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Mesophyll conductance in cotton bracts: anatomically-determined internal CO2 diffusion constraints on photosynthesis

发布者:绿洲生态发布时间:2018-08-15浏览次数:49

Mesophyll conductance in cotton bracts: anatomically-determined internal CO2 diffusion constraints on photosynthesis

Jimei Han, Zhangying Lei, Jaume Flexas, Yujie Zhang, Marc Carriquí, Wangfeng Zhang, Yali Zhang


Journal of Experimental Botany, ery296, https://doi.org/10.1093/jxb/ery296  Published:14 August 2018

Abstract:Mesophyll conductance (gm) has been shown to affect the photosynthetic capacity and thus the estimates of terrestrial carbon balance. While there have been some attempts to modelgmat the leaf and larger scales, the potential contribution ofgmon the photosynthesis of non-leaf green organs has not been studied. Here, we investigated the influence ofgmon photosynthesis of cotton bracts and how it is influenced by anatomical structures, by comparing leaf palisade and spongy mesophyll and bract tissue. Our results showed that photosynthetic capacity in bracts is much lower than in leaves, and thatgmis a limiting factor for bract photosynthesis to a similar extent as stomatal conductance is. Bract and the spongy tissue of leaves have lower mesophyll conductance than leaf palisade tissue due to the greater volume fraction of intercellular airspaces (fias), smaller chloroplasts, the lower surface of mesophyll cells and chloroplasts exposed to leaf intercellular air spaces (Sm/SandSc/S) and, perhaps, lower membrane permeability. Comparing bract with leaf spongy tissue, although bract has a larger cell wall thickness (Tcw), they have a similargmestimated from anatomical characteristics (gm_anatomy), likely due to the cumulative compensatory effects of subtle differences in each subcellular component, especially the chloroplast traits. These results show first evidence for anatomical constraints togmand photosynthesis in non-leaf green organs.


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