University of Maryland, Department of Entomology, 4112 Plant Sciences Building, College Park, MD 20742, USA.
Fungal Genet Biol. 2010 Jul;47(7):602-7. doi: 10.1016/j.fgb.2010.03.011. Epub 2010 Apr 9.
Insect pathogenic fungi including Metarhizium anisopliae offer an environmentally friendly alternative to chemical pesticides. However, their use has been limited by their relatively slow killing speed compared to chemicals and low tolerance to abiotic stresses. We report here on a class 1 laccase (MLAC1) that is involved in both virulence and tolerance to environmental stresses. Mlac1 is expressed during isotropic growth (swelling) but not during polarized growth (e.g., germ tubes and hyphae); Mlac1 is therefore expressed exclusively in the later stages of conidiation and in blastospores when M. anisopliae is living as a saprophyte. During infection processes, Mlac1 is also expressed by appressoria (infection structures) on the cuticle surface and hyphal bodies inside the insect haemocoel. Disrupting Mlac1 reduced virulence to caterpillars because of impaired appressoria and delayed post-infection events. It also produced a yellow-conidia phenotype with increased conidial susceptibility to heat shock (45 degrees C for 2h) and UV-B stress. The relationship between M. anisopliae's pigment-synthesis pathway and its adaptation to diverse natural habitats is discussed.
昆虫病原真菌包括绿僵菌，为化学农药提供了一种环保的替代品。然而，与化学农药相比，它们的致死速度相对较慢，对非生物胁迫的耐受性也较低，这限制了它们的应用。我们在这里报告了一种参与毒力和环境胁迫耐受的 1 类漆酶（MLAC1）。Mlac1 在各向同性生长（肿胀）期间表达，但不在极性生长（例如，芽管和菌丝）期间表达；因此，Mlac1 仅在分生孢子形成的后期以及绿僵菌作为腐生物生活时的芽孢子中表达。在感染过程中，Mlac1 也在表皮表面的附着胞（感染结构）和昆虫血腔内部的菌丝体中表达。破坏 Mlac1 会降低对毛毛虫的毒力，因为附着胞受损，感染后的事件也会延迟。它还产生了一种黄分生孢子表型，使分生孢子对热休克（45°C 持续 2 小时）和 UV-B 应激的敏感性增加。讨论了绿僵菌的色素合成途径与其适应不同自然栖息地之间的关系。
