Dubbe D R, Farquhar G D, Raschke K
MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, Michigan 48824.
Plant Physiol. 1978 Sep;62(3):413-7. doi: 10.1104/pp.62.3.413.
Gains of the feedback loops involving intercellular CO(2) concentration on one hand, and CO(2) assimilation and stomata on the other (= assimilation loop with gain [G(A)] and conductance loop with gain [G(g)]) were determined in detached leaves of Amaranthus powelli S. Wats., Avena sativa L., Gossypium hirsutum L., Xanthium strumarium L., and Zea mays in the absence and presence of 10(-5)m (+/-) abscisic acid (ABA) in the transpiration stream. Determinations were made for an ambient CO(2) concentration of 300 microliters per liter. In the absence of ABA, stomata were insensitive to CO(2) (G(g) between 0.00 and -0.02) in A. sativa, G. hirsutum, and X. strumarium, sensitive in A powelli (G(g) = -0.46), and very sensitive in Z. mays (G(g) = -3.6). Addition of ABA increased the absolute values of the gain of the conductance loop in A. powelli (G(g) = -2.0), G. hirsutum (G(g) = -0.31), and X. strumarium (G(g) = -1.14). Stomata closed completely in A. sativa. In Z. mays, G(g) decreased after application of ABA to a value of -0.86, but stomatal sensitivity to CO(2) increased for intercellular CO(2) concentrations < 100 microliters per liter. The gain of the assimilation loop increased after application of ABA in all cases, from values between 0.0 (A. powelli) and -0.21 (Z. mays) in the absence of ABA to values between -0.19 (A. powelli) and -0.43 (Z. mays) in the presence of ABA. In none of the species examined did ABA affect the photosynthetic capacity of the leaves.The application of ABA caused stomatal narrowing which affected transpiration more than the assimilation of CO(2). In the case of A. powelli the transpiration ratio decreased without a concomitant reduction of the assimilation rate.
测定了 Powell 苋（Amaranthus powelli S. Wats.）、燕麦（Avena sativa L.）、陆地棉（Gossypium hirsutum L.）、苍耳（Xanthium strumarium L.）和玉米（Zea mays）离体叶片中，一方面涉及细胞间二氧化碳浓度，另一方面涉及二氧化碳同化和气孔的反馈回路增益（即具有增益[G(A)]的同化回路和具有增益[G(g)]的导度回路），测定时蒸腾流中存在和不存在 10⁻⁵m（±）脱落酸（ABA）。测定时环境二氧化碳浓度为 300 微升/升。在没有 ABA 的情况下，燕麦、陆地棉和苍耳的气孔对二氧化碳不敏感（G(g)在 0.00 至 -0.02 之间），Powell 苋敏感（G(g) = -0.46），玉米非常敏感（G(g) = -3.6）。添加 ABA 增加了 Powell 苋（G(g) = -2.0）、陆地棉（G(g) = -0.31）和苍耳（G(g) = -1.14）导度回路增益的绝对值。燕麦的气孔完全关闭。在玉米中，施用 ABA 后 G(g)降至 -0.86，但对于细胞间二氧化碳浓度<100 微升/升，气孔对二氧化碳的敏感性增加。在所有情况下，施用 ABA 后同化回路的增益都增加了，从没有 ABA 时 0.0（Powell 苋）至 -0.21（玉米）的值，增加到有 ABA 时 -0.19（Powell 苋）至 -0.43（玉米）的值。在所研究的任何物种中，ABA 都不会影响叶片的光合能力。ABA 的施用导致气孔变窄，对蒸腾作用的影响大于对二氧化碳同化的影响。就 Powell 苋而言，蒸腾比率降低，而同化速率没有相应降低。
