Gerbera POE1 (GhPOE1) is involved in leaf senescence in Arabidopsis

Abstract

Senescence, the final stage of plant development, is a complex and highly controlled physiological process. Senescence occurs in various tissues and organs, and is especially apparent in leaves. Pollen Ole e 1 (POE1) proteins are known to initiate pollen germination, participate in the response to various stresses, and be involved in root development and seed germination. However, their role in plant senescence is not well defined. Using transcriptome data, we isolated a novel protein from Gerbera hybrida (gerbera) which is an ortholog of AT2G34700 (which encodes a Pollen Ole e 1 domain protein in Arabidopsis thaliana) and named GhPOE1. This protein is localized in the cytoplasm and expresses mainly in disk florets, old leaves, and old roots. We transformed GhPOE1 into wild-type Arabidopsis (Col-0) and obtained homozygous transgenic lines OE2, OE3 and OE5. Overexpression of GhPOE1 in these lines led to yellowing rosette leaves with decreased chlorophyll content and photochemical efficiency. Moreover, senescence-associated genes such as SAG12, SAG13, WRKY53, and SIRK (senescence-induced receptor-like kinase) were significantly up-regulated, and the photosynthesis-associated genes CAB2 (chlorophyll a/b-binding 2) and RBCS (ribulose bisphosphate carboxylase small chain) were down-regulated in the transgenic plants. Our results showed that GhPOE1 is a positive regulator of senescence that can promote leaf senescence in Arabidopsis. GhPOE1 is a new candidate gene for genetic engineering to prolong the vase life of cut gerbera flowers.