Chlorophyll deficiency in the maize elongated mesocotyl2 mutant is caused by a defective heme oxygenase and delaying grana stacking.
Chlorophyll deficiency in the maize elongated mesocotyl2 mutant is caused by a defective heme oxygenase and delaying grana stacking.
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DOI：
10.1371/journal.pone.0080107
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发表时间：
2013
期刊：
影响因子：
3.7
通讯作者：
Jin W
中科院分区：
文献类型：
--
作者：
Shi D;Zheng X;Li L;Lin W;Xie W;Yang J;Chen S;Jin W
黄化幼苗在第一次光照时启动基粒堆积和叶绿素合成，光敏色素在此过程中起重要作用。功能性光敏色素分别由两种组分生物合成。一种光敏色素是生物合成的脱辅基蛋白，另一种是生物合成的发色团，包括血红素加氧酶（HO）。我们通过图位克隆玉米伸长中胚轴2（elm2）突变体，分离了一个ho1同源基因。在elm2中的ho1同源物的cDNA测序显示31 bp的缺失。elm2幼苗对红光和远红光的去黄化反应被破坏，中胚轴明显伸长。elm2突变体的内源HO活性显著降低。转基因互补进一步证实了玉米ho1基因的功能障碍。此外，在elm2突变体中，非贴壁类囊体在幼苗期特异性地堆积。ho1基因中31 bp的缺失导致内源HO活性降低，并破坏了对红光和远红光的去黄化反应。非贴伏类囊体的特殊堆积表明，HO 1调控的叶绿素生物合成是通过协调血红素水平与基粒堆积的调控来实现的。
Etiolated seedlings initiate grana stacking and chlorophyll biosynthesis in parallel with the first exposure to light, during which phytochromes play an important role. Functional phytochromes are biosynthesized separately for two components. One phytochrome is biosynthesized for apoprotein and the other is biosynthesized for the chromophore that includes heme oxygenase (HO). We isolated a ho1 homolog by map-based cloning of a maize elongated mesocotyl2 (elm2) mutant. cDNA sequencing of the ho1 homolog in elm2 revealed a 31 bp deletion. De-etiolation responses to red and far-red light were disrupted in elm2 seedlings, with a pronounced elongation of the mesocotyl. The endogenous HO activity in the elm2 mutant decreased remarkably. Transgenic complementation further confirmed the dysfunction in the maize ho1 gene. Moreover, non-appressed thylakoids were specifically stacked at the seedling stage in the elm2 mutant. The 31 bp deletion in the ho1 gene resulted in a decrease in endogenous HO activity and disrupted the de-etiolation responses to red and far-red light. The specific stacking of non-appressed thylakoids suggested that the chlorophyll biosynthesis regulated by HO1 is achieved by coordinating the heme level with the regulation of grana stacking.
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