Contribution and consequences of xylem‐transported CO 2 assimilation for C 3 plants
Contribution and consequences of xylem‐transported CO 2 assimilation for C 3 plants
复制标题
木质部转运的 CO 2 同化对 C 3 植物的贡献和后果
DOI：
10.1111/nph.15907
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发表时间：
2019
期刊：
影响因子：
9.4
通讯作者：
Hanson, David T.
中科院分区：
文献类型：
--
作者：
Stutz, Samantha S.;Hanson, David T.
传统上，叶子被认为是由大气和呼吸作用提供二氧化碳进行光合作用的。然而，最近的研究表明，木质部也通过大量的水流将大量的无机碳运输到叶片中。然而，很少有人知道的动态和比例的木质部运输的CO2被同化，将美洲黑杨和甘蓝型油菜的切叶分别置于KCl或三种[NaH_（13）CO_3]中的一种中，溶解在水中的溶液，使用可调谐二极管激光吸收，在真实的时间内，通过光和CO2响应曲线同时测量木质部运输的CO2的同化和流出随着木质部[13 CO2 *]和蒸腾量的增加，木质部运输CO2的同化率和外排率均增加。在饱和光照条件下，两种植物利用木质部运输的CO2同化的速率最高时[13 CO2 *]占总同化量的2.5%，木质部运输的CO2大部分被同化，与呼吸作用相比，外排量很小。木质部运输的CO2的同化包括总光合作用的一小部分，但当CO2限制时可能更重要。
Traditionally, leaves were thought to be supplied with CO2for photosynthesis by the atmosphere and respiration. Recent studies, however, have shown that the xylem also transports a significant amount of inorganic carbon into leaves through the bulk flow of water. However, little is known about the dynamics and proportion of xylem‐transported CO2that is assimilated, vs simply lost to transpiration.Cut leaves ofPopulus deltoidesandBrassica napuswere placed in either KCl or one of three [NaH13CO3] solutions dissolved in water to simultaneously measure the assimilation and the efflux of xylem‐transported CO2exiting the leaf across light and CO2response curves in real‐time using a tunable diode laser absorption spectroscope.The rates of assimilation and efflux of xylem‐transported CO2increased with increasing xylem [13CO2*] and transpiration. Under saturating irradiance, rates of assimilation using xylem‐transported CO2accounted forc.2.5% of the total assimilation in both species in the highest [13CO2*].The majority of xylem‐transported CO2is assimilated, and efflux is small compared to respiration. Assimilation of xylem‐transported CO2comprises a small portion of total photosynthesis, but may be more important when CO2is limiting.