胞中都有大量淀粉积累。这两个中间型物种在29℃时的光合二氧化碳补偿点远低于C3植物，范围在每升18至22微升之间。尽管小叶紫茉莉和细叶紫茉莉在小气孔导度方面表现出相似的中间型特征，但小叶紫茉莉中氧气抑制的表观光呼吸成分低于细叶紫茉莉。在细叶紫茉莉中，小气孔导度从最低光强下的每升35微升逐渐降低到最高光强下的每升18微升。然而，在小叶紫茉莉中，在所测光强之间，小气孔导度保持在每升20至25微升恒定。小叶紫茉莉和细叶紫茉莉在21%氧气浓度和29℃下的净光合速率分别为每平方分米每小时25至28毫克二氧化碳，这介于分别作为C3和C4物种的平卧银胶菊和针刺紫茉莉所获得的值之间。两种中间型植物小叶紫茉莉和细叶紫茉莉中C4光合作用关键酶磷酸烯醇式丙酮酸羧化酶、丙酮酸磷酸双激酶、NAD苹果酸酶、NADP苹果酸酶和磷酸烯醇式丙酮酸羧激酶的活性非常低或不显著。结果表明，这两个物种中相对较低的表观光呼吸成分可能是C3 - C4中间型光合作用的基础。
