植物通過(guò)葉子表面微小的呼吸孔可以吸收二氧化碳進(jìn)行光合作用,，但是植物每吸收一分子的二氧化碳,，植物自身都會(huì)從呼吸孔中蒸發(fā)掉大量的(約95%)水分子。如果環(huán)境中CO2的量很充足,，那么水分的蒸發(fā)量將會(huì)下降,，一直以來(lái)研究人員都不清楚其中的奧秘。
最近一項(xiàng)12月13日Nature Cell Biology雜志的研究報(bào)告,，生物學(xué)家發(fā)現(xiàn)模式植物擬南芥(Arabidopsis)中存在著一類碳酸酐酶(carbonic anhydrases),，有助于植物在二氧化碳較高的環(huán)境中更有效地利用水分,。
據(jù)Julian Schroeder介紹，許多植物對(duì)CO2的反應(yīng)非常弱,，因此,，即使現(xiàn)在大氣中的CO2水平要比工業(yè)革命以前高得多，并且CO2含量還在增加,，植物也并未充分利用這些含量升高的CO2,。
這項(xiàng)由Schroeder主持的課題組發(fā)現(xiàn)碳酸酐酶能夠和CO2反應(yīng)，從而使被打開的氣孔附近的細(xì)胞關(guān)閉,。碳酸酐酶能使CO2轉(zhuǎn)變成為碳酸氫鹽和質(zhì)子,。植物若是缺失碳酸酐酶相應(yīng)的基因，那么即使空氣中CO2的濃度上升,，植物也不能有效的利用CO2,。
雖然在多種植物細(xì)胞中都發(fā)現(xiàn)了碳酸酐酶，但該課題組表明,，碳酸酐酶能夠直接作用于能控制每一個(gè)呼吸孔開閉的保衛(wèi)細(xì)胞(guard cells),。研究人員還發(fā)現(xiàn)，保衛(wèi)細(xì)胞中如果導(dǎo)入多余的碳酸酐酶基因,，將能使植物更有效的利用水分,。（生物谷Bioon.com）
生物谷推薦原始出處：
Nature Cell Biology 13 December 2009 | doi:10.1038/ncb2009
Carbonic anhydrases are upstream regulators of CO2-controlled stomatal movements in guard cells
Honghong Hu1,6, Aurélien Boisson-Dernier1,2,6, Maria Israelsson-Nordstr?m1,3,6, Maik B?hmer1,7, Shaowu Xue1,4,7, Amber Ries1, Jan Godoski1, Josef M. Kuhn1,5 & Julian I. Schroeder1
The continuing rise in atmospheric CO2 causes stomatal pores in leaves to close and thus globally affects CO2 influx into plants, water use efficiency and leaf heat stress1, 2, 3, 4. However, the CO2-binding proteins that control this response remain unknown. Moreover, which cell type responds to CO2, mesophyll or guard cells, and whether photosynthesis mediates this response are matters of debate5, 6, 7, 8. We demonstrate that Arabidopsis thaliana double-mutant plants in the β-carbonic anhydrases βCA1 and βCA4 show impaired CO2-regulation of stomatal movements and increased stomatal density, but retain functional abscisic-acid and blue-light responses. βCA-mediated CO2-triggered stomatal movements are not, in first-order, linked to whole leaf photosynthesis and can function in guard cells. Furthermore, guard cell βca-overexpressing plants exhibit instantaneous enhanced water use efficiency. Guard cell expression of mammalian αCAII complements the reduced sensitivity of ca1 ca4 plants, showing that carbonic anhydrase-mediated catalysis is an important mechanism for βCA-mediated CO2-induced stomatal closure and patch clamp analyses indicate that CO2/HCO3? transfers the signal to anion channel regulation. These findings, together with ht1-2 (ref. 9) epistasis analysis demonstrate that carbonic anhydrases function early in the CO2 signalling pathway, which controls gas-exchange between plants and the atmosphere.
