Departamento de Bioquímica e Biologia Molecular, Universidade Federal de Goiás (ICB II), Campus Samambaia, Instituto de Ciências Biológicas, CEP 74001-970, Goiânia, GO, Brasil.
Laboratório de Microbiologia, Universidade Federal do Tocantins, 77500-000, Porto Nacional, TO, Brasil.
Microbiol Res. 2019 Dec;229:126326. doi: 10.1016/j.micres.2019.126326. Epub 2019 Aug 26.
Sclerotinia sclerotiorum (Lib.) de Bary produces a resistance structure called sclerotium, which guarantees its survival in soil for long periods. Morphological and melanization aspects during sclerotial development were evaluated by microscopy and qRT-PCR techniques. S. sclerotiorum produces sclerotia with different phases of maturation and melanization during growth in PDA medium. Using scanning electron microscopy we observed that there are no structural differences in the three stages of formation of melanized and non-melanized sclerotium. Through histochemical analysis we observed that the melanized sclerotium accumulates more glycogen and produces less protein than non-melanized sclerotia. Melanin was most commonly found in the rind of melanized sclerotia, and the highest concentration of lipofucsins was found in non-melanized sclerotia. These molecules are products of the lipid peroxidation pathway and are associated with oxidative stress during differentiation in fungi. The expression of histidine kinase (shk) and adenylate cyclase (sac) genes in melanized and non-melanized sclerotiawere also evaluated. The higher gene expression of shk and lesser expression of sac in non-melanized sclerotiais an indication of the participation of cell signaling in the development of these structures. The higher expression of polyketide synthase (pks), tyrosinase (tyr) and laccase (lac) in non-melanized sclerotia suggested that S. sclerotiorum can use the DHN and L-dopa pathways to produce melanin. Expression studies of the enzymes chitin synthase and glucan synthase suggest that this process occurs along with the formation of melanin. This is interesting since polysaccharides, such as chitin and β-1,3-glucan, serve as a scaffold to which the melanin granules are cross-linked.
核盘菌（Sclerotinia sclerotiorum）（Lib.）de Bary 产生一种称为菌核的抗性结构，可确保其在土壤中长期存活。通过显微镜和 qRT-PCR 技术评估了菌核发育过程中的形态和黑化方面。核盘菌在 PDA 培养基中生长时，会产生具有不同成熟和黑化阶段的菌核。通过扫描电子显微镜观察，我们发现三个阶段形成的有黑和非黑化菌核在结构上没有差异。通过组织化学分析，我们观察到黑化菌核积累的糖原比非黑化菌核多，产生的蛋白质少。黑色素最常见于黑化菌核的外皮中，而非黑化菌核中则发现最高浓度的脂褐素。这些分子是脂质过氧化途径的产物，与真菌分化过程中的氧化应激有关。还评估了黑化和非黑化菌核中组氨酸激酶（shk）和腺苷酸环化酶（sac）基因的表达。非黑化菌核中 shk 基因的高表达和 sac 基因的低表达表明细胞信号转导参与了这些结构的发育。非黑化菌核中聚酮合酶（pks）、酪氨酸酶（tyr）和漆酶（lac）的高表达表明 S. sclerotiorum 可以使用 DHN 和 L-多巴途径来产生黑色素。几丁质合酶和葡聚糖合酶的表达研究表明，这个过程伴随着黑色素的形成。这很有趣，因为多糖，如几丁质和β-1,3-葡聚糖，作为黑色素颗粒交联的支架。
