Genotypic variation within Zea mays for susceptibility to and rate of recovery from chill-induced photoinhibition of photosynthesis
Genotypic variation within Zea mays for susceptibility to and rate of recovery from chill-induced photoinhibition of photosynthesis
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DOI：
10.1034/j.1399-3054.1999.106411.x
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发表时间：
1999-08-01
影响因子：
6.4
通讯作者：
Long, SP
中科院分区：
文献类型：
--
作者：
Aguilera, C;Stirling, CM;Long, SP
在温室盆栽条件下，6个玉米品种在日照期间的平均温度为22℃+/-2℃，最低光合光量子通量密度(Q)为400mmolm(-2)S(-1)。将植物置于7℃、Q1000mmolm(-2)S(-1)处理6h，然后在25℃、Q200mmolm(-2)S(-1)条件下恢复光抑制，诱导出依赖于低温的光抑制。在光抑制处理前的室温和恢复期0~24 h的6个采样间隔下，测定了叶片的气体交换和叶绿素荧光。在恢复期还测量了相对含水量(RWC)。结果表明，玉米幼苗对低温光合作用光抑制的敏感性和恢复速率存在显著的基因型差异。来自墨西哥高地的高地池塘最不容易受到寒冷诱导的光抑制的影响，但恢复速度最慢。杂交种LG11的恢复率最高，而自交系ZPF307对冷害光抑制最敏感，光抑制敏感度和随后的恢复率至少是部分独立的，这表明对改良基因型的选择需要对耐性和恢复能力进行独立选择。虽然叶绿素荧光提供了一种更快速的方法来评估光抑制的发生，但它在区分不同类型对光抑制的敏感性方面不如直接气体交换测量光合作用最大量子效率(Phi)有效，特别是在最脆弱的基因类型，如ZPF307，由低温和高Q处理引起的水分胁迫似乎损害了恢复过程。气孔导度的下降(g(S))导致胞间CO2浓度(C(I))的显著下降，尽管这种下降并不是如此极端，以至于限制了用于测定phi的光强下的光合作用速率。然而，斑块中气孔的关闭，造成了CO(2)供应的局部限制，这可以解释在光抑制处理后立即某些基因型的叶绿素荧光与量子效率之间相关性较差的原因。
Six genotypes of Zea mays L. were grown in pots inside a glasshouse at a mean temperature of 22 +/- 2 degrees C and a minimum photosynthetic photon flux density (Q) during the daylight period of 400 mu mol m(-2) s(-1). Chilling-dependent photoinhibition was induced by exposing plants to a temperature of 7 degrees C and a Q of 1000 mu mol m(-2) s(-1) for 6 h, Recovery from photoinhibition was then followed at a temperature of 25 degrees C and a Q of 200 mu mol m(-2) s(-1). Leaf gas exchange and chlorophyll fluorescence were measured on attached leaves at room temperature prior to the photoinhibitory treatments and at 6 sampling intervals from 0 to 24 h during the recovery period. The relative water content (RWC) was also measured during the recovery period. The results showed a significant genotypic variation in the susceptibility to and rate of recovery from chilling-dependent photoinhibition of photosynthesis in Zea mays seedlings. The Highland Pool la from highland sites in Mexico was the least susceptible to chill-induced photoinhibition, but had the slowest rate of recovery. The hybrid variety LG11 showed the highest rate of recovery, whilst the inbred line ZPF307 was the most susceptible to chill-induced photoinhibition, Susceptibility to photoinhibition and subsequent recovery were at least partially independent, suggesting that selection for improved genotypes will require independent selection for both tolerance and capacity for recovery. Although chlorophyll fluorescence provided a more rapid method of assessing the occurrence of photoinhibition, it was not as effective as direct gas-exchange measurements of the maximum quantum yield of photosynthesis (Phi) in separating genotypes with respect to their susceptibility to photoinhibition, especially in the most vulnerable genotypes such as ZPF307, Water stress induced by chilling and high Q treatments appeared to impair the recovery processes. Decreases in stomatal conductance (g(s)) produce a significant decrease in intercellular CO(2) concentration (C(i)), although this decrease was never so extreme that it limited photosynthetic rates at the light intensities used to determine Phi. Nevertheless, closure of stomata in patches, producing local restriction of CO(2) supply, would explain the poor correlation between chlorophyll fluorescence and quantum yield measurements in some genotypes immediately after photoinhibitory treatments.