Occurrence and genetic similarity of Diplodia pinea on shoots and cones in seed orchards of Pinus spp. in north-western Turkey

Abstract

Doğmuş-Lehtijärvi H.T., Kaya A.G.A., Lehtijärvi A., Oskay F., Kaya Ö.D. (2014): Occurrence and genetic similarity of Diplodia pinea on shoots and cones in seed orchards of Pinus spp. in north-western Turkey. Plant Protec Sci., 50: 217-220.Diplodia shoot blight disease can cause significant damage on coniferous trees and be particularly injurious to cones, which reduces the amount of seed production and germination. We investigated the disease severity and genetic variation of Diplodia pinea in one Pinus nigra and two P. sylvestris seed orchards. Disease surveys were carried out in İzmit (Marmara region, Turkey) in May 2012. Symptomatic shoots and cones were examined for the presence of pycnidia. Cultural and morphological characteristics of the isolates were studied using cultures grown on potato dextrose agar (PDA). Based on morphological characteristics and results using species specific primers, the pycnidia on shoots and cones were identified as D. pinea. In addition, Random Amplified Microsatellite Sequence (RAMS) analyses indicated that there was a single genet of D. pinea which caused the disease in the seed orchards. All of the 60 sampled trees were found to be infected by the fungus. There were differences in disease severity among the stands.Keywords: diplodia shoot blight; pine; RAMS; disease severity Diplodia pinea (Desm.) Kickx is a latent, opportunistic conifer pathogen which causes the disease commonly known as Diplodia shoot blight (Eldridge 1961;Swart & Wingfield 1991;Stanosz et al. 1997). The fungus affects both young and old trees causing shoot blight, dead top, sap stain, root disease, and cankers on stems and branches (Brookhouser & Peterson 1971;Peterson 1977).It mostly attacks Pinus species but also Abies Mill., Chamaecyparis Spach., Cupressus L., Larix Mill., Picea A. Dietr., Pseudotsuga Carriere and Thuja L. (Sinclair & Lyon 1987;Swart et al. 1987;Chou & MacKenzie 1988;Nicholls & Ostry 1990;Stanosz et al. 2001; Wingfield & Knox-Davies 1980;Palmer & Nicholls 1985;Rees & Webber 1988;Stanosz & Cummings-Carlson 1996). Although D. pinea has been already reported in Turkey (Günay 2001), little is known about the development of the disease in Turkish forests. Some of the most severe damages have occurred in southern Turkey. The pathogen was noted on dead twigs and canker samples of P. elderica and P. brutia in Kahramanmaraş in 2005. Several years later it was found on Pseudotsuga menziesii in İzmit province (Kaya et al. 2014). Studies carried out in the western part of the Taurus Mts. in Isparta province, located in the Mediterranean part of Turkey, showed that D. pinea was the most common cause of the shoot blight of P. brutia Ten. (Doğmuş-Lehtijärvi et al. 2007).In 2013, we investigated one P. nigra and two P. sylvestris seed orchards infested by D. pinea in Presented at the IUFRO Meeting "Biosecurity in Naturals Forests, Stands and Plantations, Genomics and Biotechnology for Biosecurity in Forestry", Brno and Cerna Hora, Czech Republic, May 20-25, 2013. 218 Vol. 50, 2014, No. 4: ...

Comparison of Diplodia Tip Blight Pathogens in Spanish and North American Pine Ecosystems

“…An important difference between the previous and the present study is the sampling that was intensively performed within Basque Country plantations. Nevertheless, this result contrasts with other studies of the fungus showing that genetic diversity among D. sapinea populations is low at the global scale [27,83,84]. This contradiction may be due to methodological differences.…”

“…The low genetic diversity has been explained based on the success of some genotypes as endophytes. The close association of D. pinea as an endophyte with pines suggests the ability to overcome pressure regardless of the external environmental conditions [84]. This fact coupled with no evidence of sexual reproduction would explain the clonality found within global populations of D. pinea, although recent studies showed a cryptic sexual stage in this species [82].…”