Background

Chloroplast development is coordinately regulated by plastid- and nuclear-encoding genes. Although many regulators have been reported to be involved in chloroplast development, new factors remain to be identified, given the complexity of this process.

Results

In this study, we characterized a rice mutant lethal albinic seedling 1(las1)form of a 4-hydroxy-3-methylbut-2-enyl diphosphate reductase (OsHMBPP) that was targeted to the chloroplasts. The LAS1 mutation caused the albino lethal phenotype in seedlings. Transmission electron microscopy indicated that las1 were defective in early chloroplast development. LAS1 is preferentially expressed in leaves, implying its role in controlling chloroplast development. The expression levels of many chloroplast-encoded genes were altered significantly in las1. The expression levels of nuclear-encoded gene involved in Chl biosynthesis were also decreased in las1. We further investigated plastidic RNA editing in las1 and found that the edit efficiency of four chloroplast genes were markly altered. Compared with WT, las1 exhibited defective in biogenesis of chloroplast ribosomes.

Conclusions

Our results show that LAS1/OsHMBPP plays an essential role in the early chloroplast development in rice.

中文翻译：

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水稻叶绿体靶向基因OsHMBPP的破坏会导致幼苗致命的白化病表型。

背景

叶绿体的发育受质体和核编码基因的协调调节。尽管据报道许多调节剂参与叶绿体的发育，但鉴于这一过程的复杂性，仍有待确定新的因素。

结果

在这项研究中，我们表征了靶向叶绿体的水稻突变体致死性白化病幼苗1（las1）形式的4-羟基-3-甲基丁-2-烯基二磷酸还原酶（OsHMBPP）。该LAS1突变引起幼苗白化致死表型。透射电子显微镜表明，las1在早期叶绿体发育中是有缺陷的。LAS1在叶子中优先表达，这暗示其在控制叶绿体发育中的作用。las1中许多叶绿体编码基因的表达水平发生了显着变化。las1中参与Chl生物合成的核编码基因的表达水平也降低了。我们进一步研究了las1中质体RNA的编辑，发现四个叶绿体基因的编辑效率发生了明显变化。与野生型相比，las1在叶绿体核糖体的生物发生中表现出缺陷。

结论

我们的结果表明，LAS1 / OsHMBPP在水稻的早期叶绿体发育中起着至关重要的作用。