Paixão Flávia R S, Huarte-Bonnet Carla, Ribeiro-Silva Cárita de S, Mascarin Gabriel M, Fernandes Éverton K K, Pedrini Nicolás
Instituto de Investigaciones Bioquímicas de La Plata, Centro Científico Tecnológico La Plata Consejo Nacional de Investigaciones Científicas y Técnicas-Universidad Nacional de La Plata, La Plata, Argentina.
Instituto de Patologia Tropical e Saúde Pública, Universidade Federal de Goiás, Goiânia, Brazil.
Front Fungal Biol. 2021 Apr 30;2:654737. doi: 10.3389/ffunb.2021.654737. eCollection 2021.
species fungi are able to produce resistant structures termed microsclerotia, formed by compact and melanized threads of hyphae. These propagules are tolerant to desiccation and produce infective conidia; thus, they are promising candidates to use in biological control programs. In this study, we investigated the tolerance to both ultraviolet B (UV-B) radiation and heat of microsclerotia of strain ARSEF 2575. We also adapted the liquid medium and culture conditions to obtain mycelial pellets from the same isolate in order to compare these characteristics between both types of propagules. We followed the peroxisome biogenesis and studied the oxidative stress during differentiation from conidia to microsclerotia by transmission electron microscopy after staining with a peroxidase activity marker and by the expression pattern of genes potentially involved in these processes. We found that despite their twice smaller size, microsclerotia exhibited higher dry biomass, yield, and conidial productivity than mycelial pellets, both with and without UV-B and heat stresses. From the 16 genes measured, we found an induction after 96-h differentiation in the oxidative stress marker genes , and ; the peroxisome biogenesis factors and ; and the photoprotection genes and ; and . We concluded that an oxidative stress scenario is induced during microsclerotia differentiation in and confirmed that because of its tolerance to desiccation, heat, and UV-B, this fungal structure could be an excellent candidate for use in biological control of pests under tropical and subtropical climates where heat and UV radiation are detrimental to entomopathogenic fungi survival and persistence.
某些真菌物种能够产生称为微菌核的抗性结构，这些结构由紧密且黑色素化的菌丝形成。这些繁殖体耐干燥并产生感染性分生孢子；因此，它们是生物防治计划中很有前景的候选对象。在本研究中，我们调查了ARSEF 2575菌株微菌核对紫外线B（UV-B）辐射和热的耐受性。我们还调整了液体培养基和培养条件，以从同一分离物中获得菌丝球，以便比较这两种繁殖体的这些特性。我们追踪了过氧化物酶体的生物发生过程，并在用过氧化物酶活性标记染色后通过透射电子显微镜以及通过可能参与这些过程的基因的表达模式，研究了从分生孢子到微菌核分化过程中的氧化应激。我们发现，尽管微菌核的大小只有菌丝球的一半，但无论有无UV-B和热胁迫，微菌核的干生物量、产量和分生孢子生产率都高于菌丝球。在所检测的16个基因中，我们发现在96小时分化后，氧化应激标记基因、过氧化物酶体生物发生因子和光保护基因、以及有诱导表达。我们得出结论，在微菌核分化过程中诱导了氧化应激情况，并证实由于其对干燥、热和UV-B的耐受性，这种真菌结构可能是热带和亚热带气候下害虫生物防治的极佳候选对象，在这些气候条件下，热和紫外线辐射对昆虫病原真菌的存活和持久性不利。
