Transcriptional responses of Rosa rugosa to salt stress and salt shock

Abstract

Rugosa rugosa has high tolerance to various stresses; however, the molecular mechanisms of this behavior under adverse conditions are unclear. The objective of this study is to investigate expression patterns of stress-related genes in response to salinity stress. Changes in transcript levels of R. rugose, grown under different salt stress conditions (0, 25, 50, and 100 mM NaCl) over a long exposure period (30 days), have been investigated. In addition, the effects of salt shock stress on seedlings exposed to a high level (200 mM) of NaCl for a relatively short duration (3 h) have also been investigated. Expression levels of selected differentially expressed genes have been determined using relative reverse transcription polymerase chain reaction (RT-PCR). It has been observed that seedlings exposed to salt stress for a long duration exhibited no signs of stress in both leaves and roots. In addition, expression of NHX1 in R. rugosa increased in the presence of NaCl. Furthermore, transcripts of EXP4, GPP, NHX1, NAC, and DREB genes also increased under high levels of NaCl. In contrast, expression levels of MYB and TIR decreased during this salt shock treatment. Of particular interest is the increase in levels of transcripts of NHX1 in leaves of seedlings grown under both salt stress and salt shock conditions, thus suggesting that this gene plays an important role in salt stress tolerance in R. rugosa. These findings will support efforts in enhancing salt tolerance in roses, and perhaps in other members of the Rosaceae family.