AtLRRop2, an leucine-rich repeat-only protein, mediates cold stress response in <i>Arabidopsis thaliana</i>

Abstract

Cold stress is one of the main abiotic stresses that cause major damage to plant growth and development. Plants activate a number of response mechanisms to increase tolerance to environmental stresses. To investigate the important components of cold stress signaling in plants, we identified a novel Arabidopsis thaliana gene, which encodes an leucine-rich repeat-only protein, AtLRRop2 (At2g20210), and demonstrated its role in the cold stress response. Amino acid sequence analysis of AtLRRop2 revealed the presence of four leucine-rich repeat (LRR) motifs that mediate protein-protein interactions. To determine the function of AtLRRop2 in cold stress response, we identified three independent T-DNA insertion mutants, atlrrop2-1, atlrrop2-2, and atlrrop2-3, and examined the transcript levels by reverse transcription PCR (RT-PCR). The results revealed that atlrrop2-1 and atlrrop2-2 are knockout mutants, while atlrrop2-3 is a knockdown mutant. All three mutants were more sensitive to cold stress than the wild type (Col-0), although atlrrop2-3 mutant plants were less sensitive to chilling and freezing temperatures than atlrrop2-1 and atlrrop2-2 plants. Taken together, these results suggest that AtLRRop2 plays an important role in cold stress signaling in Arabidopsis.