CHAPTER 2 LITERATURE REVIEW 2.1 Introduction of fungi Fungi are one of the most diverse life from on earth and predicting number of fungal species is considered important among mycologists (Hyde, 2001). Fungi are a group of organism that are classified within their own kingdom, the fungal kingdom, as they are neither plants nor animals. The fungi are fact, an ancient lineage that first appear in the fossil recode as spores in conjunction with the first appearance of land plants, about 500450 million years ago (Cairney, 2000). Fungi are eukaryotic and heterotrophic, lacking chlorophyll (Moncalvo, 2005). Most of fungi have an alternating haploid/diploid lifecycle, as seen in other sexual organism, but they also have an anamorphic lifecycle that persists without sexual recombination (Bidochka and De Koning, 2001). Most fungi are saprobic living on dead organic matter, in the soil or as pathogens and endophytes of plant and animal. The six fungal phyla accepted include the Ascomycota, Basidiomycota, Chytridiomycota, Glomeromycota, Microsporidia and Zygomycota (Kirk et al., 2008). Currently about 80,060 species are known. Rossman (1994) estimated the number of fungal species in the world was just over 1 million (Table 2.1) based on information in the US National Fungus Collection database, an All Taxon Biodiversity Inventory (ATBI) of tropical site, and the literature. Recent studies suggested that fungal diversity is greater in the tropics than in temperate regions, and might prove to be hyper-diverse, 7 and as a consequence 1.5 million species will eventually be discovered (Fröhlich and Hyde, 1999; Arnold et al., 2000). Table 2.1 Major groups of fungi and estimated world species number (Rossman, 1994). Group Estimated species world-wide Well-known Aphyllophorales 20000 Macrolichens 20000 Moderately well-known Agaricales 80000 Dematiaceous and aquatic hyphomycetes 80000 Uredinales 50000 Hypocreales and Xylariales 50000 Ustilaginales 15000 Gasteromycetes 10000 Erysiphales 10000 Jelly fungi 5000 Pezizales 3000 Myxomycetes 1500 Endomycetales (true yeasts) 1000 Poorly known Non-dematiaceous hyphomycetes 200000 Coelomycetes 200000 Other perithecioid ascomycetes 100000 Helotiales 70000 Insect-specific fungi 50000 Crustose lichens 20000 Mucorales 20000 Oomycetes 20000 Chytridiomycetes 20000 Endogonales and Glomales 1000 Total 1028500 2.2 Fungi in Thailand Thailand is a country that includes a rich diversity of habitats, including, coral reefs, mangrove forest, limestone outcrops, deciduous forest, tropical rainforests and pine tree forest, but lagged behind with respect to research on biodiversity of its fungi (Jones 8 and Hyde, 2004; Tanticharoen, 2004). It’s geographical position in the tropics and climatic variation support a biological divers flora and fauna (Gray et al., 1994). Before 1990, reports on fungal diversity in Thailand were sporadic, and knowledge of Thailand’s fungal diversity was very poor. Tanticharoen (2004) reported that 15,000 flowering plants, 1,000 orchids, 600 ferns and more than 1,000 endemic vascular plant species have been recorded for Thailand. Moreover, the number of fungal records in Thailand has increased from 700 species (in 1990) to over 3,300 species in 2013 according to the database of BIOTEC (http://www.biotec.or.th/bcc/cat_fungi.asp) and indicated that the total number of fungi in Thailand may be higher with than 6,000 species (Jones and Hyde, 2004). The number of new fungi to science have been described from Thailand e.g. Acrodictys micheliae (Kodsueb et al., 2007), Amanita siamensis (Sanmee et al., 2003), Astraeus odoratus (Prosri et al., 2004), Ascothailandia grenadoidia (Sri-indrasutdhi et al., 2010), Candida krabiensis, C. sithepensis, C. thaimueangensis, Kazachstania siamensis, Ogataea nakhonphanomensis, Pichia thermomethanolica, Torulaspora maleeae, (Limtong et al., 2004, 2005, 2007a, 2007b, 2007c, 2008), C. xylanilytica (Boonmak et al., 2011), Craspedodidymum licualae, Cr. microsporum, Cr. siamense (Pinruan et al., 2004), Cheiromyces magnoliae (Promputtha et al., 2005), Dictyosporium muase (Photita et al., 2002), Gaeumannomyces amomi (Bussaban et al., 2001a), Lactarius formosus L. friabilis, L. lavandulus (Le et al., 2007a, 2007b, 2007c), Leiosphaerella amomi (Bussaban et al., 2001a), Linocarpon lamiae, Li. siamensis, Li. suthepensis (Thongkantha et al., 2003), Ophioceras chiangdaoense (Thongkantha et al., 2008), Pyricularia kookicola, P. longispora, P. variabilis (Bussaban et al., 2003a), 9 Stachybotrys suthepensis (Photita et al., 2003), Tortulomyces thailandicus, Nitschkia siamensis (Vasilyeva et al., 2013), Xenosporium amomi (Bussaban et al., 2003b) and Talaromyces thailandensis, T. tratensis (Manoch et al., 2013). From 2006 to 2013, many publication on microfungi communities from various plants in tropical area have been described from Thailand e.g. bamboo culms (Choeyklin et al., 2009), grasses (Bhilabutra et al., 2010), leaf litter (Wang et al., 2008), palms (Pinruan et al., 2007, 2010a, 2010b; Pinnoi et al., 2006, 2007, 2009, 2010; Lumyong et al., 2009), teak (Chareprasert et al., 2006), wood (Vasilyeva et al., 2013; Kodsueb et al., 2006, 2007. 