Carbohydrate regulation of attachment, encystment, and appressorium formation by Pythium porphyrae (Oomycota) zoospores on Porphyra yezoensis (Rhodophyta)

Abstract

Pythium porphyrae Takahashi et Sasaki, a facultative parasite of Porphyra spp., is the common microbial agent responsible for red rot disease of this red alga in Japan. Host infection by this species and other plant parasitic members of the Pythiaceae is initiated by motile biflagellate zoospores. Factors regulating host specificity and the initial steps involved in the infection process, consisting of attachment, encystment and appressorium formation, are not known. Zoospore encystment and appressorium formation of P. porphyrae were monitored by staining of the fungal cell walls using calcofluor. The zoospores infected only Porphyra spp. and Bangia atropurpurea (Roth) C. Agardh thalli, although they attached to, and encysted on, many other members of the Rhodophyceae ( Stylonema alsidii [Zanardini] Drew, Gelidium elegans Kützing, Pterocladiella capillacea [Gmelin] Santelices et Hommersand, Carpopeltis affinis [Harvey] Okamura, Gloiosiphonia capillaris [Hudson] Carmichael in Berkeley, Grateloupia turuturu Yamada, Callophyllis adhaerens Yamada, Gracilaria spp., Lomentaria hakodatensis Yendo, Rhodymenia intricata [Okamura] Okamura, Griffithsia subcylindrica Okamura, Wrangelia tanegana Harvey, and Polysiphonia morrowii Harvey). No attachment or encystment was observed on the red alga Kappaphycus striatum (Schmitz) Doty ex Silva in Silva et al., the brown algae Undaria pinnatifida (Harvey) Suringar, Scytosiphon sp., and Sargassum thunbergii (Mertens ex Roth) Kuntze as well as members of the Ulvaceae (green algae). Sequential extraction of carbohydrates from Porphyra yezoensis Ueda thalli and the addition of diverse monosaccharides, polysaccharides, and amino acids to zoospore suspensions indicated that encystment and appressorium formation were induced only by sulfated galactans (porphyran, commercial agar, agarose, and carrageenans). Zoospore attachment and encystment on thalli of P. yezoensis was abolished by periodate oxidation of the thallus surface and was reduced by 80-90% after enzymatic removal of sulfated galactan (porphyran). It appears that the interaction of zoospore surface receptors with sulfated ga-lactan (porphyran) determinants on the thallus surface induced specific attachment and encystment on Porphyra spp. thalli. Zoospores encysted, germinated, and formed appressoria on sulfated galactan films and in suspensions of this carbohydrate. Attachment and encystment were induced on commercial agar and agarose films, but appressoria were not induced on agarose films. Supplementation of agarose media with both cold and hot water fractions and with porphyran from P. yezoensis -induced appressoria implicated sulfated galactans (porphyran) in appressorium formation.

Infection and cox2 sequence of Pythium chondricola (Oomycetes) causing red rot disease in Pyropia yezoensis (Rhodophyta) in Korea

“…Our isolate also did not infect filamentous gametophytic Bangiales ("Bangia") nor any filamentous sporophytic phases ('conchocelis') which has been suggested before based on infection of Pythium marinum Sparrow (Kerwin et al 1992), a species in clade B of Pythium (Lévesque and De Cock 2004). The cell wall composition of conchocelis phases is known to differ from the gametophytes (Mukai et al 1981, Vreeland andKloareg 2000), and carbohydrates are known to be important in spore attachment and penetration in P. porphyrae (Uppalapati and Fujita 2000). In our experiments, P. porphyrae was not able to infect members of the Florideophyceae, while the original collection of P. chondricola was from decaying red algae (e.g., Chrondrus crispus) but it is unclear if Pythium was a necrotroph or a saprotroph from the original descriptions (De Cock 1986).…”

A revaluation of algal diseases in Korean Pyropia (Porphyra) sea farms and their economic impact

“…Red-rot disease was first reported by Arasaki (1947) and best studied, yet it took three decades to isolate and name its causative agent, the oomycete Pythium porphyrae Takahashi et Sasaki (Takahashi et al 1977). Although the ecological nature of epidemics and the physiological characteristics of this pathogen have been investigated intensively, there are very few cellular and molecular studies on the mechanisms of infection (Uppalapati and Fujita 2000a, 2000b, Park et al 2001a, 2001b, Uppalapati et al 2001, Addepalli et al 2002, Hwang et al 2009). Other pathogens are more poorly known; the pathogen causing "chytrid blight" of Pyropia in Japan was recently isolated and named Olpidiopsis porphyrae Sekimoto, Yokoo, Kawamura et Honda (Sekimoto et al 2008).…”

Loss of Abaxial Leaf Epicuticular Wax inMedicago truncatula irg1/palm1Mutants Results in Reduced Spore Differentiation of Anthracnose and Nonhost Rust Pathogens

“…Surface chemical and physical signals are known to affect adhesion, germination, and differentiation of preinfection structures in pathogenic fungi (Podila et al, 1993;Kolattukudy et al, 1995;Uppalapati and Fujita, 2000). Therefore, based on our pathogen assays and our observation that the abaxial leaf (A) Complementation of rust preinfection structure formation of P. pachyrhizi by expression of PALM1 in the irg1-1/palm1-5 mutant (R108 ecotype background).…”