2007), and were selleckchem therefore designated as saprophytes and endophytes, respectively. In the rubber tree, C. cassiicola has thus far been exclusively known as a necrotrophic pathogen that causes the Corynespora Leaf Fall (CLF) disease, which ranks among the most important fungal diseases in Asian and African rubber plantations. Initially, C. cassiicola was described as a minor pathogen capable of attacking
only budwood or seedling nursery plants (Newsam 1960; Chee 1988), but in 1975, the first epidemic outbreak on a plantation scale occurred in Indonesia. In the 1980s, several other countries in Southeast Asia were severely affected by disease outbreaks and thousands of hectares of rubber trees were uprooted in Malaysia, Indonesia, Thailand and Sri Lanka (Liyanage et al. 1986; Pongthep 1987; Chee 1988). By the end of the 1980s, African countries were also affected by CLF. The disease severity further increased until several important rubber tree cultivars considered to be tolerant or resistant to CLF during the first epidemic in the mid 1980s succumbed to the disease (Jayasinghe and Silva 1996; Shamsul and Shamsuri selleck compound 1996; Sinulingga et al. 1996; Wahounou et al. 1996). Currently, all Asian and African rubber-producing countries, which account for 98 % of the
natural rubber production in the world (94 and 4 % for each continent, respectively), are affected by the disease resulting in considerable economic losses. CLF is characterized by necrotic lesions that develop on both young and mature leaves and lead to extensive defoliation. The fungus typically causes areas of necrosis with a fish bone appearance due to the darkening of the veins adjacent to the lesions (Chee 1988; Liyanage and Liyanage 1986; Pongthep 1987). However, the symptoms vary depending on the age, type and location of the rubber tree (Jayasinghe et al. 1998). This symptom variability impedes diagnosis of the disease in a plantation. Additionally, C. cassiicola isolates within the same agroclimatic zone vary widely in morphology, colony color, growth, spore production, pathogenicity and
genetic diversity (Darmono et al. 1996; Jayasinghe and Silva 1996; Breton et al. 2000; Atan and Hamid 2003; Alanine-glyoxylate transaminase Romruensukharom et al. 2005; Dixon et al. 2009; Qi et al. 2009). Colonization of the rubber tree tissues by C. cassiicola involves the secretion of phytotoxic molecules (Onesirosan et al. 1975; Liyanage and Liyanage 1986; Purwantara 1987; Nugawela et al. 1989; Breton et al. 2000). A toxin called cassiicolin was purified and characterized from the culture filtrate of a rubber tree isolate (CCP) from the Philippines (Breton et al. 2000; Barthe et al. 2007; de Lamotte et al. 2007). The toxin is a small, secreted glycosylated protein that plays an important role in C. cassiicola pathogenicity. The cassiicolin-encoding gene encodes a precursor protein containing a signal peptide at the amino terminus that is predicted to target the protein for secretion (Déon et al. 2012).