First Report of Orobanche laxissima Parasitizing Pallis’ Ash (Fraxinus pallisiae) in Georgia

Abstract

HomePlant DiseaseVol. 104, No. 6First Report of Orobanche laxissima Parasitizing Pallis’ Ash (Fraxinus pallisiae) in Georgia PreviousNext DISEASE NOTES OPENOpen Access licenseFirst Report of Orobanche laxissima Parasitizing Pallis’ Ash (Fraxinus pallisiae) in GeorgiaR. Piwowarczyk, D. Gmiter, K. Durlik, K. Ruraż, and W. KacaR. Piwowarczyk†Corresponding author: R. Piwowarczyk; E-mail Address: [email protected]http://orcid.org/0000-0003-0507-7835Department of Microbiology and Parasitology, Institute of Biology, Jan Kochanowski University in Kielce, 25-406 Kielce, PolandSearch for more papers by this author, D. GmiterDepartment of Microbiology and Parasitology, Institute of Biology, Jan Kochanowski University in Kielce, 25-406 Kielce, PolandSearch for more papers by this author, K. DurlikDepartment of Microbiology and Parasitology, Institute of Biology, Jan Kochanowski University in Kielce, 25-406 Kielce, PolandSearch for more papers by this author, K. RurażDepartment of Microbiology and Parasitology, Institute of Biology, Jan Kochanowski University in Kielce, 25-406 Kielce, PolandSearch for more papers by this author, and W. KacaDepartment of Microbiology and Parasitology, Institute of Biology, Jan Kochanowski University in Kielce, 25-406 Kielce, PolandSearch for more papers by this authorAffiliationsAuthors and Affiliations R. Piwowarczyk † D. Gmiter K. Durlik K. Ruraż W. Kaca Department of Microbiology and Parasitology, Institute of Biology, Jan Kochanowski University in Kielce, 25-406 Kielce, Poland Published Online:25 Mar 2020https://doi.org/10.1094/PDIS-10-19-2113-PDNAboutSectionsSupplemental ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmailWechat Orobanche laxissima Uhlich & Rätzel (Orobanchaceae) occurs in the Caucasus Mountains and Transcaucasia. It is an expansive polyphagous root holoparasitic weed that infects many wild and sometimes cultivated trees and shrubs, from such families as Betulaceae, Oleaceae, Fagaceae, Aceraceae, and Cornaceae (Piwowarczyk et al. 2019). The native range of Fraxinus pallisiae Wilmott (Oleaceae) is southeast Europe to Moldova, Anatolia in Turkey, and the Russian part of the Caucasus (Harvey-Brown and Rivers 2018). F. pallisiae in the Georgian Caucasus has not previously been recorded (specimens were identified by Prof. Jerzy Zieliński from Institute of Dendrology of the Polish Academy of Sciences). Field surveys conducted in south eastern Georgia in May 2014 and 2019 revealed extensive infestations of O. laxissima on the roots of F. pallisiae in one locality in Kakheti province, at the foot of the Greater Caucasus range, near Giorgitsminda, in an ash cultivation (41°43′15″N, 45°22′19″E, 755 m elevation). The infection was confirmed by verifying the attachment of the Orobanche to the Fraxinus root. Specimens of parasite and host are deposited in the KTC herbarium of the Jan Kochanowski University in Kielce. The population of the parasite consisted of at least 2,000 shoots. A single plant of ash was parasitized by several to 100 broomrape plants, and 30 to 40% of the approximately 1-ha location was infested. The main botanical features of the O. laxissima are (i) stem simple, (10 to) 25 to 40 (to 100) cm high, purple, violet, reddish, pink, or yellow, with haustoria; (ii) inflorescence usually long to short cylindrical, rather lax, usually many-flowered; (iii) calyx segments entire or bidentate; (iv) corolla (16 to) 22 to 24 (to 31) mm long, tubular bell shaped; purple, dark or light pink, rarely dirty yellow, light brown; (v) stigma dark pink, purple, violet, orange, or yellow; and (vi) parasitic on the roots of trees and shrubs (Piwowarczyk et al. 2019). For sequence comparison, the total genomic DNA was extracted and the internal transcribed spacer (ITS) region was amplified following the protocols of Piwowarczyk et al. (2018) with primers ITS7A and ITS4. The PCR product was sequenced on both strands at Genomed S.A. Raw reads were aligned using MUSCLE software (Edgar 2004) and then manually corrected and trimmed. The sequence (637 bp) was deposited in GenBank (accession no. MN524166). A phylogenetic tree was generated in SeaView version 4 (Gouy et al. 2010). A BLAST search of the sequence against the GenBank database showed the highest similarity (up to 99%) to sequences of O. laxissima (the first three ITS sequences aligned: KR260927, KR260917, and KR260916), which strongly supports expectations that the sample belonged to the O. laxissima species. So far, two species in the genus Fraxinus, F. angustifolia Vahl and F. excelsior L., are known hosts for O. laxissima. To the best of our knowledge, this is the first report of O. laxissima parasitizing F. pallisiae. The parasite appeared here in large numbers, and infected trees, especially young ones, were weak with sparse foliage. O. laxissima seems to be the most expansive species in the Caucasus currently, listed previously from natural habitats. However, our recent observations on tree plantations suggest the economic importance of the species in the future, because it may spread to adjacent cultivated areas. Because this species is capable of attacking multiple tree species in several different plant families, it has the potential to attack fruit trees and shrubs.The author(s) declare no conflict of interest.