MmZFP1 Response to Abiotic Stress in the Invasive Plant Mikania micrantha

Mikania micrantha is one of the most problematic invasive alien species in China, and has had a serious economic and environmental impact. In the majority of plant genera, Cys2/His2-type zincfinger proteins (C2H2-type ZFPs) are involved in abiotic stress responses. In the present study, MmZFP1, a two-fingered C2H2-type ZFP gene, was cloned and characterized from Mikania micrantha. MmZFP1 has two C2H2-type finger domains and other three conserved regions, including a B-box, an L-box and a DLN-box, which may be located in the nucleus. In our experiments MmZFP1 was strongly expressed in ischolar_mains, but weakly in stems and leaves. In Mikania micrantha the expression of MmZFP1 could be induced by ABA, by dehydration and by high salinity. Observations of the phenotypes indicated that constitutive expression of MmZFP1 in transgenic lines resulted in growth retardation and this could be correlated with the expression level of MmZFP1. Over-expression of MmZFP1 in Arabidopsis thaliana can up-regulate the expression levels of the drought stress tolerance genes including ABF3 and ABF4 under normal growing conditions, which results in improved tolerance to drought. Both of the stress tolerance genes are involved in ABA-dependent pathways. Thus, our results suggest that MmZFP1 plays a key role in drought stress resistance, and this information is helpful in providing further understanding the molecular mechanism of the high degree of environmental adaptability of Mikania micrantha.