AUTHOR=Mao Yunfei , Yin Yijun , Cui Xueli , Wang Haiyan , Su XiaFei , Qin Xin , Liu Yangbo , Hu Yanli , Shen Xiang 

TITLE=Homologous Cloning of Potassium Channel Genes From the Superior Apple Rootstock Line 12-2, Which is Tolerant to Apple Replant Disease

JOURNAL=Frontiers in Genetics

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/genetics/articles/10.3389/fgene.2022.803160

DOI=10.3389/fgene.2022.803160

ISSN=1664-8021

ABSTRACT=<p>Potassium channels are important ion channels that are responsible for the absorption of potassium in the plant nutrient uptake system. In this study, we used homologous molecular cloning to obtain 8 K<sup>+</sup> channel genes from the superior apple rootstock line 12-2 (self-named): <italic>MsAKT1-1</italic>, <italic>MsKAT3-2</italic>, <italic>MsKAT1-3</italic>, <italic>MsK2P3-4</italic>, <italic>MsK2P3-5</italic>, <italic>MsK2P5-6</italic>, <italic>MsK2P3-7</italic>, and <italic>MsK2P3-8</italic>. Their lengths varied from 942 bp (<italic>MsK2P5-6</italic>) to 2625 bp (<italic>MsAKT1-1</italic>), and the number of encoded amino acids varied from 314 (<italic>MsK2P5-6</italic>) to 874 (<italic>MsAKT1-1</italic>). Subcellular localization predictions showed that <italic>MsAKT1-1</italic>, <italic>MsKAT3-2</italic>, and <italic>MsKAT1-3</italic> were localized on the plasma membrane, and <italic>MsK2P3-4</italic>, <italic>MsK2P3-5</italic>, <italic>MsK2P5-6</italic>, <italic>MsK2P3-7</italic>, and <italic>MsK2P3-8</italic> were localized on the vacuole and plasma membrane. The 8 K<sup>+</sup> channel proteins contained α helices, extended strands, β turns, and random coils. <italic>MsKAT1-3</italic> had four transmembrane structures, <italic>MsKAT3-2</italic> had six, and the other six K<sup>+</sup> channel genes had five. Protein structure domain analysis showed that <italic>MsAKT1-1</italic> contained nine protein domains, followed by <italic>MsKAT3-2</italic> with four, <italic>MsKAT1-3</italic> with three, and the other five two-pore domain K<sup>+</sup> channel proteins with two. Semi-quantitative RT-PCR detection of the K<sup>+</sup> channel genes showed that their expression levels were high in roots. qRT-PCR analysis showed that the relative expression levels of the 8 genes changed after exposure to ARD stress. The above results provide a theoretical basis for further research on the functions of potassium channel genes in 12-2 and a scientific basis for the breeding of ARD-resistant rootstock.</p>