MdDREB2A in apple is involved in the regulation of multiple abiotic stress responses

Abiotic stress has a serious effect on plant growth.The transcription factor DREB2A is a member of the AP2/ERF family,which is widely involved in abiotic stress response.However,the function of apple MdDREB2A has not been systematically investigated.In this study,MdDREB2A was isolated from the cultivar‘Royal Gala’.The open reading frame of MdDREB2A was 1197 bp in length and it encoded a protein of 398 amino acidswithmolecularweight of 43.8 kD.As a transcription factor,MdDREB2Awas located in the nucleus.qRT-PCR analysis showed that MdDREB2A was involved in responses to drought,salt,and ABA stresses.Under these stress treatments,the relative electrical conductivity,superoxide anion and malondialdehyde(MDA)in transgenic materials significantly decreased,and the content of proline increased in MdDREB2A transgenic plants,compared to the controls,indicating that MdDREB2A transgenic apple calli and transgenic Arabidopsis exhibited improved resistance to abiotic stress.This study introduces a candidate gene for the genetic improvement of crop resistance and reveals important function of MdDREB2A in the regulation of abiotic stress response.

Interfering small ubiquitin modifiers(SUMO)improves the thermotolerance of apple by facilitating the activity of MdDREB2A

Heat stress,which is caused by global warming,threatens crops yield and quality across the world.As a kind of post-translation modification,SUMOylation involves in plants heat stress response with a rapid and wide pattern.Here,we identified small ubiquitin modifiers(SUMO),which affect drought tolerance in apple,also participated in thermotolerance.Six isoforms of SUMOs located on six chromosomes in apple genome,and all the SUMOs were up-regulated in response to heat stress condition.The MdSUMO2 RNAi transgenic apple plants exhibited higher survival rate,lower ion leakage,higher catalase(CAT)activity,and Malondialdehyde(MDA)content under heat stress.MdDREB2A,the substrate of MdSUMO2 in apple,was accumulated in MdSUMO2 RNAi transgenic plants than the wild type GL-3 at the protein level in response to heat stress treatment.Further,the inhibited SUMOylation level of MdDREB2A in MdSUMO2 RNAi plants might repress its ubiquitination,too.The accumulated MdDREB2A in MdSUMO2 RNAi plants further induced heat-responsive genes expression to strengthen plants thermotolerance,including MdHSFA3,MdHSP26.5,MdHSP18.2,MdHSP70,MdCYP18-1 and MdTLP1.In summary,these findings illustrate that interfering small ubiquitin modifiers(SUMO)in apple improves plants thermotolerance,partly by facilitating the stability and activity of MdDREB2A.