Photoinhibition and xanthophyll cycle activity in bayberry (Myrica rubra) leaves induced by high irradiance
Photoinhibition and xanthophyll cycle activity in bayberry (Myrica rubra) leaves induced by high irradiance
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DOI：
10.1007/s11099-006-0048-z
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发表时间：
2006-01-01
期刊：
影响因子：
2.7
通讯作者：
Shen, Y. -G.
中科院分区：
文献类型：
--
作者：
Guo, Y. -P.;Guo, D. -P.;Shen, Y. -G.
研究了高辐照度（HI，光合有效光子通量密度1300 μ mol m(-2) s(-1)）对果树杨梅叶片净光合速率（P-N）、叶绿素荧光参数和叶黄素循环组分的影响。 HI诱导光系统2（PS2）反应中心（RC）的光抑制和失活，其特征是PN降低，暗适应后最大荧光产率（F-m），PS2光化学效率（F-v/F-m）和PS2 Phi（PS2）量子产率降低，Q（A）（1 - q（P））还原态增加和非光化学猝灭 （NPQ）。初始荧光 (F-0) 在前 2 小时后显示出减少，随后从暴露于 HI 的第三小时开始增加。此外，HI暴露后，在叶子中观察到，比率(F-i - F-0)/(F-p - F-0)有更大的增加，该比率表示Q(B)非还原性PS2中心的比例，而Fi与Fp的斜率显着降低，Fp表示QA还原率。此外，HI 导致叶黄素循环色素池大小增加，并在照射期结束时持续升高玉米黄质 (Z)、蒽黄质 (A) 和脱环氧化态 (DES) 的含量。在 HI 期间，与相同条件下的对照叶片相比，观察到二硫苏糖醇 (DTT) 饲喂叶片的 F-m、F-v/F-m、OPS2、NPQ、F-i 与 F-p 的斜率、V+A+Z 和 DES 降低，而 F-0、1 - q(P)、比率 (F-i - F-0)/(F-p - F-0) 和 V 增加。因此，杨梅中HI引起的光抑制可能归因于PS2 RCs的失活，而光损伤的光保护主要与过量光子中叶黄素循环依赖性散热有关。
The effect of high irradiance (HI, photosynthetically active photon flux density of 1300 mu mol m(-2) s(-1)) on net photosynthetic rate (P-N), chlorophyll fluorescence parameters, and xanthophyll cycle components were studied in fruit tree bayberry leaves. HI induced the photoinhibition and inactivation of photosystem 2 (PS2) reaction centres (RCs), which was characterized by decreased PN, maximum yield of fluorescence after dark adaptation (F-m), photochemical efficiency of PS2 (F-v/F-m) and quantum yield of PS2 Phi(PS2) and increased reduction state of Q(A) (1 - q(P)) and non-photochemical quenching (NPQ). Initial fluorescence (F-0) showed a decrease after the first 2 h, and subsequently increased from the third hour exposure to HI. Furthermore, a greater increase in the ratio (F-i - F-0)/(F-p - F-0) which is an expression of the proportion of the Q(B) non-reducing PS2 centres, whereas a remarked decrease in the slope of Fi to Fp which represents the rate Of QA reduction was observed in leaves after HI exposure. Additionally, HI caused an increase in the pool size of the xanthophyll cycle pigments and sustained elevated contents of zeaxanthin (Z), antheraxanthin (A), and de-epoxidation state (DES) at the end of the irradiation period. During HI, decreased F-m, F-v/F-m, OPS2, NPQ, slope of F-i to F-p, V+A+Z, and DES, and increased F-0, 1 - q(P), ratio (F-i - F-0)/(F-p - F-0), and V were observed in dithiothreitol (DTT)-fed leaves compared to control ones under the same conditions. Hence photoinhibition caused by HI in bayberry was probably attributed to inactivation of PS2 RCs, and photoprotection from photodamage were mainly related to the xanthophyll cycle-dependent heat dissipation in excess photons.