Analysis of the Function of the Anoectochilus Roxburghii Hd-Zip19 in Flower Development and Drought Responses

Abstract

Homeodomain‐leucine zipper (HD-ZIP) is an important transcription factor family, which not only affects the growth and development of plants, but also plays an important role in response to drought stress. ArHDZ19, a HD-ZIPⅢ family gene, is strongly induced by drought stress in Anoectochilus roxburghii. However, the function of ArHDZ19 in A. roxburghii growth regulation and drought response remained unclear. In this study, ArHDZ19 was located in the nucleus and had the highest expression in roots of A. roxburghii at flowering stage. Under normal condition, overexpression of ArHDZ19 increased the length of stamens and pistils in Arabidopsis. The phenotype of early flowering, as well as higher plant height were observed in overexpression ArHDZ19 (OE-ArHDZ19) lines. Furthermore, the expression of flowering-related genes SUPPRESSOR OF CONSTANS OVEREXPRES-SION 1 (SOC1) or CONSTANS (CO) was up-regulated in the transgenic lines, whereas the expression of FLOWERING LOCUS T (FT), FLOWERING LOCUS C (FLC) and GIGANTEA (GI) were down-regulated. Overexpression of ArHDZ19 increased the tolerance of transgenic Arabidopsis under drought stress, which have higher plant height than WT. And the expression of COLD-REGULATED 47 (COR47), KINESIN 1 (KIN1), RESPONSIVE TO DEHYDRATION 22 (RD22), and RESPONSE TO DESICCATION (RD29A) were up-regulated in OE-ArHDZ19 lines under drought treatment. The results indicated that ArHDZ19 can improve drought stress response in plants by influencing flowering time, which might be drought avoidance.

Keywords: Anoectochilus roxburghii, HD-ZIP transcription factor, Early flowering, Drought stress