Regulation of Carotenoid Composition and Shoot Branching in Arabidopsis by a Chromatin Modifying Histone Methyltransferase, SDG8
Regulation of Carotenoid Composition and Shoot Branching in Arabidopsis by a Chromatin Modifying Histone Methyltransferase, SDG8
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DOI：
10.1105/tpc.108.063131
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发表时间：
2009-01-01
期刊：
影响因子：
11.6
通讯作者：
Pogson, Barry J.
中科院分区：
文献类型：
--
作者：
Cazzonelli, Christopher I.;Cuttriss, Abby J.;Pogson, Barry J.
类胡萝卜素对植物的生存至关重要，类胡萝卜素的组成与发育阶段、组织和环境刺激有关。我们报道了类胡萝卜素叶绿体调控基因CCR1的克隆。ccr1突变体增加了茎的分枝，改变了类胡萝卜素的组成，即叶片中叶黄素的减少和顺式胡萝卜素在暗生长幼苗中的积累。CCR1基因先前被分离为“短天早花”，编码组蛋白甲基转移酶（SET DOMAIN GROUP 8），甲基化赖氨酸4和/或36 （H3K4和H3K36）上的组蛋白H3。ccr1植株类胡萝卜素异构酶（CRTISO）翻译起始位点周围的三甲基- h3k4减少，二甲基- h3k4增加，这与CRTISO mRNA水平低有关。ccr1的微阵列显示85个基因下调，包括CRTISO和与信号传导和发育相关的基因，只有28个基因上调。CRTISO转录物丰度的降低解释了类胡萝卜素谱的改变。茎枝分枝的变化与更多的腋生分枝突变体有关，但类胡萝卜素谱的改变可能部分影响茎枝分枝，这可能是由于类胡萝卜素底物独角甾内酯的生物合成受到干扰。这些结果与SDG8通过修饰CRTISO等关键基因周围的染色质调控芽部分生组织活性和类胡萝卜素的生物合成一致。因此，叶黄素（高等植物中最丰富的类胡萝卜素，对光合作用和光保护至关重要）的水平似乎受到拟南芥染色质修饰酶的调节。
Carotenoid pigments are critical for plant survival, and carotenoid composition is tuned to the developmental stage, tissue, and to environmental stimuli. We report the cloning of the CAROTENOID CHLOROPLAST REGULATORY1 (CCR1) gene. The ccr1 mutant has increased shoot branching and altered carotenoid composition, namely, reduced lutein in leaves and accumulation of cis-carotenes in dark-grown seedlings. The CCR1 gene was previously isolated as EARLY FLOWERING IN SHORT DAYS and encodes a histone methyltransferase (SET DOMAIN GROUP 8) that methylates histone H3 on Lys 4 and/or 36 (H3K4 and H3K36). ccr1 plants show reduced trimethyl-H3K4 and increased dimethyl-H3K4 surrounding the CAROTENOID ISOMERASE (CRTISO) translation start site, which correlates with low levels of CRTISO mRNA. Microarrays of ccr1 revealed the downregulation of 85 genes, including CRTISO and genes associated with signaling and development, and upregulation of just 28 genes. The reduction in CRTISO transcript abundance explains the altered carotenoid profile. The changes in shoot branching are additive with more axillary branching mutants, but the altered carotenoid profile may partially affect shoot branching, potentially by perturbed biosynthesis of the carotenoid substrates of strigolactones. These results are consistent with SDG8 regulating shoot meristem activity and carotenoid biosynthesis by modifying the chromatin surrounding key genes, including CRTISO. Thus, the level of lutein, the most abundant carotenoid in higher plants that is critical for photosynthesis and photoprotection, appears to be regulated by a chromatin modifying enzyme in Arabidopsis thaliana.