College of Horticulture and Landscape Architecture, Northeast Agricultural University, Harbin, Heilongjiang, 150006, China.
Key Laboratory of Biology and Genetic Improvement of Horticulture Crops (Northeast Region), Ministry of Agriculture and Rural Affairs, Harbin, Heilongjiang, 150006, China.
BMC Genomics. 2024 Sep 5;25(1):836. doi: 10.1186/s12864-024-10712-5.
The KT/HAK/KUP is the largest K transporter family in plants, playing crucial roles in K absorption, transport, and defense against environmental stress. Sweet watermelon is an economically significant horticultural crop belonging to the genus Citrullus, with a high demand for K during its growth process. However, a comprehensive analysis of the KT/HAK/KUP gene family in watermelon has not been reported.
14 KT/HAK/KUP genes were identified in the genomes of each of seven Citrullus species. These KT/HAK/KUPs in watermelon were unevenly distributed across seven chromosomes. Segmental duplication is the primary driving force behind the expansion of the KT/HAK/KUP family, subjected to purifying selection during domestication (Ka/Ks < 1), and all KT/HAK/KUPs exhibit conserved motifs and could be phylogenetically classified into four groups. The promoters of KT/HAK/KUPs contain numerous cis-regulatory elements related to plant growth and development, phytohormone response, and stress response. Under K deficiency, the growth of watermelon seedlings was significantly inhibited, with cultivated watermelon experiencing greater impacts (canopy width, redox enzyme activity) compared to the wild type. All KT/HAK/KUPs in C. lanatus and C. amarus exhibit specific expression responses to K-deficiency and drought stress by qRT-PCR. Notably, ClG42_07g0120700/CaPI482276_07g014010 were predominantly expressed in roots and were further induced by K-deficiency and drought stress. Additionally, the K transport capacity of ClG42_07g0120700 under low K stress was confirmed by yeast functional complementation assay.
KT/HAK/KUP genes in watermelon were systematically identified and analyzed at the pangenome level and provide a foundation for understanding the classification and functions of the KT/HAK/KUPs in watermelon plants.
KT/HAK/KUP 是植物中最大的 K 转运蛋白家族，在 K 的吸收、运输和抵御环境胁迫方面发挥着关键作用。甜西瓜是一种经济意义重大的园艺作物，属于葫芦属，在生长过程中对 K 的需求量很大。然而，尚未有关于西瓜 KT/HAK/KUP 基因家族的全面分析。
在 7 个甜瓜属物种的基因组中分别鉴定出 14 个 KT/HAK/KUP 基因。这些西瓜中的 KT/HAK/KUP 不均匀分布在 7 条染色体上。片段重复是 KT/HAK/KUP 家族扩张的主要驱动力，在驯化过程中受到纯化选择（Ka/Ks<1），所有 KT/HAK/KUP 都具有保守的基序，可以通过系统发育分类为四个组。KT/HAK/KUP 的启动子包含许多与植物生长发育、植物激素响应和应激响应相关的顺式调控元件。在 K 缺乏的情况下，西瓜幼苗的生长受到显著抑制，与野生型相比，栽培西瓜受到的影响更大（冠层宽度、氧化还原酶活性）。通过 qRT-PCR，C. lanatus 和 C. amarus 中的所有 KT/HAK/KUP 对 K 缺乏和干旱胁迫均表现出特定的表达响应。值得注意的是，ClG42_07g0120700/CaPI482276_07g014010 在根中主要表达，并进一步受到 K 缺乏和干旱胁迫的诱导。此外，通过酵母功能互补测定证实了 ClG42_07g0120700 在低钾胁迫下的 K 转运能力。
在泛基因组水平上系统地鉴定和分析了西瓜中的 KT/HAK/KUP 基因，为了解西瓜植物 KT/HAK/KUP 的分类和功能提供了基础。
