Functional analysis of <italic>StMAPK4</italic> in response to low temperature stress in potato

Abstract

<p id="C3">Potato is vulnerable to low temperatures resulting in reduced yield production. <italic>MAPK</italic> gene is widely involved in a variety of environmental stress, and it has been detected to be involved in low temperature regulation. In this present study, to explore <italic>StMAPK4</italic> function in response to low temperature stress, potato cultivar ‘Atlantic’ as the experimental material, the expression characteristics of <italic>StMAPK4</italic> gene were analyzed in potato root, stem, and leaf at the different time under low temperature (4℃) stress. <italic>StMAPK4</italic> gene was analyzed using bioinformatics and its encoded protein subcellular localization was assayed. <italic>StMAPK4</italic> overexpression and RNA interference expression vectors were constructed and obtained transgenic potato plants. The activities of superoxide dismutase (SOD) and peroxidase (POD), and the contents of proline (Pro) and malondialdehyde (MDA) in non-transgenic (NT), overexpressed and RNAi interfered transgenic plants were analyzed under 4℃. The results showed that the isoelectric point (pI) of StMAPK4 was 4.97 and it was acidic protein localized in the nucleus and cell membrane. The relative expression levels of <italic>StMAPK4</italic> in roots, stems, and leaves significantly increased under low temperature stress. Compared with non-transgenic plants, the activities of SOD and POD and the content of proline in <italic>StMAPK4</italic> overexpressed plants were significantly increased, while the content of MDA was significantly decreased. Compared with NT plants, the activities of SOD and POD, and the content of Pro in <italic>StMAPK4</italic> overexpression plants were significantly decreased, while the content of MDA was significantly increased. Phenotypic observation revealed that the leaves of non-transgenic and RNAi interfered expression plants wilted seriously, while the leaves of overexpressed plants were less affected. In summary, the overexpression of <italic>StMAPK4</italic> gene can enhance the tolerance of low temperature stress in potato plants.