2008a, b), freshwater fungi (Sri-indrasutdhi et al., 2010; Zhang et al., 2011), marine fungi (Pilantannapak et al., 2006; Jones et al., 2006, 2009; Dethoup and Manoch, 2009). In addition, macrofungi have been studies in Thailand e.g. Agaricus (Zhao et al., 2011; Wisitrassameewong et al., 2012), Amanita (Sanmee et al., 2008), Boletes (Seehanan and Petcharat, 2008; Thongklam, 2008; Pukahuta et al., 2009; Kumla et al., 2012), Lactarius (Le et al., 2007a, 2007b, 2007c), Lentinus (Karunarathna et al., 2011) and Marasmius (Wannathes et al., 2009). 2.3 Endophytic fungi 2.3.1 Definition of endophytes There have been many definitions of what an endophyte (Table 2.2), with that by Petrini (1991), generally accepted. The “balanced antagonism” hypothesis was initially proposed to address how a fungal endophyte avoids activation the host plant defense and manages to grown within its host without causing visible manifestations of infection or 10 disease (Schulz and Boyle, 2005; Arnold, 2008). This hypothesis proposed that asymptomatic colonization is the balance of antagonisms between the host plant and fungal endophyte (Figure 2.1A). Table 2.2 Definitions of what constitutes an endophyte (Hyde and Soytong, 2008). Year Definition Reference 1866 Any organisms occurring within plant tissues De Bary, 1866 1971 An organism that lives in another organism Ainsworth, 1971 1986 Mutualists, those fungi that colonize aerial parts of living Carroll, 1986 plant tissues and do not cause symptoms of disease 1988 Fungi that form unapparent infections within leaves and Carroll, 1998 stem of healthy plans 1991 All organisms inhabiting plant organs that at some time in Petrini, 1991 their life, can colonize internal plant tissues without causing apparent harm to the host 1992 A group that colonize living, internal tissues of plants Hirsch and Braun, 1992 without causing any immediate, overt negative effects 1993 Fungi as colonizers of the living internal tissues of their Rollinger and Langenheim, 1993 plant host 1993 Endophytes are any fungi isolated from internal symtomless Cabral et al., 1993 plant tissues 1995 Fungi and bacteria which, for all or part of their life cycle, Wilson, 1995 invade the tissues of living plants and cause unapparent and asymptomatic infections entirely within plant tissues, but cause no symptoms of disease 1995 Infection strategy is regarded as important in the definition Wilson, 1995 of the term of endophyte 2000 True endophyte-fungi whose colonization never results in Mostert et al., 2000 visible disease symptoms 2005 Fungi that colonize a plant without causing visible disease Schulz and Boyle, 2005 symptoms at any specific moment Endophytes and pathogens both possess many virulence factors that are countered by plant defense mechanisms. If fungal virulence and plant defense are balanced, the association remains apparently asymptomatic and avirulence. In addition, if the plant defense mechanisms completely counteract the fungal virulence factors, the fungus will perish. Conversely, if the plant succumbs to the virulence of the fungus, a plant-pathogen 11 relationship would lead to plant disease (Figure 2.1B). The interaction between host and endophyte is balanced or imbalance depened on the general status of the partner, virulence of the fungus, the defenses of the host plant, and both virulence and defense being variable and influenced by environmental factors (Kogel et al., 2006). Many endophytes could possibly be latent pathogens, they might be influenced by certain intrinsic or environmental factors to express factors that lead to pathogenicity (Schulz and Boyle, 2005; Arnold, 2008). There are numerous examples of endophytes that become pathogens. Mostert et al. (2000) and Romero et al. (2001) reported that most fungi isolated as endophyte such as, Alternaria alternata, Fusarium sp., Phoma subglomerata, Phomopsis viticola also grow and sporulate on chlorotic and necrotic leaf tissues of host plant. Photita et al. (2004) reported that some fungal endophytes of wild banana were able to cause leaf spots in living banana leaves. Recently, Begoude et al. (2010) found that the Botryosphaeriaceae are endophytic fungi and latent pathogens that can result in wood stain, cankers, die-back and death of trees, particularly when trees are under stress. Endophytic fungi not only occur in living tissues but also in decomposing tissues as saprobes