Journal Article

Cuscuta australis (dodder) parasite eavesdrops on the host plants’ FT signals to flower

Shen, Guojing, Liu, Nian, Zhang, Jingxiong, Wu, Jianqiang, Xu, Yuxing, Baldwin, Ian T.

2020

Overview

Many plants use environmental cues, including seasonal changes of day length (photoperiod), to control their flowering time. Under inductive conditions, FLOWERING LOCUS T (FT) protein is synthesized in leaves, and FT protein is a mobile signal, which is able to travel to the shoot apex to induce flowering. Dodders (Cuscuta, Convolvulaceae) are root- and leafless plants that parasitize a large number of autotrophic plant species with varying flowering time. Remarkably, some dodder species, e.g., Cuscuta australis, are able to synchronize their flowering with the flowering of their hosts. Detailed sequence inspection and expression analysis indicated that the FT gene in dodder C. australis very likely does not function in activating flowering. Using soybean host plants cultivated under inductive and noninductive photoperiod conditions and soybean and tobacco host plants, in which FT was overexpressed and knocked out, respectively, we show that FT-induced flowering of the host is likely required for both host and parasite flowering. Biochemical analysis revealed that host-synthesized FT signals are able to move into dodder stems, where they physically interact with a dodder FD transcription factor to activate dodder flowering. This study demonstrates that FTs can function as an important interplant flowering signal in host–dodder interactions. The unique means of flowering regulation of dodder illustrates how regressive evolution, commonly found in parasites, may facilitate the physiological synchronization of parasite and host, here allowing the C. australis parasite to time reproduction exactly with that of their hosts, likely optimizing parasite fitness.

• Publisher: National Academy of Sciences
• Subject: Animals / Biochemical analysis / Biological Sciences / Cuscuta - parasitology / Cuscuta - physiology / Cuscuta australis / Flowering / FLOWERING LOCUS T gene / Flowers & plants / Flowers - parasitology / Flowers - physiology / Gene Expression Regulation, Plant - physiology / Glycine max - parasitology / Glycine max - physiology / Host plants / Host-Parasite Interactions - physiology / Inspection / Nicotiana - parasitology / Nicotiana - physiology / Parasites / Parasites - physiology / Parasitic plants / Plant Biology / Plant Leaves - parasitology / Plant Leaves - physiology / Plant species / Proteins / Regression analysis / Seasonal variations / Soybeans / Synchronism / Synchronization / Synthesis / Tobacco / Transcription Factors - metabolism