Photosynthesis Research Center, Key Laboratory of Photosynthesis and Environmental Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China; Key Laboratory of Crop Biology of Shandong Province, Shandong Agricultural University, Taian 271018, China.
Plant Sci. 2006 Sep;171(3):389-97. doi: 10.1016/j.plantsci.2006.04.010. Epub 2006 May 23.
Photosynthesis and its tolerance to photoinhibition, high temperature and drought stress of flag leaves were investigated in a wheat (Triticum aestivum L.) hybridization line (1-12) and its parents (Jing-411 and Xiaoyan-54). From the beginning of flowering to the 10th day, light-saturated CO(2) assimilation rate (P(max)) showed no significant decrease and P(max) of 1-12 was comparable to that of its parents. From the 20th day, P(max) decreased significantly and this decrease was much less in 1-12 than in its parents, whereas no decrease in chlorophyll content was observed in 1-12 and its parents on the 20th day, indicating that photo-oxidative damage occurred in 1-12 and its parents but 1-12 is more resistant to photo-oxidative damage than its parents. To further characterize photo-oxidative damage, tolerance to photoinhibition, high temperature and drought stress was compared in 1-12 and its parents. When exposed to high light (1400μmolm(-2)s(-1)), the maximal efficiency of PSII photochemistry (F(v)/F(m)) decreased significantly with increasing exposure time and such a decrease was much less in 1-12 than in its parents. When exposed to higher temperatures (30-45°C) for 15min, F(v)/F(m) started to decrease at 42°C in 1-12 and its parents. The greatest decrease in F(v)/F(m) was observed in Jing-411. 1-12 and Xiaoyan-54 showed a comparable decrease in F(v)/F(m). Similar results were also observed in the actual PSII efficiency (Φ(PSII)), photochemical quenching (q(P)) and non-photochemical quenching (q(N)). During exposure of detached leaves to air under room temperature conditions, relative water content decreased with increasing exposure time. However, such a decrease was greatest in Jing-411 followed by Xiaoyan-54, and 1-12. There were neither changes in F(v)/F(m) nor q(N) during water loss in the line and its parents. However, there was a decrease in Φ(PSII) and q(P) and greatest decrease was observed in Jing-411 followed by Xiaoyan-54, and 1-12. Also, the decrease in P(max) was greatest in Jing-411, followed by Xiaoyan-54, and 1-12 during water loss. In addition, the activities of ribulose-1,5-bisphosphate carboxylase, phosphoenolpyruvate carboxylase, pyruvate phosphate dikinase, NADP-malate dehydrogenase and NADP-malate enzyme were significantly higher in 1-12 than in its parents. The results in this study suggest that high resistance to photo-oxidative damage of the flag leaves in 1-12 may be the physiological basis for its high yield when grown in north China. Our results also suggest that parents can be selected for improved biochemical and physiological traits and crossed to high yielding agronomically elite materials which can be selected for higher performance in yield.
本研究以小麦杂交（1-12）及其亲本（京 411 和小偃 54）的旗叶为材料，研究了其光合作用及其对光抑制、高温和干旱胁迫的耐受性。从开花初期到第 10 天，1-12 的最大饱和 CO2 同化速率（P(max)）没有明显下降，与亲本相当。从第 20 天开始，P(max)显著下降，但 1-12 的下降幅度明显小于其亲本，而在第 20 天，1-12 及其亲本的叶绿素含量没有下降，表明 1-12 及其亲本发生了光氧化损伤，但 1-12 比其亲本更能耐受光氧化损伤。为了进一步描述光氧化损伤，比较了 1-12 及其亲本对光抑制、高温和干旱胁迫的耐受性。当暴露在高光（1400μmolm(-2)s(-1)）下时，随着暴露时间的增加，PSII 光化学的最大效率（F(v)/F(m)）显著下降，而 1-12 的下降幅度明显小于其亲本。当暴露在较高温度（30-45°C）下 15min 时，在 1-12 和其亲本中，F(v)/F(m)在 42°C 时开始下降。在京 411 中观察到最大的 F(v)/F(m)下降。1-12 和小偃 54 的 F(v)/F(m)下降幅度相当。在实际 PSII 效率（Φ(PSII)）、光化学猝灭（q(P)）和非光化学猝灭（q(N)）中也观察到了类似的结果。在室温条件下，离体叶片暴露在空气中时，相对含水量随暴露时间的增加而下降。然而，京 411 的下降幅度最大，其次是小偃 54，1-12 的下降幅度最小。在这条线和它的父母身上，在水分流失过程中，既没有 F(v)/F(m)的变化，也没有 q(N)的变化。然而，在 PSII 的Φ(PSII)和 q(P)下降，在京 411 中观察到最大的下降，其次是小偃 54，1-12。此外，在水分流失过程中，京 411 的 P(max)下降幅度最大，其次是小偃 54，1-12。此外，1-12 的核酮糖-1,5-二磷酸羧化酶、磷酸烯醇丙酮酸羧化酶、丙酮酸磷酸二激酶、NADP-苹果酸脱氢酶和 NADP-苹果酸酶的活性均显著高于其亲本。本研究结果表明，1-12 旗叶对光氧化损伤的高抗性可能是其在中国北方高产的生理基础。我们的研究结果还表明，可以选择具有改良生化和生理特性的亲本，并与高产的农业优良材料杂交，从而选择具有更高产量表现的材料。
