RESUMO
Saccharopine dehydrogenase (EC 1.5.1.7) regulates the last step of fungal lysine biosynthesis. The gene (Fvsdh) encoding saccharopine dehydrogenase was identified and cloned from the whole genome of Flammulina velutipes. The genomic DNA of Fvsdh is 1257 bp, comprising three introns and four exons. The full-length complementary DNA of Fvsdh comprises 1107 bp with a deduced amino acid sequence of 368 residues. A 1,000-bp promoter sequence containing the TATA box, CAAT box, and several putative cis-acting elements was also identified. The results of tissue expression analysis showed that the expression level of the Fvsdh gene was higher in the pileus than in the stipe whether in the elongation or maturation stage. Further research showed that the lysine contents were 3.03 and 2.95 mg/g in maturation-pileus and elongation-pileus, respectively. In contrast, the lysine contents were 2.49 and 2.07 mg/g in elongation-stipe and maturation-stipe, respectively. To study the function of Fvsdh, we overexpressed Fvsdh in F. velutipes and found that Fvsdh gene expression was increased from 1.1- to 3-fold in randomly selected transgenic strains. The lysine contents were also increased from 1.12- to 1.3-fold in these five transformants, except for strain T3, in which the lysine contents were the same as the control. These results indicate that the expression of the Fvsdh gene can affect the lysine content of F. velutipes.
Assuntos
Flammulina/genética , Flammulina/metabolismo , Proteínas Fúngicas/genética , Lisina/biossíntese , Sacaropina Desidrogenases/genética , Sequência de Bases , Vias Biossintéticas/genética , Clonagem Molecular , Flammulina/classificação , Flammulina/crescimento & desenvolvimento , Proteínas Fúngicas/metabolismo , Expressão Gênica , Regulação Fúngica da Expressão Gênica , Filogenia , Regiões Promotoras Genéticas , Sacaropina Desidrogenases/metabolismoRESUMO
Flammulina velutipes is one of the mushrooms produced most widely in East Asia. In this study we investigated phenotypic variations of 7 agronomic traits in 37 F. velutipes strains from China, and we analyzed their genetic diversity with 70 simple sequence repeat markers. The Shannon information index and gene diversity were 0.894 and 0.478, respectively, demonstrating high genetic variation among the tested strains. Poor genetic variation was found among white strains, in contrast to yellow ones. Analysis of population structure resolved 2 unambiguous genetic groups in the tested F. velutipes strains, with little differentiation between them (FST = 0.016). Yellow cultivars possibly originated from indigenous wild strains in southwest China. Phenotypic correlations were identified among the 7 traits. In particular, stipe length (SL) was significantly positively correlated with yield, indicating that SL could be used as an index for breeding high-yield strains. The 2 genetic groups, and white strains and yellow ones, showed significant differences between SL, yield, and the time interval (days) from mycelial scratch to formation of the first fruiting body. These results indicate that these 3 traits were stratified by population structure. Detection of genetic and phenotypic variations would lay the groundwork for further breeding of elite F. velutipes strains.
Assuntos
Flammulina/química , Flammulina/genética , Variação Genética , Fenótipo , China , Análise por Conglomerados , Flammulina/classificação , Carpóforos/ultraestrutura , Frequência do Gene , Desequilíbrio de Ligação , Repetições de Microssatélites/genética , Micélio/crescimento & desenvolvimento , Pigmentação , Polimorfismo GenéticoRESUMO
The laccase activities of 13 strains of medicinal and edible mushrooms from the Flammulina genus (F. velutipes, F. rossica, and F. fennae) were studied. The effects of both fungal isolates and culture media were investigated. The laccase activities indicated significant differences among Flammulina strains (P < 0.001), and the cultural media significantly affected the laccase activities in Flammulina spp. (P < 0.001). The morphological characteristics of the 3 Flammulina species were similar, but differences in phylogenetic analysis and laccase activity existed among different species. Although isolates of each Flammulina species differed, the laccase variables among different Flammulina species were greater than those within the same species. The presence of simple carbon and nitrogen sources increased the maximum laccase enzyme activity, but the occurrence of both laccase activity and maximum laccase enzyme activity was delayed compared with lignocellulosic material. The laccase activities of most Flammulina isolates were increased when exposed to copper ions. Our findings offer insights into laccase productivity in response to different Flammulina species or strains and different submerged fermentation treatments.