The response of dodder {Cuscuta spp.) seedlings to phytohormones under various light regimes

Abstract

Phytohormones were screened for their effects on induction of coiling and prehaustoria in de-etiolated excised dodder seedlings under different light treatments. Zeatin stimulated coiling and the formation of prehaustoria under all light tested, even in darkness. A synergistic effect was observed with zeatin and far-red light (700-800 nm) but not with red light (600-700 nm) on the formation of prehaustoria. Application of indole-3acetic acid inhibited zeatin-induced coiling and prehaustoria development under blue (400-SO0 nm) and a mixture of red plus far-red light. but not in blue plus far-red light. Ethylene had no effect on coiling and prehaustoria development. Observations suggest that zeatin-induced coiling and prehaustoria development may be mediated by phytochrome.

Glucosinolates from Host Plants Influence Growth of the Parasitic Plant Cuscuta gronovii and Its Susceptibility to Aphid Feeding

“…As in autotrophic plants, auxin mediates developmental processes in dodder such as apical tip dominance (Maheshwari and Sreekrishna, 1982). It also plays a role in regulating the development of dodder's feeding organs (haustoria): when applied exogenously to dodder seedlings in vitro, auxin inhibits the induction of prehaustorial outgrowths caused by exogenous zeatin or far-red light (Haidar et al, 1998). In contrast, plants in our study successfully formed these outgrowths and attached to all host types irrespective of host auxin content.…”

Interspecific RNA Interference of SHOOT MERISTEMLESS-Like Disrupts Cuscuta pentagona Plant Parasitism

“…The haustorium initial originates from dedifferentiation of cortical parenchyma between the vascular stele and the epidermis (Lee, 2007), on the side of the dodder strand in contact with the host, in response to mechanical, light, and hormonal cues (Haidar et al, 1998;Furuhashi et al, 2011). The cells of the epidermis in contact with the host become elongated and branched (Lee, 2007), forming an adhesive junction above a region of meristematic cells (Lee, 2007).…”

“…An increase in cytokinin precedes induction of haustoria, and cytokinin is required for their development (Haidar et al, 1998;Furuhashi et al, 2011). Members of the KNOTTED1-like HO-MEOBOX1 (KNOX1) gene family are known to promote cytokinin biosynthesis in the shoot apical meristem (SAM) (Jasinski et al, 2005), and KNOX1 genes are well established as regulators of indeterminate identity in the SAM throughout angiosperms (Chuck et al, 1996(Chuck et al, , 1998Long et al, 1996;Kerstetter et al, 1997;Hake et al, 2004).…”

The biology of Canadian weeds. 133. Cuscuta campestris Yuncker, C. gronovii Willd. ex Schult., C. umbrosa Beyr. ex Hook., C. epithymum (L.) L. and C. epilinum Weihe.

“…Chryptochromes interact synergistically with the Pr (red light absorbing) form of phytochrome, and antagonistically with Pfr form in mediating initiation and coiling of prehaustoria (Haidar 2003). Phytochrome B (Furuhashi et al 1997) or phytochrome A (Haidar et al 1998) may be involved. Tactile stimulation determined twining and prehaustoria initiation in blue and a mixture of blue/far-red light, but not in darkness or fluorescent white light (Tada et al 1996;Haidar et al 1997).…”

“…Tactile stimulation determined twining and prehaustoria initiation in blue and a mixture of blue/far-red light, but not in darkness or fluorescent white light (Tada et al 1996;Haidar et al 1997). Coiling and development of prehaustoria occurred in the presence of cytokinins or zeatin, whereas indole-3-acetic acid (IAA) and abscisic acid (ABA), or their combination, had an opposite effect (Tsivion 1978;Rajagopal et al 1988;Haidar et al 1998;Ramasubramanian et al 1988). Zeatin had a synergistic effect with far-red light but not with red light (Haidar et al 1998).…”