B-Glucans are major hemicelluloses in shoot shells of the woody bamboo Guadua chacoensis

FERNÁNDEZ, PAULA VIRGINIA; CAPARRÓS FRENTZEL, MARÍA EVELINA; CIANCIA, MARINA

San Martín

Simposio; 3º Simposio Argentino de Glicobiología; 2019

CONICET - UNSAM - FIL

Woody bamboos are perennial plants with very high rates ofgrowth. Bamboo shoots are the new culms, valorized by theirnutritional properties. Bamboo shoot shells are thick leaves thatprotect the growing structures. They comprise up to 60% of theshoot weight, so they represent an important byproduct fromshoot processing.Guadua Kunth (Poaceae) is a genus native from the Americancontinent that has not been studied in detail. Sequentialextraction (hot water, Na2CO3 and KOH solutions) was carried out on the alcohol insoluble residue obtained from shoot shells ofG. chacoensis. As expected for grasses, major yields were observed in alkaline, hemicellulosic extracts (1M and 4M KOH),which represented together 47% w/w of the cell wall material.Usually, glucuronoarabinoxylans -GAX- are the majorhemicellulosic polymers, however, in this case, β-glucans showed to be the predominant polysaccharides. The four majoralkaline extracts (1MA, 1MB, 4MA and 4MB) were furtherseparated into a minor water soluble fraction and a major water insoluble fraction. Water soluble fractions probed to be rich in GAX, and they also contained significant amounts of mixedlinkage glucans (ratio 4Glc:3Glc from 1:0.05 to 1:0.31). On theother hand, insoluble fractions comprised mostly xyloglucans(XG). On this basis, XG is the major hemicellulose in this specialized structure, although being a polysaccharide commonly reported as a minor component in Type-II cell walls.