Review Article Open Access Jabnoun-Khiareddine et al., J Plant Pathol Microbiol 2018, 9:9 DOI: 10.4172/2157-7471.1000450 Journal of Plant Pathology & Microbiology J o u r n a l o f P l a n t P a t h ol o g y & M i c r o b i o l o g y ISSN: 2157-7471 Research Article Open Access Volume 9 • Issue 9 • 1000450 J Plant Pathol Microbiol, an open access journal ISSN: 2157-7471 Keywords: Characterization; Coniella granati; Dieback; Fruit rot; Pathogenicity; Punica granatum L.; Tunisia. Introduction Pomegranate (Punica granatum L.) is mostly cultivated in the Mediterranean Basin, Southern Asia and several countries in North and South America. It is a temperate climate species requiring high temperatures to mature properly [1]. Tunisia is one of the main regions for pomegranate cultivation and production [2,3] and is considered as a micro-gene center with more than 60 local ecotypes already collected [4]. Te main Tunisian producing regions are Gabes and Gafsa oases, Cap Bon, Bizerte and Sousse where pomegranate plays an important ecological and socio-economic role [4,5]. In Tunisia, as well as in many other countries [6], pomegranate has traditionally been considered a hardy tree, sufering from few diseases as compared to most fruit trees. Nevertheless, in the last decade, many fungal diseases were reported in many regions of the globe and were currently classifed as one of the most limiting factors for pomegranate cultivation. For instance, wilt due to Ceratocystis fmbriata [7], wood canker and branch dieback caused by Cytospora punicae [8], and root and crown rot incited by Phytophthora palmivora [9] were detected in many countries. Also, Lasiodiplodia gilanensis, associated to severe dieback of one to multiple branches in California [6], and Neofusicoccum parvum, involved in shoot blight and canker symptoms, are reported to occur on pomegranate trees in Greece [10]. Several fungi are also common pomegranate fruit rot pathogens such as Alternaria spp. [11], Penicillium spp. [12,13], Aspergillus spp. [14], Botrytis cinerea [15], Colletotrichum gloeosporioides, and Pestalotia brevista [16]. Tey are responsible for substantial losses occurring before and afer harvest and are threatening the pomegranate production. Despite this high number of fungi being identifed as pathogens causing pomegranate dieback and fruit rots, little information is available about fungal diseases afecting pomegranates in Tunisia. Cytospora punicae, involved in canker and severe branch dieback, was the only fungal species identifed in Gabes region on June 2014 on cv. Gabsi plants which was associated with a disease incidence of about 8% [17]. However, in a recent survey made in several orchards located in diferent regions of the governorate of Sousse, twig dieback and fruit rots were observed on several trees. Symptoms noted on most-known cultivars in Tunisia cvs. Gabsi and Kalai, were characterized by the presence of cankers and abundant, black, and solitary pycnidia on diseased twigs and shoots associated with marginal leaf browning, resulting in the dieback of one or multiple branches. On fruits, symptoms of dry rot and fruit mummifcation were frequently observed and decayed fruits were covered by large black pycnidia. Tese symptoms have been described in previous works as being associated with the presence of Coniella granati Saccardo (an obligate synonym of Pilidiella granati according to MycoBank database). Tis pathogen has been reported to be responsible for dieback and twig blight of pomegranate trees, fruit dry rot and/or crown rot, in many countries including China, India, Iran, Mexico, America, Greece, Turkey, Spain, and Italy [10,18- 25] and to cause substantial economic loss to pomegranate industry. Coniella granati (Saccardo) a New Potential Threat to Pomegranate (Punica granatum L.) in Tunisia Causing Twig Dieback and Fruit Rot Hayfa Jabnoun-Khiareddine 1 *, Nesrine Ibrahim 2 , Rania Aydi Ben Abdallah 1 , Messaoud Mars 3 , Zeinab Kthiri 4 and Mejda Daami-Remadi 1 1 UR13AGR09-Integrated Horticultural Production in the Tunisian Centre-East, Regional Research Centre on Horticulture and Organic Agriculture, University of Sousse, Chott-Mariem, Tunisia 2 Higher Agronomic Institute of Chott-Mariem, University of Sousse, 4042, Chott-Mariem, Tunisia 3 UR13AGR05-Agrobiodiversity, Higher Agronomic Institute, Chott-Mariem, IRESA-University of Sousse, Tunisia 4 National Agronomic Institute of Tunisia, 1082, Tunis, University of Carthage, Tunisia Abstract The disease caused by Coniella granati (Saccardo) (syn. Pilidiella granati, Saccardo) is an expanding threat to pomegranate (Punica granatum L.) cultivation and industry and is rapidly emerging in almost all pomegranate- producing regions of the world. The current study presents the frst attempt to characterize C. granati associated with pomegranate dieback, shoot blight and fruit rot in Tunisia. Pathogenic isolates were identifed based on their cultural and morphological characteristics and molecular data. Collected C. granati isolates were shown able to grow between 10°C and 30°C with an optimal mycelial growth at 20-25°C but they did not grow at 35°C. The fungus was able to grow 4-10 pH with an optimum growth at pH 4-5 for Cg1 and Cg2 isolates. Potato Dextrose Agar (PDA), Carrot Agar (CA) and Oatmeal Agar (OA) followed by pomegranate juice agar (PJA) and Malt Extract Agar (MEA) favored its mycelial growth. Pathogen growth was reduced under continuous light in comparison with the 12 h light/12 h dark regime and was signifcantly slowest under 24 h dark regime. Inoculated to pomegranate cv. Gabsi fruits, C. granati isolates induced soft rot within 9 days following incubation at 25°C and a complete fruit rot after 15 days. Leaves were highly susceptible to C. granati infection and completely degenerated 5 days post-inoculation. C. granati isolates were found to be pathogenic on pomegranate cv. Gabsi attached shoots and detached branches, giving rise to brown necrotic lesions. Keeping in view the importance of the pomegranate crop and the destructive nature of Coniella induced disease, further studies are needed to verify the pathogen host range, its aggressiveness towards the mostly grown Tunisian pomegranate varieties and to search for suitable control methods. *Corresponding author: Jabnoun-Khiareddine H, UR13AGR09-Integrated Horticultural Production in the Tunisian Centre-East, Regional Research Centre on Horticulture and Organic Agriculture, University of Sousse, Chott-Mariem, Tunisia, Tel: 0021673327543, E-mail: jkhayfa@yahoo.fr Received July 09, 2018; Accepted September 19, 2018; Published September 25, 2018 Citation: Jabnoun-Khiareddine H, Ibrahim N, Aydi Ben Abdallah R, Mars M, Kthiri Z, et al. (2018) Coniella granati (Saccardo) a New Potential Threat to Pomegranate (Punica granatum L.) in Tunisia Causing Twig Dieback and Fruit Rot. J Plant Pathol Microbiol 9: 450. doi: 10.4172/2157-7471.1000450 Copyright: © 2018 Jabnoun-Khiareddine H, et al. 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