F-Box Family Genes, LTSF1 and LTSF2, Regulate Low-Temperature Stress Tolerance in Pepper (Capsicum chinense).

Jelli Venkatesh,Byoung-Cheorl Kang,Jin-Kyung Kwon,Min-Young Kang,Li Liu

doi:10.3390/plants9091186

Abstract

The F-box proteins belong to a family of regulatory proteins that play key roles in the proteasomal degradation of other proteins. Plant F-box proteins are functionally diverse, and the precise roles of many such proteins in growth and development are not known. Previously, two low-temperature-sensitive F-box protein family genes (LTSF1 and LTSF2) were identified as candidates responsible for the sensitivity to low temperatures in the pepper (Capsicum chinense) cultivar ‘sy-2’. In the present study, we showed that the virus-induced gene silencing of these genes stunted plant growth and caused abnormal leaf development under low-temperature conditions, similar to what was observed in the low-temperature-sensitive ‘sy-2’ line. Protein–protein interaction analyses revealed that the LTSF1 and LTSF2 proteins interacted with S-phase kinase-associated protein 1 (SKP1), part of the Skp, Cullin, F-box-containing (SCF) complex that catalyzes the ubiquitination of proteins for degradation, suggesting a role for LTSF1 and LTSF2 in protein degradation. Furthermore, transgenic Nicotiana benthamiana plants overexpressing the pepper LTSF1 gene showed an increased tolerance to low-temperature stress and a higher expression of the genes encoding antioxidant enzymes. Taken together, these results suggest that the LTSF1 and LTSF2 F-box proteins are a functional component of the SCF complex and may positively regulate low-temperature stress tolerance by activating antioxidant-enzyme activities.

Highlights

In plants, low temperatures affect many physiological processes, including water and nutrient uptake, photosynthesis, immune responses, growth, and development, as well as the geographical distribution of plants [1,2]
We characterized the LTSF1 and LTSF2 genes and proteins believed to be affected in the ‘sy-2’
The low-temperature stress-responsive LTSF1 and LTSF2 genes were predicted to encode F-box proteins containing a C-terminal FBA domain, which participates in protein–protein interactions associated with a wide range of plant physiological processes [31,32,33,34]

Summary

Introduction

Low temperatures affect many physiological processes, including water and nutrient uptake, photosynthesis, immune responses, growth, and development, as well as the geographical distribution of plants [1,2]. An important fruit crop grown worldwide, is temperature-sensitive, with an optimum temperature of 25–30 ◦ C [6,7]. Deviations from these temperatures can adversely affect growth and development, resulting in a variety of developmental and physiological disorders [6,7,8]. To elucidate the molecular basis of low-temperature sensitivity in plants, extensive studies have been performed using low-temperature-sensitive mutants

Methods

Results

Discussion

Conclusion