A leu-rich repeat receptor-like protein kinase, FaRIPK1, interacts with the ABA receptor, FaABAR, to regulate fruit ripening in strawberry

J Exp Bot. 2018 Mar 24;69(7):1569-1582. doi: 10.1093/jxb/erx488.

Abstract

Strawberry (Fragaria×ananassa) is a model plant for studying non-climacteric fruit ripening regulated by abscisic acid (ABA); however, its exact molecular mechanisms are yet not fully understood. In this study, a predicted leu-rich repeat (LRR) receptor-like kinase in strawberry, red-initial protein kinase 1 (FaRIPK1), was screened and, using a yeast two-hybrid assay, was shown to interact with a putative ABA receptor, FaABAR. This association was confirmed by bimolecular fluorescence complementation and co-immunoprecipitation assays, and shown to occur in the nucleus. Expression analysis by real-time PCR showed that FaRIPK1 is expressed in roots, stems, leaves, flowers, and fruit, with a particularly high expression in white fruit at the onset of coloration. Down-regulation of FaRIPK1 expression in strawberry fruit, using Tobacco rattle virus-induced gene silencing, inhibited ripening, as evidenced by suppression of ripening-related physiological changes and reduced expression of several genes involved in softening, sugar content, pigmentation, and ABA biosynthesis and signaling. The yeast-expressed LRR and STK (serine/threonine protein kinase) domains of FaRIPK1 bound ABA and showed kinase activity, respectively. A fruit disc-incubation test revealed that FaRIPK1 expression was induced by ABA and ethylene. The synergistic action of FaRIPK1 with FaABAR in regulation of strawberry fruit ripening is discussed.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Abscisic Acid / metabolism*
  • Cell Membrane / metabolism
  • Cell Nucleus / metabolism
  • Fragaria / genetics*
  • Fragaria / growth & development
  • Fruit / genetics
  • Fruit / growth & development*
  • Plant Proteins / genetics*
  • Plant Proteins / metabolism
  • Protein Kinases / genetics*
  • Protein Kinases / metabolism

Substances

  • Plant Proteins
  • Abscisic Acid
  • Protein Kinases