National Key Laboratory for Tropical Crop Breeding/Hainan Key Laboratory for Biosafety Monitoring and Molecular Breeding in Off-Season Reproduction Regions, Institute of Tropical Biosciences and Biotechnology/Sanya Research Institute of Chinese Academy of Tropical Agricultural Sciences, Haikou, Hainan, 571101, P. R. China.
Hubei Provincial Key Laboratory for Protection and Application of Special Plants in Wuling Area of China, College of Life Science, South-Central Minzu University, Wuhan, Hubei, 430074, P. R. China.
BMC Plant Biol. 2024 Apr 18;24(1):298. doi: 10.1186/s12870-024-04969-x.
Tonoplast intrinsic proteins (TIPs), which typically mediate water transport across vacuolar membranes, play an essential role in plant growth, development, and stress responses. However, their characterization in tigernut (Cyperus esculentus L.), an oil-bearing tuber plant of the Cyperaceae family, is still in the infancy.
In this study, a first genome-wide characterization of the TIP subfamily was conducted in tigernut, resulting in ten members representing five previously defined phylogenetic groups, i.e., TIP1-5. Although the gene amounts are equal to that present in two model plants Arabidopsis and rice, the group composition and/or evolution pattern were shown to be different. Except for CeTIP1;3 that has no counterpart in both Arabidopsis and rice, complex orthologous relationships of 1:1, 1:2, 1:3, 2:1, and 2:2 were observed. Expansion of the CeTIP subfamily was contributed by whole-genome duplication (WGD), transposed, and dispersed duplications. In contrast to the recent WGD-derivation of CeTIP3;1/-3;2, synteny analyses indicated that TIP4 and - 5 are old WGD repeats of TIP2, appearing sometime before monocot-eudicot divergence. Expression analysis revealed that CeTIP genes exhibit diverse expression profiles and are subjected to developmental and diurnal fluctuation regulation. Moreover, when transiently overexpressed in tobacco leaves, CeTIP1;1 was shown to locate in the vacuolar membrane and function in homo/heteromultimer, whereas CeTIP2;1 is located in the cell membrane and only function in heteromultimer. Interestingly, CeTIP1;1 could mediate the tonoplast-localization of CeTIP2;1 via protein interaction, implying complex regulatory patterns.
Our findings provide a global view of CeTIP genes, which provide valuable information for further functional analysis and genetic improvement through manipulating key members in tigernut.
液泡膜内在蛋白（TIPs）通常介导水跨液泡膜的运输，在植物生长、发育和应激反应中起着重要作用。然而，在 Cyperaceae 科的油薯（Cyperus esculentus L.）中，其 TIP 的特征仍然处于起步阶段。
本研究首次对油薯中的 TIP 亚家族进行了全基因组特征分析，得到了代表五个先前定义的系统发育群的 10 个成员，即 TIP1-5。尽管基因数量与拟南芥和水稻中的数量相同，但组成和/或进化模式表明存在差异。除了 CeTIP1;3 在拟南芥和水稻中都没有对应物外，还观察到了 1:1、1:2、1:3、2:1 和 2:2 的复杂直系同源关系。CeTIP 亚家族的扩张是由全基因组复制（WGD）、转座和分散重复产生的。与 CeTIP3;1/-3;2 的最近 WGD 衍生不同，同线性分析表明 TIP4 和 -5 是 TIP2 的古老 WGD 重复，出现在单子叶植物和双子叶植物分化之前。表达分析表明，CeTIP 基因表现出不同的表达谱，并受到发育和昼夜波动调节。此外，当在烟草叶片中瞬时过表达时，CeTIP1;1 被证明定位于液泡膜，并在同源/异源三聚体中发挥作用，而 CeTIP2;1 定位于细胞膜，仅在异源三聚体中发挥作用。有趣的是，CeTIP1;1 可以通过蛋白相互作用介导 CeTIP2;1 的液泡定位，暗示存在复杂的调控模式。
我们的研究结果提供了 CeTIP 基因的全局视图，为进一步通过操纵油薯中的关键成员进行功能分析和遗传改良提供了有价值的信息。
