Cotylenins and Fusicoccins Stimulate Seed Germination of Striga hermonthica (Del.) Benth and Orobanche minor Smith

Abstract

Several fungal metabolites were examined for their effects on germination of the root parasitic weeds witchweed, Striga hermonthica (Del.) Benth, and clover broomrape, Orobanche minor Smith. Among these metabolites cotylenins (CNs) and fusicoccins (FCs) at concentrations as low as 10-5 M induced high seed germination (>50%) of both parasites. Inhibitors of ethylene biosynthesis [2-(2-aminoethoxyvinyl)glycine (AVG)] and action [silver thiosulfate (STS)] reduced CN- and FC-induced Striga germination but not that of Orobanche. This suggests that induction of Striga germination by CNs and FCs, as is the case with the true natural stimulant “strigol”, requires both ethylene biosynthesis and action, while that of Orobanche does not. Keywords: Cotylenin; fusicoccin; Orobanche minor; seed germination; Striga hermonthica

Effects of Fluridone and Norflurazon on Conditioning and Germination of Striga asiatica Seeds

“…Strigolactones, such as strigol (Cook et al 1966), sorgolactone , alectrol ) and orobanchol (Yokota et al 1998) are known as major seed germination stimulants exuded from host and non-host plant roots. In addition, dihydrosorgoleone, which was isolated from the hydrophobic exudates of sorghum roots (Chang et al 1986), jasmonic acid (Yoneyama et al 1998a), cotylenin and fusicoccin (Yoneyama et al 1998b) have been demonstrated to induce seed germination. The germination stimulants elicit ethylene biosynthesis in Striga seeds, which is essential to initiate seed germination (Logan and Stewart 1991;Yoneyama et al 1998b;Sugimoto et al 2003).…”

“…In addition, dihydrosorgoleone, which was isolated from the hydrophobic exudates of sorghum roots (Chang et al 1986), jasmonic acid (Yoneyama et al 1998a), cotylenin and fusicoccin (Yoneyama et al 1998b) have been demonstrated to induce seed germination. The germination stimulants elicit ethylene biosynthesis in Striga seeds, which is essential to initiate seed germination (Logan and Stewart 1991;Yoneyama et al 1998b;Sugimoto et al 2003). Moreover, the conditioning with fluridone induced the formation of haustoriumlike structures in S. asiatica seedlings.…”

Integrated Pest Management in Chickpea

“…Recently, much attention has been focused on the isolation and identification of novel metabolites including those isolated from plant root exudates and fungal metabolite. The fungal metabolite cotylenins and fusicoccins have been reported to induce over 50% seed germination of O. minor even at very low concentrations (Yoneyama et al, 1998). Germination stimulants, both natural and synthetic, have good potential as effective tools of management of broomrape, but much remains to be learned about their structure, activity, and stability in the soil.…”

Requirement for particular seed‐borne fungi for seed germination and seedling growth of Xyris complanata, a pioneer monocot in topsoil‐lost tropical peatland in Central Kalimantan, Indonesia

“…As a matter of fact, an experiment designed to separate seeds and mycelia physically with a cellophane film demonstrated that certain diffusible chemical(s) serve as signals for the promotion of seed germination (Bruns and Read 2000). As with these ericaceous, myco-heterotrophic plants, dormant seeds of remarkably small size often receive chemical stimulants from specific hosts or other biotic and/or abiotic chemical sources (Hauck et al 1992;Yoneyama et al 1998;Flematti et al 2004), while some plants awaiting dormancy breakage for seed germination in seed banks in the soil often require biological and/or physical decomposition of the seed coat (Warrag and Eltigani 2005;Baskin and Baskin 2004).…”