NIMA-related kinase NEK6 affects plant growth and stress response in Arabidopsis

Abstract

The NIMA-related kinases (NEKs) are a family of serine/threonine kinases involved largely in cell cycle controlin fungi, mammals and other eukaryotes. In Arabidopsis, NEK6 is involved in the regulation of epidermal cellmorphogenesis. However, other roles of NEK6 in plants are less well understood. Here we report functions ofNEK6 in plant growth, development and stress responses in Arabidopsis. NEK6 transcripts and proteins areinduced by ethylene precursor ACC and salt stress. Expression of other NEK genes except NEK5 is alsoresponsive to the two treatments. Overexpression and mutant analysis disclose that the NEK6 gene increasesrosette growth, seed yield and lateral root formation. However, NEK6 appears to play a negative role in thecontrol of seed size. The gene also promotes plant tolerance to salt stress and osmotic stress in itsoverexpressing plants. The NEK6 gene may achieve its function through suppression of ethylene biosynthesisand activation of CYCB1;1 and CYCA3;1 expression. Our present study reveals new functions of the NEK6 genein plant growth and stress tolerance, and manipulation of NEK6 may improve important agronomic traits incrop plants.