Identification of Potato StPIN Gene Family and Regulation of Root Development by StPIN4

The growth hormone export PIN-FORMED (PIN) is an important carrier for regulating the polar transport of plant growth hormones and plays an important role in plant growth and development. However, little is known about the characteristics and functions of PINs in potatoes. In this study, 10 <i>PIN</i> members were identified from potatoes and named <i>StPIN1</i>, <i>StPIN2</i>, <i>StPIN3</i>, <i>StPIN4</i>, <i>StPIN5</i>, <i>StPIN6</i>, <i>StPIN7</i>, <i>StPIN8</i>, <i>StPIN9</i>, and <i>StPIN10</i> according to their positions in the potato chromosome In addition, the expression of 10 <i>StPINs</i> was analyzed by qRT-PCR during potato root development. The results showed that the <i>StPIN4</i> gene plays an important regulatory role in potato root development, and its tissue expression varied greatly. Several <i>cis</i>-regulatory elements related to growth factors were also detected in the promoter region of the <i>StPIN</i> gene. The transgenic overexpressing <i>StPIN4</i> in potato showed suppressed growth in root length and lateral root number, and <i>StPIN4</i>-interfering plants showed the opposite. These results suggested that <i>StPIN4</i> plays a key role in the regulation of the potato root architecture.