Background

Carotenoid biosynthesis is essential for the generation of photosynthetic pigments, phytohormone production, and flower color development. The light harvesting like 3 (LIL3) protein, which belongs to the light-harvesting complex protein family in photosystems, interacts with geranylgeranyl reductase (GGR) and protochlorophyllide oxidoreductase (POR) both of which are known to regulate terpenoid and chlorophyll biosynthesis, respectively, in both rice and Arabidopsis.

Results

In our study, a CRISPR-Cas9 generated 4-bp deletion mutant oslil3 showed aberrant chloroplast development, growth defects, low fertility rates and reduced pigment contents. A comparative transcriptomic analysis of oslil3 suggested that differentially expressed genes (DEGs) involved in photosynthesis, cell wall modification, primary and secondary metabolism are differentially regulated in the mutant. Protein-protein interaction assays indicated that LIL3 interacts with phytoene synthase (PSY) and in addition the gene expression of PSY genes are regulated by LIL3. Subcellular localization of LIL3 and PSY suggested that both are thylakoid membrane anchored proteins in the chloroplast. We suggest that LIL3 directly interacts with PSY to regulate carotenoid biosynthesis.

Conclusion

This study reveals a new role of LIL3 in regulating pigment biosynthesis through interaction with the rate limiting enzyme PSY in carotenoid biosynthesis in rice presenting it as a putative target for genetic manipulation of pigment biosynthesis pathways in crop plants.

中文翻译：

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捕光样蛋白 3 与八氢番茄红素合酶相互作用，是水稻类胡萝卜素和叶绿素生物合成所必需的

背景

类胡萝卜素生物合成对于光合色素的产生、植物激素的产生和花色发育至关重要。光捕获样 3 (LIL3) 蛋白属于光系统中光捕获复合蛋白家族，与已知分别调节萜类化合物和叶绿素生物合成的香叶基香叶基还原酶 (GGR) 和原叶绿素氧化还原酶 (POR) 相互作用，在水稻和拟南芥中。

结果

在我们的研究中，CRISPR-Cas9 产生的 4-bp 缺失突变体oslil3表现出异常的叶绿体发育、生长缺陷、低生育率和色素含量降低。oslil3 的比较转录组学分析表明，参与光合作用、细胞壁修饰、初级和次级代谢的差异表达基因 (DEG) 在突变体中受到差异调节。蛋白质-蛋白质相互作用测定表明 LIL3 与八氢番茄红素合酶 (PSY) 相互作用，此外PSY基因的基因表达受LIL3调节. LIL3 和 PSY 的亚细胞定位表明两者都是叶绿体中的类囊体膜锚定蛋白。我们建议 LIL3 直接与 PSY 相互作用以调节类胡萝卜素的生物合成。

结论

该研究揭示了 LIL3 通过与水稻类胡萝卜素生物合成中的限速酶 PSY 相互作用，在调节色素生物合成中的新作用，将其作为作物植物色素生物合成途径遗传操作的推定靶标。