Special issue in honour of Prof. Reto J. Strasser - Influence of Cuscuta campestris Yunck. on the photosynthetic activity of Ipomoea tricolor Cav. - in vivo chlorophyll a fluorescence assessment

Abstract

Cuscuta campestris Yunck. is a parasitic plant, acquiring nutrients from the hosts. Although a generalist, its hosts differ in their susceptibility. Ipomoea tricolor Cav. is a semi-compatible host - C. campestris growth is restricted in infected plants. We aimed to assess the effect of the parasite on this semi-compatible host by using the sensitive JIP-test to follow physiological changes in leaves at different vegetative stages - aged, mature, and newly emerging. The characteristics of the photosynthetic machinery were estimated by 17 parameters, calculated from the prompt chlorophyll a fluorescence. The most sensitive were performance index of photosystem II, performance index of photosystems I + II, and number of QA redox turnovers until maximal fluorescence is reached. The infected I. tricolor plants responded to the parasite by activating the electron transport in PSII in later periods. The oldest leaves and the youngest leaves developed certain adaptation to the parasite but the younger did not. The effect of the parasite on the photosynthetic apparatus depended on the physiological age of the host plant leaves.

Keywords

• haustoria
• holoparasitic plant
• photosystem i
• photosystem ii
• stem parasite