Interspecific hybridization is a primary cause of extensive morphological and chromosomal variation and plays an important role in plant species diversification. However, the role of interploidal hybridization in the formation of hybrid swarms is less clear. Epidendrum encompasses wide variation in chromosome number and lacks strong premating barriers, making the genus a good model for clarifying the role of chromosomes in postzygotic barriers in interploidal hybrids. In this sense, hybrids from the interploidal sympatric zone between E. fulgens (2n = 2x = 24) and E. puniceoluteum (2n = 4x = 56) were analyzed using cytogenetic techniques to elucidate the formation and establishment of interploidal hybrids. Hybrids were not a uniform group: two chromosome numbers were observed, with the variation being a consequence of severe hybrid meiotic abnormalities and backcrossing with E. puniceoluteum. The hybrids were triploids (2n = 3x = 38 and 40) and despite the occurrence of enormous meiotic problems associated with triploidy, the hybrids were able to backcross, producing successful hybrid individuals with broad ecological distributions. In spite of the nonpolyploidization of the hybrid, its formation is a long-term evolutionary process rather than a product of a recent disturbance, and considering other sympatric zones in Epidendrum, these events could be recurrent.

The largest living rodent, capybara, can efficiently depolymerize and utilize lignocellulosic biomass through microbial symbiotic mechanisms yet elusive. Herein, we elucidate the microbial community composition, enzymatic systems and metabolic pathways involved in the conversion of dietary fibers into short-chain fatty acids, a main energy source for the host. In this microbiota, the unconventional enzymatic machinery from Fibrobacteres seems to drive cellulose degradation, whereas a diverse set of carbohydrate-active enzymes from Bacteroidetes, organized in polysaccharide utilization loci, are accounted to tackle complex hemicelluloses typically found in gramineous and aquatic plants. Exploring the genetic potential of this community, we discover a glycoside hydrolase family of β-galactosidases (named as GH173), and a carbohydrate-binding module family (named as CBM89) involved in xylan binding that establishes an unprecedented three-dimensional fold among associated modules to carbohydrate-active enzymes. Together, these results demonstrate how the capybara gut microbiota orchestrates the depolymerization and utilization of plant fibers, representing an untapped reservoir of enzymatic mechanisms to overcome the lignocellulose recalcitrance, a central challenge toward a sustainable and bio-based economy.

Glycoside hydrolases (GHs) are enzymes found in all living kingdoms that are involved in multiple physiological functions. Due to their multiple enzymatic activities, GHs are broadly applied in bioethanol, food, and paper industry. In order to increase the productivity of these industrial processes, a constant search for novel and efficient enzymes has been proved to be necessary. In this context, metagenomics is a powerful approach to achieve this demand. In the current study, we describe the discovery and characterization of a novel member of GH16 family derived from the sugarcane soil metagenome. The enzyme, named SCLam, has 286 amino acid residues and displays sequence homology and activity properties that resemble known laminarases. SCLam is active against barley beta-glucan, laminarin, and lichenan (72, 33, and 10 U mg(-1), respectively). The optimal reaction conditions were identified as 40 °C and pH 6.5. The low-resolution structure was determined using the small-angle X-ray scattering technique, revealing that SCLam is a monomer in solution with a radius of gyration equal to 19.6 Å. To the best of our knowledge, SCLam is the first nonspecific (1,3/1,3:1,4)-β-D-glucan endohydrolase (EC 3.2.1.6) recovered by metagenomic approach to be characterized.