López-Ribera Ignacio, La Paz José Luis, Repiso Carlos, García Nora, Miquel Mercè, Hernández María Luisa, Martínez-Rivas José Manuel, Vicient Carlos M
Department of Molecular Genetics, Centre for Research in Agricultural Genomics , 08193 Barcelona, Spain.
Plant Physiol. 2014 Mar;164(3):1237-49. doi: 10.1104/pp.113.233221. Epub 2014 Jan 9.
A transcriptomic approach has been used to identify genes predominantly expressed in maize (Zea mays) scutellum during maturation. One of the identified genes is oil body associated protein1 (obap1), which is transcribed during seed maturation predominantly in the scutellum, and its expression decreases rapidly after germination. Proteins similar to OBAP1 are present in all plants, including primitive plants and mosses, and in some fungi and bacteria. In plants, obap genes are divided in two subfamilies. Arabidopsis (Arabidopsis thaliana) genome contains five genes coding for OBAP proteins. Arabidopsis OBAP1a protein is accumulated during seed maturation and disappears after germination. Agroinfiltration of tobacco (Nicotiana benthamiana) epidermal leaf cells with fusions of OBAP1 to yellow fluorescent protein and immunogold labeling of embryo transmission electron microscopy sections showed that OBAP1 protein is mainly localized in the surface of the oil bodies. OBAP1 protein was detected in the oil body cellular fraction of Arabidopsis embryos. Deletion analyses demonstrate that the most hydrophilic part of the protein is responsible for the oil body localization, which suggests an indirect interaction of OBAP1 with other proteins in the oil body surface. An Arabidopsis mutant with a transfer DNA inserted in the second exon of the obap1a gene and an RNA interference line against the same gene showed a decrease in the germination rate, a decrease in seed oil content, and changes in fatty acid composition, and their embryos have few, big, and irregular oil bodies compared with the wild type. Taken together, our findings suggest that OBAP1 protein is involved in the stability of oil bodies.
一种转录组学方法已被用于鉴定在玉米（Zea mays）成熟胚盾片中主要表达的基因。其中一个被鉴定的基因是油体相关蛋白1（obap1），它在种子成熟过程中主要在胚盾片中转录，并且其表达在萌发后迅速下降。与OBAP1相似的蛋白质存在于所有植物中，包括原始植物和苔藓，以及一些真菌和细菌中。在植物中，obap基因分为两个亚家族。拟南芥（Arabidopsis thaliana）基因组包含五个编码OBAP蛋白的基因。拟南芥OBAP1a蛋白在种子成熟过程中积累，并在萌发后消失。用OBAP1与黄色荧光蛋白的融合体对烟草（Nicotiana benthamiana）表皮叶细胞进行农杆菌浸润，并对胚胎透射电子显微镜切片进行免疫金标记，结果表明OBAP1蛋白主要定位于油体表面。在拟南芥胚胎的油体细胞组分中检测到了OBAP1蛋白。缺失分析表明，该蛋白最亲水的部分负责油体定位，这表明OBAP1与油体表面的其他蛋白存在间接相互作用。一个在obap1a基因的第二个外显子中插入转移DNA的拟南芥突变体和一个针对同一基因的RNA干扰株系，其萌发率降低，种子油含量降低，脂肪酸组成发生变化，与野生型相比，它们的胚胎有很少、很大且不规则的油体。综上所述，我们的研究结果表明OBAP1蛋白参与了油体的稳定性。
