Lutein Accumulation in the Absence of Zeaxanthin Restores Nonphotochemical Quenching in the Arabidopsis thaliana npq1 Mutant
Lutein Accumulation in the Absence of Zeaxanthin Restores Nonphotochemical Quenching in the Arabidopsis thaliana npq1 Mutant
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DOI：
10.1105/tpc.109.066571
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发表时间：
2009-06-01
期刊：
影响因子：
11.6
通讯作者：
Niyogi, Krishna K.
中科院分区：
文献类型：
--
作者：
Li, Zhirong;Ahn, Tae Kyu;Niyogi, Krishna K.
植物通过热耗散来保护自己免受过量吸收的光能的影响，热耗散通过叶绿素荧光的非光化学猝灭（NPQ）来测量。 NPQ 的主要成分 qE 是由过量光照下的高跨类囊体 Delta pH 值诱导的，并且取决于叶黄素循环，其中紫黄质和蒽黄质被深度氧化形成玉米黄质。为了研究 qE 的叶黄素依赖性，我们鉴定了 zeaxanthin-less1 (szl1) 抑制子作为拟南芥 npq1 突变体的抑制子，该突变体缺乏玉米黄质。 szl1 npq1 植物的 qE 部分恢复，但缺乏玉米黄质，并且紫黄质、蒽黄质和新黄质含量较低。然而，它们比野生型积累了更多的叶黄素和α-胡萝卜素。 szl1 的番茄红素β-环化酶 (LCYB) 基因中包含一个点突变。根据色素分析，LCYB 似乎是主要的番茄红素 β-环化酶，并且不参与新黄质合成。相对于野生型，szl1 npq1 中的 Lhcb4 (CP29) 和 Lhcb5 (CP26) 蛋白水平降低了 50%，而其他 Lhcb 蛋白则以野生型水平存在。对类胡萝卜素自由基阳离子形成和叶片吸光度变化的分析强烈表明，较高量的叶黄素替代了 qE 中的玉米黄质，这意味着 qE 中的直接作用，以及对类胡萝卜素结构特性较弱敏感的机制。
Plants protect themselves from excess absorbed light energy through thermal dissipation, which is measured as nonphotochemical quenching of chlorophyll fluorescence (NPQ). The major component of NPQ, qE, is induced by high transthylakoid Delta pH in excess light and depends on the xanthophyll cycle, in which violaxanthin and antheraxanthin are deepoxidized to form zeaxanthin. To investigate the xanthophyll dependence of qE, we identified suppressor of zeaxanthin-less1 (szl1) as a suppressor of the Arabidopsis thaliana npq1 mutant, which lacks zeaxanthin. szl1 npq1 plants have a partially restored qE but lack zeaxanthin and have low levels of violaxanthin, antheraxanthin, and neoxanthin. However, they accumulate more lutein and alpha-carotene than the wild type. szl1 contains a point mutation in the lycopene beta-cyclase (LCYB) gene. Based on the pigment analysis, LCYB appears to be the major lycopene beta-cyclase and is not involved in neoxanthin synthesis. The Lhcb4 (CP29) and Lhcb5 (CP26) protein levels are reduced by 50% in szl1 npq1 relative to the wild type, whereas other Lhcb proteins are present at wild-type levels. Analysis of carotenoid radical cation formation and leaf absorbance changes strongly suggest that the higher amount of lutein substitutes for zeaxanthin in qE, implying a direct role in qE, as well as a mechanism that is weakly sensitive to carotenoid structural properties.