Jahan Eisrat, Amthor Jeffrey S, Farquhar Graham D, Trethowan Richard, Barbour Margaret M
Faculty of Agriculture and Environment, The University of Sydney, Private Bag 4011, Narellan, NSW 2567, Australia.
Research School of Biology, The Australian National University, Biology Place, Canberra, ACT 0200, Australia.
Funct Plant Biol. 2014 May;41(6):568-580. doi: 10.1071/FP13254.
CO2 diffusion from substomatal intercellular cavities to sites of carboxylation in chloroplasts (mesophyll conductance; gm) limits photosynthetic rate and influences leaf intrinsic water-use efficiency (A/gsw). We investigated genotypic variability of gm and effects of gm on A/gsw among eleven wheat (Triticum aestivum L.) genotypes under light-saturated conditions and at either 2 or 21% O2. Significant variation in gm and A/gsw was found between genotypes at both O2 concentrations, but there was no significant effect of O2 concentration on gm. Further, gm was correlated with photosynthetic rate among the 11 genotypes, but was unrelated to stomatal conductance. The effect of leaf age differed between genotypes, with gm being lower in older leaves for one genotype but not another. This study demonstrates a high level of variation in gm between wheat genotypes; 0.5 to 1.0μmolm-2s-1 bar-1. Further, leaf age effects indicate that great care must be taken to choose suitable leaves in studies of genotypic variation in gm and water-use efficiency.
二氧化碳从气孔下细胞间隙扩散到叶绿体中的羧化位点（叶肉导度；gm）限制了光合速率，并影响叶片的内在水分利用效率（A/gsw）。我们研究了在光饱和条件下以及2%或21%氧气浓度下，11个小麦（Triticum aestivum L.）基因型中gm的基因型变异以及gm对A/gsw的影响。在两种氧气浓度下，基因型之间的gm和A/gsw均存在显著差异，但氧气浓度对gm没有显著影响。此外，在11个基因型中，gm与光合速率相关，但与气孔导度无关。叶片年龄的影响因基因型而异，对于一个基因型，老叶中的gm较低，而对于另一个基因型则不然。本研究表明小麦基因型之间的gm存在高度变异；为0.5至1.0μmol m-2 s-1 bar-1。此外，叶片年龄效应表明，在研究gm和水分利用效率的基因型变异时，必须非常小心地选择合适的叶片。
