Jiangxi Key Laboratory for Postharvest Technology and Nondestructive Testing of Fruits and Vegetables, Collaborative Innovation Center of Postharvest Key Technology and Quality Safety of Fruits and Vegetables, Jiangxi Agricultural University, Nanchang, 330045, China.
College of Materials and Chemical Engineering, Pingxiang University, Pingxiang, 330075, China.
BMC Plant Biol. 2022 Mar 9;22(1):108. doi: 10.1186/s12870-022-03498-9.
Potassium (K) is important in the regulation of plant growth and development. It is the most abundant mineral element in kiwifruit, and its content increases during fruit ripening. However, how K transporter works in kiwifruit postharvest maturation is not yet clear.
Here, 12 K transporter KT/HAK/KUP genes, AcKUP1 ~ AcKUP12, were isolated from kiwifruit, and their phylogeny, genomic structure, chromosomal location, protein properties, conserved motifs and cis-acting elements were analysed. Transcription analysis revealed that AcKUP2 expression increased rapidly and was maintained at a high level during postharvest maturation, consistent with the trend of K content; AcKUP2 expression was induced by ethylene, suggesting that AcKUP2 might play a role in ripening. Fluorescence microscopy showed that AcKUP2 is localised in the plasma membrane. Cis-elements, including DER or ethylene response element (ERE) responsive to ethylene, were found in the AcKUP2 promoter sequence, and ethylene significantly enhanced the AcKUP2 promoter activity. Furthermore, we verified that AcERF15, an ethylene response factor, directly binds to the AcKUP2 promoter to promote its expression. Thus, AcKUP2 may be an important potassium transporter gene which involved in ethylene-regulated kiwifruit postharvest ripening.
Therefore, our study establishes the first genome-wide analysis of the kiwifruit KT/HAK/KUP gene family and provides valuable information for understanding the function of the KT/HAK/KUP genes in kiwifruit postharvest ripening.
钾（K）在植物生长和发育的调节中很重要。它是猕猴桃中最丰富的矿物质元素，其含量在果实成熟过程中增加。然而，K 转运体在猕猴桃采后成熟过程中是如何工作的还不清楚。
本研究从猕猴桃中分离得到 12 个 K 转运体 KT/HAK/KUP 基因，即 AcKUP1~AcKUP12，并对其系统发育、基因组结构、染色体定位、蛋白特性、保守基序和顺式作用元件进行了分析。转录分析表明，AcKUP2 在采后成熟过程中迅速表达并保持高水平，与 K 含量的趋势一致；AcKUP2 的表达受乙烯诱导，表明 AcKUP2 可能在成熟过程中发挥作用。荧光显微镜显示 AcKUP2 定位于质膜。AcKUP2 启动子序列中存在 DRE 或对乙烯响应的 ERE 等顺式元件，乙烯显著增强了 AcKUP2 启动子的活性。此外，我们验证了乙烯响应因子 AcERF15 直接结合 AcKUP2 启动子促进其表达。因此，AcKUP2 可能是一个参与乙烯调控猕猴桃采后成熟的重要钾转运体基因。
因此，本研究首次对猕猴桃 KT/HAK/KUP 基因家族进行了全基因组分析，为了解 KT/HAK/KUP 基因在猕猴桃采后成熟过程中的功能提供了有价值的信息。
