The Role of Chloroplast Gene Expression in Plant Growth and Development

叶绿体在植物代谢和支持植物细胞的生长和分化中起着核心作用。 虽然大多数叶绿体蛋白质在细胞核中编码，在细胞质中产生，并输入到叶绿体中，但很少由叶绿体基因组编码。 通常，干扰叶绿体基因功能会导致光合作用的缺陷，但在某些物种中，这种干扰的影响更为严重，并导致早期死亡。 例如，在拟南芥中破坏叶绿体翻译通常会导致胚胎死亡，但在其他物种中，结果是白化病，但可行的幼苗。 最近的工作表明，一个单一的叶绿体基因（accD），编码一个亚基的异聚体乙酰辅酶A羧化酶所需的脂肪酸的生物合成，可能是负责惊人的不同的后果-致死性与可行的白化病-在不同的植物物种中阻止叶绿体翻译。 该项目将评估这一模型，探索其对植物生物学的影响，并提供有价值的见解，植物发育的基础细胞和代谢过程。 将采用几种不同的策略：（1）确定叶绿体翻译缺陷的拟南芥突变体的胚胎致死性是否可以通过编码通常胞质同质羧化酶的叶绿体定位版本的核转基因来拯救;（2）比较破坏的后果不同品种的拟南芥中的叶绿体翻译;和（3）评价其中accD已经从叶绿体基因组中丢失的植物谱系。这项工作将有助于说明在不同植物物种中破坏编码相同代谢功能的基因如何产生不同的发育影响。 研究结果将发表在科学期刊上，生物材料将分发到拟南芥储备中心。 基于这项研究的暑期实验室课程将被开发，以纳入植物遗传学，生物化学和进化的原则，提供生物学专业的另一种方式，以满足实验室的要求，专注于增强研究，分析和写作技能。

Chloroplasts play a central role in plant metabolism and in supporting the growth and differentiation of plant cells. Although most chloroplast proteins are encoded in the nucleus, produced in the cytosol, and imported into the chloroplast, few are encoded by the chloroplast genome. Typically, interfering with chloroplast gene function causes defects in photosynthesis, but in some species the effects of such disruptions are more severe and result in early lethality. For example, disrupting chloroplast translation in Arabidopsis often causes embryo lethality, but in other species results in seedlings that are albino, but viable. Recent work suggests that a single chloroplast gene (accD), encoding one subunit of a heteromeric acetyl-CoA carboxylase required for fatty acid biosynthesis, may be responsible for the strikingly different consequences - lethality vs. viable albino - of blocking chloroplast translation in different plant species. This project will evaluate this model, explore its implications for plant biology, and provide valuable insights into basic cellular and metabolic processes that underlie plant development. Several different strategies will be pursued: (1) Determine whether embryo lethality in Arabidopsis mutants defective in chloroplast translation can be rescued by a nuclear transgene encoding a chloroplast-localized version of the normally cytosolic, homomeric carboxylase; (2) Compare the consequences of disrupting chloroplast translation in different accessions of Arabidopsis; and (3) Evaluate plant lineages where accD has been lost from the chloroplast genome. This work will help to illustrate how disrupting genes encoding the same metabolic function in different plant species can have divergent developmental impacts. Results will be published in scientific journals and biological materials distributed to Arabidopsis stock centers. A summer lab course based on this research will be developed to incorporate principles of plant genetics, biochemistry, and evolution, offering biology majors an alternative way to meet lab requirements by focusing on enhanced research, analytical, and writing skills.