Effects of low and elevated CO2 partial pressure on growth and reproduction of Arabidopsis thaliana from different elevations

Atmospheric CO₂ partial pressure may have been as low as 18 Pa during the Pleistocene and is expected to increase from 35 to 70 Pa before the end of the next century. Low CO₂ reduces the growth and reproduction of C₃ plants, whereas elevated CO₂ often increases growth and reproduction. Plants at high elevation are exposed to reduced CO₂ partial pressure and may be better adapted to the low CO₂ of the Pleistocene. We examined genotypes of Arabidopsis thaliana from different elevations for variation in growth and reproduction at the CO₂ levels of the Pleistocene, the present and the future. Genotypes exhibited limited genetic variation in the response of the production of biomass to changes in CO₂, but showed significant variation in reproductive characters. We found evidence that plants from high elevations may be better adapted to low CO₂ when considering seed number, which is an important component of fitness. Genotypes showed greater variation in the response of seed number between 35 and 20 Pa CO₂ compared to 35 and 70 Pa CO₂. We conclude that present-day C₃ annuals may have greater potential for evolution in response to the low CO₂ of the Pleistocene relative to the elevated CO₂ predicted for the future.     

转录组和代谢组联合解析苹果采后高浓度CO2伤害机制

环境气体浓度影响果蔬的贮藏保鲜期和品质,高浓度CO2长时间处理会造成果实的伤害,但具体的分子机制不清楚.本研究以高浓度CO2处理采后富士苹果为材料,利用Illumina Hiseq 4000高通量测序技术和非靶向代谢技术分别对苹果内部褐变果肉组织和对照组正常果肉组织进行转录组测序和代谢组学分析,解析苹果CO2伤害产生的...     

C4 photosynthesis in a single C3 cell is theoretically inefficient but may ameliorate internal CO2 diffusion limitations of C3 leaves

Attempts are being made to introduce C₄ photosynthetic characteristics into C₃ crop plants by genetic manipulation. This research has focused on engineering single‐celled C₄‐type CO₂ concentrating mechanisms into C₃ plants such as rice. Herein the pros and cons of such approaches are discussed with a focus on CO₂ diffusion, utilizing a mathematical model of single‐cell C₄ photosynthesis. It is shown that a high bundle sheath resistance to CO₂ diffusion is an essential feature of energy‐efficient C₄ photosynthesis. The large chloroplast surface area appressed to the intercellular airspace in C₃ leaves generates low internal resistance to CO₂ diffusion, thereby limiting the energy efficiency of a single‐cell C₄ concentrating mechanism, which relies on concentrating CO₂ within chloroplasts of C₃ leaves. Nevertheless the model demonstrates that the drop in CO₂ partial pressure, pCO₂, that exists between intercellular airspace and chloroplasts in C₃ leaves at high photosynthetic rates, can be reversed under high irradiance when energy is not limiting. The model shows that this is particularly effective at lower intercellular pCO₂. Such a system may therefore be of benefit in water‐limited conditions when stomata are closed and low intercellular pCO₂ increases photorespiration.     

Theoretical reconsiderations when estimating the mesophyll conductance to CO2 diffusion in leaves of C3 plants by analysis of combined gas exchange and chlorophyll fluorescence measurements

Existing methods to estimate the mesophyll conductance to CO₂ diffusion ( g _m) are often based on combined gas exchange and chlorophyll fluorescence measurements. However, estimations of average g _m by these methods are often unreliable either because the range of usable data is too narrow or because the estimations are very sensitive to measurement errors. We describe three method variants to estimate g _m, for which a wider range of data are usable. They use curve-fitting techniques, which minimise the sum of squared model deviations from the data for A (CO₂ assimilation rate) or for J (linear electron transport rate). Like the existing approaches, they are all based on common physiological principles assuming that electron transport limits A . The proposed variants were far less sensitive than the existing approaches to 'measurement noise' either created randomly in the generated data set or inevitably existing in real data sets. Yet, the estimates of g _m from the three variants differed by approximately 15%. Moreover, for each variant, a stoichiometric uncertainty in linear electron transport-limited photosynthesis can cause another 15% difference. Any estimation of g _m using gas exchange and chlorophyll fluorescence measurements should be considered with caution, especially when g _m is high.     

花粉发育的转录组研究进展

在受精过程中花粉通过其极性生长的花粉管将精细胞运送到胚囊启动双受精，除了在有性生殖过程中的重要作用外，花粉及其极性生长的花粉管也是研究植物生长发育的重要模式材料。随着模式植物拟南芥和水稻基因组测序的完成，在基因组水平上揭示花粉发育以及花粉管极性生长的分子基础已成为可能。经过最近几年的研究已初步明确了花粉转录组特征。本文主要讨论了拟南芥花粉转录组学的研究进展，以期帮助读者对花粉发育的研究有全面了解。