Ion flux kinetics in blue light‐grown field dodder (Cuscuta campestris) seedlings

Abstract

Previous studies have revealed that blue light stimulates coiling and prehaustoria development in young de-etiolated dodder seedlings prior to host attachment. In this study, the Ca 2+ and H + flux kinetics that are associated with blue light-mediated coiling and prehaustoria development in de-etiolated dodder seedlings were measured uninvasively using the ion-selective, vibrating microelectrode ion flux system. The findings showed that blue light induces rapid transient changes in the net Ca 2+ and H + fluxes. A clearly pronounced lag of about several minutes was observed between the blue light-induced changes in the Ca 2+ and H + fluxes, with H + being a leading ion. The addition of 1 mol L −1 vanadate, a known blocker of the plasma-membrane H + -ATPase, to the bathing solution completely prevented both the H + and the Ca 2+ flux responses and inhibited coiling and prehaustoria development, suggesting a causal relationship between the blue light-induced changes in the net Ca 2+ and H + fluxes and seedling movements. It is concluded that the plasma-membrane H + -ATPase plays a key role in a dodder's parasitic mode of growth and its adaptive response to the environment.

Variability in Early Seed Development of 26 Populations of Cuscuta campestris Yunck.: The Significance of Host, Seed Age, Morphological Trait, Light, Temperature, and Genetic Variance

“…Seed response to light is important for preventing germination in places and at times unfavorable for seedling establishment and survival, and de-etiolated dodder seedlings must especially detect and respond to light quality, intensity, and direction to survive. Light provides de-etiolated dodder seedlings with the necessary environmental information that initiates changes in their two modes of vital activity, i.e., from the higher plant mode of growth to the parasitic mode of growth [58][59][60]. In the field, Cuscuta seedlings may grow directly toward a light source and the green canopy of potential nearby hosts [58,59].…”