Li Jiyu, Liu Chunyan, Yu Qing, Cao Zhen, Yang Yuan, Jia Botao, Su Ying, Li Guixiang, Qin Gaihua
Key Laboratory of Horticultural Crop Genetic Improvement and Eco-Physiology of Anhui Province, Institute of Horticulture Research, Anhui Academy of Agricultural Sciences, Hefei, 230031 China.
Key Laboratory of Fruit Quality and Developmental Biology, Anhui Academy of Agricultural Sciences, Hefei, 230031 China.
3 Biotech. 2022 Sep;12(9):181. doi: 10.1007/s13205-022-03248-6. Epub 2022 Jul 19.
Sugar content of the outer seed coat and hardness of the inner seed coat are important traits of the pomegranate fruit. The translocation of sugars across biological membranes, mediated by SWEET transporters, is critical to seed development. In this study, we identified 16 PgrSWEET genes distributed on six chromosomes in the pomegranate genome. According to the phylogenetic analysis, PgrSWEET proteins were divided into four groups. Tandem and segmental duplications contributed to the expansion of the PgrSWEET family, while functional redundancy and diversification may have occurred among SWEET members according to analyses of evolution and gene expression. RNA-seq and qRT-PCR analyses revealed that PgrSWEET1a and PgrSWEET9 were highly expressed in the inner seed coat, and the expression levels gradually increased during seed development. Moreover, the relative expression levels of PgrSWEET1a and PgrSWEET9 in a hard-seeded cultivar were higher than those in a soft-seeded cultivar, indicating that PgrSWEET1a and PgrSWEET9 might function in the inner seed coat development by accumulating sugar metabolites. We also found that PgrSWEET2 was highly expressed in the outer seed coat during seed development, and the protein was localized to the tonoplast, indicating that PgrSWEET2 is likely a candidate regulating sugar accumulation or reutilization in the vacuoles of the outer seed coat. Genes encoding transcription factors probably regulating the candidate PgrSWEET genes were chosen by co-expression analysis. These results not only helped to characterize PgrSWEET genes but also provided an insight into their functions in relation to seed coat development.
The online version contains supplementary material available at 10.1007/s13205-022-03248-6.
石榴果实外种皮的含糖量和内种皮的硬度是重要性状。由SWEET转运蛋白介导的糖类跨生物膜转运对种子发育至关重要。在本研究中，我们在石榴基因组中鉴定出16个PgrSWEET基因，分布在6条染色体上。根据系统发育分析，PgrSWEET蛋白分为4组。串联重复和片段重复导致了PgrSWEET家族的扩张，而根据进化和基因表达分析，SWEET成员之间可能发生了功能冗余和多样化。RNA测序和定量逆转录聚合酶链反应分析表明，PgrSWEET1a和PgrSWEET9在内种皮中高表达，且在种子发育过程中表达水平逐渐升高。此外，硬籽品种中PgrSWEET1a和PgrSWEET9的相对表达水平高于软籽品种，表明PgrSWEET1a和PgrSWEET9可能通过积累糖类代谢产物在内种皮发育中发挥作用。我们还发现，PgrSWEET2在种子发育过程中外种皮中高表达，且该蛋白定位于液泡膜，表明PgrSWEET2可能是调节外种皮液泡中糖类积累或再利用的候选基因。通过共表达分析选择了可能调控候选PgrSWEET基因的转录因子编码基因。这些结果不仅有助于表征PgrSWEET基因，还为深入了解它们在种皮发育中的功能提供了思路。
在线版本包含可在10.1007/s13205-022-03248-6获取的补充材料。
