Serrano-Romero Erika A, Cousins Asaph B
Molecular Plant Sciences, Washington State University, Pullman, WA, 99164-4236, USA.
School of Biological Sciences, Washington State University, Pullman, WA, 99164-4236, USA.
New Phytol. 2020 Jun;226(6):1594-1606. doi: 10.1111/nph.16503. Epub 2020 Apr 11.
The cold acclimations of mesophyll conductance (g ), bundle-sheath conductance (g ) and the CO concentrating mechanism (CCM) of C plants have not been well studied. Here, we estimated the temperature response of g , g and leakiness (ϕ), the amount of concentrated CO that escapes the bundle-sheath cells, for the chilling-tolerant C plant Miscanthus × giganteus grown at 14 and 25°C. To estimate these parameters, we combined the C -enzyme-limited photosynthesis model and the Δ C discrimination model. These combined models were parameterised using in vitro activities of carbonic anhydrase (CA), pyruvate, phosphate dikinase (PPDK), ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO), and phosphoenolpyruvate carboxylase (PEPc). Cold-grown Miscanthus plants increased in vitro activities of RuBisCO and PPDK but decreased PEPc activity compared with warm-grown plants. Mesophyll conductance and g responded strongly to measurement temperatures but did not differ between plants from the two growth temperatures. Furthermore, modelling showed that ϕ increased with measurement temperatures for both cold-grown and warm-grown plants, but was only marginally larger in cold-grown compared with warm-grown plants. Our results in Miscanthus support that g and g are unresponsive to growth temperature and that the CCM is able to acclimate to cold through increased activity of PPDK and RuBisCO.
C4植物叶肉导度（gm）、维管束鞘导度（gb）和CO2浓缩机制（CCM）的冷驯化尚未得到充分研究。在此，我们估算了在14℃和25℃下生长的耐冷C4植物巨芒草的gm、gb和泄漏率（ϕ，即从维管束鞘细胞逸出的浓缩CO2量）的温度响应。为了估算这些参数，我们将C4-酶限制光合作用模型和Δ13C判别模型相结合。这些组合模型使用碳酸酐酶（CA）、丙酮酸磷酸双激酶（PPDK）、核酮糖-1,5-二磷酸羧化酶/加氧酶（RuBisCO）和磷酸烯醇式丙酮酸羧化酶（PEPc）的体外活性进行参数化。与温暖环境下生长的植株相比，冷环境下生长的巨芒草植株RuBisCO和PPDK的体外活性增加，但PEPc活性降低。叶肉导度和gb对测量温度反应强烈，但两种生长温度下的植株之间没有差异。此外，模型显示，冷环境和温暖环境下生长的植株的ϕ均随测量温度升高而增加，但冷环境下生长的植株仅比温暖环境下生长的植株略高。我们对巨芒草的研究结果支持gm和gb对生长温度无响应，且CCM能够通过增加PPDK和RuBisCO的活性来适应寒冷环境。
