Oil Crops Research Institute of the Chinese Academy of Agricultural Sciences, Key Laboratory of Biology and Genetic Improvement of Oil Crops of the Ministry of Agriculture, Wuhan, 430062, China.
Centre d'Etudes Régional pour l'Amélioration de l'Adaptation à la Sécheresse (CERAAS), Route de Khombole, BP 3320, Thiès, Sénégal.
BMC Genet. 2019 May 16;20(1):45. doi: 10.1186/s12863-019-0747-7.
Sesame (Sesamum indicum) can accumulate over 60% oil in its seed. However, low oil content genotypes with an oil content of less than 50% are also observed. To gain insights into how genes shape this variation, we examined 22 seed and carpel transcriptomes from 3 varieties of sesame with high and low oil content.
A total of 34.6~52.2% of the sesame genes were expressed with a RPKM greater than 5 in the 22 tissue samples. The expressed gene numbers tended to decrease in the seed but fluctuated in the carpels from 10 to 30 days post-anthesis (DPA). Compared with that of the low oil content sesames, the high oil content sesame exhibited more positive gene expression during seed development. Typically, genes involved in lipid biosynthesis were enriched and could distinguish the high and low genotypes at 30 DPA, suggesting the pivotal role of seed oil biosynthesis in the later stages. Key homologous lipid genes that function in TAG biosynthesis, including those that encoded glycerol-3-phosphate acyltransferase (GPAT), acyl-CoA:diacylglycerol acyltransferase (DGAT), and phospholipid:diacylglycerol acyltransferase (PDAT), were strengthened asynchronously at different stages, but the lipid transfer protein (LTP)-encoding genes, including SIN_1019175, SIN_1019172 and SIN_1010009, usually were highlighted in the high oil content sesames. Furthermore, a list of 23 candidate genes was identified and predicted to be beneficial for higher oil content accumulation. Despite the different gene expression patterns between the seeds and carpels, the two tissues showed a cooperative relationship during seed development, and biological processes, such as transport, catabolic process and small molecule metabolic process, changed synchronously.
The study elucidated the different expression profiles in high and low oil content sesames and revealed key stages and a list of candidate genes that shaped oil content variation. These findings will accelerate dissection of the genetic mechanism of sesame oil biosynthesis.
芝麻（Sesamum indicum）的种子可以积累超过 60%的油。然而，也观察到含油量低于 50%的低油含量基因型。为了深入了解基因如何塑造这种变化，我们检查了 3 种高油和低油含量芝麻品种的 22 个种子和心皮转录组。
在 22 个组织样本中，共有 34.6%至 52.2%的芝麻基因的 RPKM 值大于 5。在种子中，表达基因的数量往往会减少，但在授粉后 10 至 30 天（DPA）的心皮中波动。与低油含量的芝麻相比，高油含量的芝麻在种子发育过程中表现出更多的正基因表达。通常，与脂质生物合成相关的基因被富集，并且可以在 30 DPA 时区分高和低基因型，表明种子油生物合成在后期阶段的关键作用。在 TAG 生物合成中起作用的关键同源脂质基因，包括编码甘油-3-磷酸酰基转移酶（GPAT）、酰基辅酶 A：二酰甘油酰基转移酶（DGAT）和磷脂：二酰甘油酰基转移酶（PDAT）的基因，在不同阶段被异步加强，但脂质转移蛋白（LTP）编码基因，包括 SIN_1019175、SIN_1019172 和 SIN_1010009，通常在高油含量的芝麻中突出。此外，鉴定并预测了 23 个候选基因，这些基因可能有利于更高的油含量积累。尽管种子和心皮之间的基因表达模式不同，但在种子发育过程中，这两种组织表现出协同关系，并且生物过程，如运输、分解代谢过程和小分子代谢过程，同步变化。
该研究阐明了高油和低油含量芝麻中的不同表达谱，并揭示了塑造油含量变化的关键阶段和一组候选基因。这些发现将加速芝麻油生物合成遗传机制的解析。
