CORRELATION BETWEEN CAM-CYCLING AND PHOTOSYNTHETIC GAS-EXCHANGE IN 5 SPECIES OF TALINUM (PORTULACACEAE)
CORRELATION BETWEEN CAM-CYCLING AND PHOTOSYNTHETIC GAS-EXCHANGE IN 5 SPECIES OF TALINUM (PORTULACACEAE)
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DOI：
10.1104/pp.96.4.1118
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发表时间：
1991-08-01
期刊：
影响因子：
7.4
通讯作者：
MARTIN, CE
中科院分区：
文献类型：
--
作者：
HARRIS, FS;MARTIN, CE
在调查景天科植物酸代谢（CAM）-光合作用循环模式的生理生态意义时，对来自5种形态相似的土人参属植物的69株水分充足的植物进行了光合气体交换和苹果酸波动的监测。 与CAM不同，CAM循环中的大气CO2吸收仅发生在白天;在晚上，气孔关闭，呼吸CO2被重新捕获以形成苹果酸。 所有物种表现出类似的模式昼夜气体交换和过夜苹果酸积累，确认CAM循环的存在。 气体交换参数和苹果酸波动的物种平均值显着不同，白天气体交换最高的物种有最低的苹果酸积累，反之亦然。 此外，白天的CO2交换和蒸腾与夜间苹果酸波动的所有个人一起检查，以及在一个物种。 这表明，苹果酸可能会影响白天大气中CO2吸收和蒸腾的减少。 苹果酸波动和水分利用效率之间没有显着的相关性被发现，虽然一个非显着的趋势，增加苹果酸波动增加水分利用效率之间的物种平均值。 这项研究提供的证据表明，通过苹果酸CO2再循环与白天蒸腾水分损失在良好的浇水植物呈负相关。 因此，CAM循环可能是重要的生存在薄，经常干燥的土壤岩石露头上，这些植物发生。
Photosynthetic gas exchange and malic acid fluctuations were monitored in 69 well-watered plants from five morphologically similar species of Talinum in an investigation of the ecophysiological significance of the Crassulacean acid metabolism (CAM)-cycling mode of photosynthesis. Unlike CAM, atmospheric CO2 uptake in CAM-cycling occurs exclusively during the day; at night, the stomata are closed and respiratory CO2 is recaptured to form malic acid. All species showed similar patterns of day-night gas exchange and overnight malic acid accumulation, confirming the presence of CAM-cycling. Species averages for gas exchange parameters and malic acid fluctuation were significantly different such that the species with the highest daytime gas exchange had the lowest malic acid accumulation and vice versa. Also, daytime CO2 exchange and transpiration were negatively correlated with overnight malic acid fluctuation for all individuals examined together, as well as within one species. This suggests that malic acid may effect reductions in both atmospheric CO2 uptake and transpiration during the day. No significant correlation between malic acid fluctuation and water-use efficiency was found, although a nonsignificant trend of increasing water-use efficiency with increasing malic acid fluctuation was observed among species averages. This study provides evidence that CO2 recycling via malic acid is negatively correlated with daytime transpirational water losses in well-watered plants. Thus, CAM-cycling could be important for survival in the thin, frequently desiccated soils of rock outcrops on which these plants occur.