Fungal endophyte diversity in the leaves of the medicinal plant Myracrodruon urundeuva in a Brazilian dry tropical forest and their capacity to produce L-asparaginase

ABSTRACT We studied the fungal endophyte community of the leaves of Myracrodruon urundeuva in Brazil along with their potential to produce L-asparaginase. In total, 187 endophytes were isolated. The colonization rate of leaf fragments from caatinga (10.41 %) was lower than those from brejo de altitude (39.58 %). Sequences of ITS rDNA from all endophytes revealed relationships with Ascomycota (Botryosphaeriales, Chaetothyriales, Diaporthales, Eurotiales, Glomerellales, Hypocreales, and Pleosporales) and Basidiomycota (Polyporales). The most frequent endophytes were members of the genus Diaporthe. Talaromyces was an indicator genus for caatinga while Phyllosticta, Diaporthe, and Colletotrichum were for brejo de altitude. The composition of endophytic fungi in caatinga and brejo de altitude differed significantly, its richness and diversity (H' = 3.41) being significantly higher in brejo de altitude. Diaporthe sp. URM 7793 was the best producer of L-asparaginase (2.41 U/g), followed by Diaporthe sp. URM 7779 (2.00 U/g), Talaromyces sp. URM 7785 (1.91 U/g), and Diaporthe sp. URM 7792 (1.47 U/g). The composition of endophytic fungi assemblages is strongly influenced by the type of ecosystem. In its natural habitat, M. urundeuva harbors an important diversity of endophytes, which could be used to produce L-asparaginase.

【摘要】本研究针对巴西乌仑杜漆（Myracrodruon urundeuva）叶片的真菌内生菌群落展开调查，并探究其产生L-天冬酰胺酶（L-asparaginase）的潜力。研究共分离得到187株内生真菌。卡廷加（caatinga）生境下叶片片段的定殖率（10.41%）低于高海拔湿地林（brejo de altitude）生境（39.58%）。对所有内生真菌的ITS核糖体DNA（ITS rDNA）序列进行分析后发现，其类群涵盖子囊菌门（Ascomycota）的葡萄座腔菌目（Botryosphaeriales）、小煤炱目（Chaetothyriales）、间座壳目（Diaporthales）、散囊菌目（Eurotiales）、丛赤壳目（Glomerellales）、肉座菌目（Hypocreales）及格孢菌目（Pleosporales），以及担子菌门（Basidiomycota）的多孔菌目（Polyporales）。最优势的内生真菌类群为拟茎点霉属（Diaporthe）成员。塔拉氏霉属（Talaromyces）为卡廷加生境的指示属，而叶点霉属（Phyllosticta）、拟茎点霉属（Diaporthe）及炭疽菌属（Colletotrichum）为高海拔湿地林生境的指示属。卡廷加与高海拔湿地林生境的内生真菌群落组成存在显著差异，且高海拔湿地林生境的内生真菌丰富度与多样性（香农威纳指数H'=3.41）显著更高。产酶能力测试结果显示，拟茎点霉属菌株URM 7793的L-天冬酰胺酶产量最高，达2.41 U/g，其次依次为拟茎点霉属菌株URM 7779（2.00 U/g）、塔拉氏霉属菌株URM 7785（1.91 U/g）及拟茎点霉属菌株URM 7792（1.47 U/g）。研究表明，内生真菌群落组成受生态系统类型的影响显著。乌仑杜漆在其自然生境中蕴藏着具有重要开发价值的内生真菌多样性，此类内生真菌可用于L-天冬酰胺酶的生产。