Y2SK2 and SK3 type dehydrins from Agapanthus praecox can improve plant stress tolerance and act as multifunctional protectants

摘要

Two dehydrins from Agapanthus praecox (ApY(2)SK(2) and ApSK(3)) show important protective effects under complex stresses. Both ApY(2)SK(2) and ApSK(3) contain one intron and consist of a full-length cDNA of 981 bp and 1057 bp encoding 186 and 215 amino acids, respectively. ApY(2)SK(2) and ApSK(3) transgenic Arabidopsis thaliana show reduced plasma membrane damage and ROS levels and higher antioxidant activity and photosynthesis capability under salt, osmotic, cold and drought stresses compared with the wild-type. ApY(2)SK(2) and ApSK(3) are mainly located in the cytoplasm and cell membrane, and ApY(2)SK(2) can even localize in the nucleus. In vitro tests indicate that ApY(2)SK(2) and ApSK(3) can effectively protect enzyme activity during the freeze-thaw process, and ApY(2)SK(2) also exhibits this function during desiccation treatment. Furthermore, ApY(2)SK(2) and ApSK(3) can significantly inhibit hydroxyl radical generation. These two dehydrins can bind metal ions with a binding affinity of Co2+>Ni2+>Cu2+>Fe3+; the binding affinity of ApSK(3) is higher than that of ApY(2)SK(2). Thus, ApY(2)SK(2) has a better protective effect on enzyme activity, and ApSK(3) has stronger metal ion binding function and effect on ROS metabolism. Moreover, plant cryopreservation evaluation tests indicate that ApY(2)SK(2) and ApSK(3) transformation can enhance the seedling survival ratio from 23% to 47% and 55%, respectively; the addition of recombinant ApY(2)SK(2) and ApSK(3) to plant vitrification solution may increase the survival ratio of wild-type A. thaliana seedlings from 24% to 50% and 46%, respectively. These findings suggest that ApY(2)SK(2) and ApSK(3) can effectively improve cell stress tolerance and have great potential for in vivo or in vitro applications.