Institute of Animal Science, Chinese Academy of Agricultural Sciences, 100193, Beijing, China.
West Arid Region Grassland Resource and Ecology Key Laboratory, College of Grassland and Environmental Sciences, Xinjiang Agricultural University, 830052, Urumqi, China.
BMC Genomics. 2022 Dec 1;23(1):791. doi: 10.1186/s12864-022-09009-2.
The high-affinity K transporter (HAK) family plays a vital role in K uptake and transport as well as in salt and drought stress responses. In the present study, we identified 22 HAK genes in each Medicago truncatula and Medicago sativa genome. Phylogenetic analysis suggested that these HAK proteins could be divided into four clades, and the members of the same subgroup share similar gene structure and conserved motifs. Many cis-acting elements related with defense and stress were found in their promoter region. In addition, gene expression profiles analyzed with genechip and transcriptome data showed that these HAK genes exhibited distinct expression pattern in different tissues, and in response to salt and drought treatments. Furthermore, co-expression analysis showed that 6 homologous HAK hub gene pairs involved in direct network interactions. RT-qPCR verified that the expression level of six HAK gene pairs was induced by NaCl and mannitol treatment to different extents. In particular, MtHK2/7/12 from M. truncatula and MsHAK2/6/7 from M. sativa were highly induced. The expression level of MsHAK1/2/11 determined by RT-qPCR showed significantly positive correlation with transcriptome data. In conclusion, our study shows that HAK genes play a key role in response to various abiotic stresses in Medicago, and the highly inducible candidate HAK genes could be used for further functional studies and molecular breeding in Medicago.
高亲和力 K 转运体（HAK）家族在 K 吸收和转运以及盐和干旱胁迫反应中发挥着重要作用。在本研究中，我们在每个蒺藜苜蓿和紫花苜蓿基因组中鉴定了 22 个 HAK 基因。系统发育分析表明，这些 HAK 蛋白可以分为四个分支，同一亚组的成员具有相似的基因结构和保守基序。在启动子区域发现了许多与防御和应激相关的顺式作用元件。此外，利用基因芯片和转录组数据进行的基因表达谱分析表明，这些 HAK 基因在不同组织中表现出不同的表达模式，并对盐和干旱处理有反应。此外，共表达分析表明，6 对同源 HAK 枢纽基因对参与直接网络相互作用。RT-qPCR 验证了 6 对 HAK 基因对在 NaCl 和甘露醇处理下的表达水平被不同程度地诱导。特别是，来自蒺藜苜蓿的 MtHK2/7/12 和来自紫花苜蓿的 MsHAK2/6/7 被高度诱导。通过 RT-qPCR 确定的 MsHAK1/2/11 的表达水平与转录组数据显示出显著的正相关。总之，我们的研究表明，HAK 基因在蒺藜苜蓿响应各种非生物胁迫中起着关键作用，高度诱导的候选 HAK 基因可用于进一步的功能研究和蒺藜苜蓿的分子育种。
