Online CO2 and H2O oxygen isotope fractionation allows estimation of mesophyll conductance in C4 plants, and reveals that mesophyll conductance decreases as leaves age in both C4 and C3 plants
Online CO2 and H2O oxygen isotope fractionation allows estimation of mesophyll conductance in C4 plants, and reveals that mesophyll conductance decreases as leaves age in both C4 and C3 plants
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DOI：
10.1111/nph.13830
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发表时间：
2016-05-01
期刊：
影响因子：
9.4
通讯作者：
von Caemmerer, Susanne
中科院分区：
文献类型：
--
作者：
Barbour, Margaret M.;Evans, John R.;von Caemmerer, Susanne
叶肉电导率显着，并限制光合作用，但我们目前还没有可靠的方法来测量C-4植物。开发了一种在线氧同位素技术，以量化C-4植物的叶肉电导率，并提供C-3植物的替代估计。该技术相比，在三个C-3物种的一个既定的碳同位素方法。C-4和C-3植物叶肉电导率随叶片从完全展开到衰老而下降。在棉花叶片中，同时测量碳和氧同位素的歧视允许分配的总电导到叶绿体到细胞壁和质膜与叶绿体膜组件，如果CO2被假定为同位素平衡与胞质水，和分区保持稳定与叶龄。氧同位素技术允许估计叶肉电导在C-4植物，并结合成熟的碳同位素技术，可以提供额外的信息叶肉电导在C-3植物。
Mesophyll conductance significantly, and variably, limits photosynthesis but we currently have no reliable method of measurement for C-4 plants. An online oxygen isotope technique was developed to allow quantification of mesophyll conductance in C-4 plants and to provide an alternative estimate in C-3 plants. The technique is compared to an established carbon isotope method in three C-3 species. Mesophyll conductance of C-4 species was similar to that in the C-3 species measured, and declined in both C-4 and C-3 species as leaves aged from fully expanded to senescing. In cotton leaves, simultaneous measurement of carbon and oxygen isotope discrimination allowed the partitioning of total conductance to the chloroplasts into cell wall and plasma membrane versus chloroplast membrane components, if CO2 was assumed to be isotopically equilibrated with cytosolic water, and the partitioning remained stable with leaf age. The oxygen isotope technique allowed estimation of mesophyll conductance in C-4 plants and, when combined with well-established carbon isotope techniques, may provide additional information on mesophyll conductance in C-3 plants.