Grupo Interações Planta-Ambiente - Plant Stress, Centro de Ambiente, Agricultura e Desenvolvimento - BioTrop, Instituto de Investigação Científica Tropical, I.P., Oeiras, Portugal.
PLoS One. 2013 Dec 6;8(12):e82712. doi: 10.1371/journal.pone.0082712. eCollection 2013.
Coffee is one of the world's most traded agricultural products. Modeling studies have predicted that climate change will have a strong impact on the suitability of current cultivation areas, but these studies have not anticipated possible mitigating effects of the elevated atmospheric [CO2] because no information exists for the coffee plant. Potted plants from two genotypes of Coffea arabica and one of C. canephora were grown under controlled conditions of irradiance (800 μmol m(-2) s(-1)), RH (75%) and 380 or 700 μL CO2 L(-1) for 1 year, without water, nutrient or root development restrictions. In all genotypes, the high [CO2] treatment promoted opposite trends for stomatal density and size, which decreased and increased, respectively. Regardless of the genotype or the growth [CO2], the net rate of CO2 assimilation increased (34-49%) when measured at 700 than at 380 μL CO2 L(-1). This result, together with the almost unchanged stomatal conductance, led to an instantaneous water use efficiency increase. The results also showed a reinforcement of photosynthetic (and respiratory) components, namely thylakoid electron transport and the activities of RuBisCo, ribulose 5-phosphate kinase, malate dehydrogenase and pyruvate kinase, what may have contributed to the enhancements in the maximum rates of electron transport, carboxylation and photosynthetic capacity under elevated [CO2], although these responses were genotype dependent. The photosystem II efficiency, energy driven to photochemical events, non-structural carbohydrates, photosynthetic pigment and membrane permeability did not respond to [CO2] supply. Some alterations in total fatty acid content and the unsaturation level of the chloroplast membranes were noted but, apparently, did not affect photosynthetic functioning. Despite some differences among the genotypes, no clear species-dependent responses to elevated [CO2] were observed. Overall, as no apparent sign of photosynthetic down-regulation was found, our data suggest that Coffea spp. plants may successfully cope with high [CO2] under the present experimental conditions.
咖啡是全球交易量最大的农产品之一。建模研究预测，气候变化将对当前种植区的适宜性产生强烈影响，但这些研究没有考虑到大气[CO2]升高可能产生的缓解作用，因为咖啡植物没有相关信息。来自两个阿拉比卡咖啡基因型和一个罗布斯塔咖啡基因型的盆栽植物在光照（800 μmol m(-2) s(-1)）、相对湿度（75%）和 380 或 700 μL CO2 L(-1)的受控条件下生长了 1 年，没有水分、养分或根系发育的限制。在所有基因型中，高[CO2]处理促进了气孔密度和大小的相反趋势，分别减小和增大。无论基因型或生长[CO2]如何，当在 700 比在 380 μL CO2 L(-1)下测量时，净 CO2同化率增加（34-49%）。这一结果，再加上气孔导度几乎不变，导致水分利用效率提高。结果还表明，光合（和呼吸）组分得到了加强，即类囊体电子传递和 RuBisCo、核酮糖 5-磷酸激酶、苹果酸脱氢酶和丙酮酸激酶的活性增强，这可能有助于提高电子传递、羧化和光合能力的最大速率在高[CO2]下，尽管这些反应取决于基因型。光合系统 II 效率、光化学反应所驱动的能量、非结构性碳水化合物、光合色素和膜通透性对[CO2]供应没有响应。注意到总脂肪酸含量和叶绿体膜的不饱和水平发生了一些变化，但显然没有影响光合作用功能。尽管不同基因型之间存在一些差异，但没有观察到对高[CO2]的明显依赖于物种的反应。总体而言，由于没有发现光合作用下调的明显迹象，我们的数据表明，在当前的实验条件下，咖啡属植物可能成功应对高[CO2]。
