Transcriptome Reveals Roles of Lignin-Modifying Enzymes and Abscisic Acid in the Symbiosis of Mycena and Gastrodia elata

The role of symbiotic fungi in the life cycle of Gastrodia elata Blume (Orchidaceae): a comprehensive review

Gastrodia elata Blume, a fully mycoheterotrophic perennial plant of the family Orchidaceae, is a traditional Chinese herb with medicinal and edible value. Interestingly, G. elata requires symbiotic relationships with Mycena and Armillaria strains for seed germination and plant growth, respectively. However, there is no comprehensive summary of the symbiotic mechanism between fungi and G. elata. Here, the colonization and digestion of hyphae, the bidirectional exchange of nutrients, the adaptation of fungi and G. elata to symbiosis, and the role of microorganisms and secondary metabolites in the symbiotic relationship between fungi and G. elata are summarized. We comprehensively and deeply analyzed the mechanism of symbiosis between G. elata and fungi from three perspectives: morphology, nutrition, and molecules. The aim of this review was to enrich the understanding of the mutualistic symbiosis mechanisms between plants and fungi and lay a theoretical foundation for the ecological cultivation of G. elata.

The RING-H2 gene LdXERICO plays a negative role in dormancy release regulated by low temperature in Lilium davidii var. unicolor

Dormancy regulation is the basis of the sustainable development of the lily industry. Therefore, basic research on lily dormancy is crucial for innovation in lily cultivation and breeding. Previous studies revealed that dormancy release largely depends on abscisic acid (ABA) degradation. However, the key genes and potential regulatory network remain unclear. We used exogenous ABA and ABA inhibitors to elucidate the effect of ABA on lily dormancy. Based on the results of weighted gene coexpression network analysis (WGCNA), the hub gene LdXERICO was identified in modules highly related to endogenous ABA, and a large number of coexpressed genes were identified. LdXERICO was induced by exogenous ABA and expressed at higher levels in tissues with vigorous physiological activity. Silencing LdXERICO increased the low-temperature sensitivity of bulblets and accelerated bulblet sprouting. LdXERICO rescued the ABA insensitivity of xerico mutants during seed germination in Arabidopsis, suggesting that it promotes seed dormancy and supporting overexpression studies on lily bulblets. The significant increase in ABA levels in transgenic Arabidopsis expressing LdXERICO indicated that LdXERICO played a role by promoting ABA synthesis. We generated three transgenic lines by overexpressing LdICE1 in Arabidopsis thaliana and showed that, in contrast to LdXERICO, LdICE1 positively regulated dormancy release. Finally, qRT-PCR confirmed that LdXERICO was epistatic to LdICE1 for dormancy release. We propose that LdXERICO, an essential gene in dormancy regulation through the ABA-related pathway, has a complex regulatory network involving temperature signals. This study provides a theoretical basis for further exploring the mechanism of bulb dormancy release.

The genome and transcriptome of Sarocladium terricola provide insight into ergosterol biosynthesis

Sarocladium terricola is a species of ascomycete fungus that has been recognized as a biocontrol agent for managing animal and plant pathogens, and exhibits significant potential as a feed additive. In this study, we utilized a combination of short-read Illumina sequencing and long-read PacBio sequencing to sequence, assemble, and analyze the genome of S. terricola. The resulting genome consisted of 11 scaffolds encompassing 30.27 Mb, with a GC content of 54.07%, and 10,326 predicted protein coding gene models. We utilized 268 single-copy ortholog genes to reconstruct the phylogenomic relationships among 26 ascomycetes, and found that S. terricola was closely related to two Acremonium species. We also determined that the ergosterol content of S. terricola was synthesized to nearly double levels when cultured in potato dextrose media compared to bean media (4509 mg/kg vs. 2382 mg/kg). Furthermore, transcriptome analyses of differentially expressed genes suggested that the ergosterol synthesis genes ERG3, ERG5, and ERG25 were significantly up-regulated in potato dextrose media. These results will help us to recognize metabolic pathway of ergosterol biosynthesis of S. terricloa comprehensivelly.