title: Structural Modifications of Fructans in Aloe barbadensis Miller (Aloe Vera) Grown under Water Stress.
abstract: Aloe barbadensis Miller (Aloe vera) has a Crassulaceae acid metabolism which grants the plant great tolerance to water restrictions. Carbohydrates such as acemannans and fructans are among the molecules responsible for tolerating water deficit in other plant species. Nevertheless, fructans, which are prebiotic compounds, have not been described nor studied in Aloe vera, whose leaf gel is known to possess beneficial pharmaceutical, nutritional and cosmetic properties. As Aloe vera is frequently cultivated in semi-arid conditions, like those found in northern Chile, we investigated the effect of water deficit on fructan composition and structure. For this, plants were subjected to different irrigation regimes of 100%, 75%, 50% and 25% field capacity (FC). There was a significant increase in the total sugars, soluble sugars and oligo and polyfructans in plants subjected to water deficit, compared to the control condition (100% FC) in both leaf tips and bases. The amounts of fructans were also greater in the bases compared to the leaf tips in all water treatments. Fructans also increase in degree of polymerization with increasing water deficit. Glycosidic linkage analyses by GC-MS, led to the conclusion that there are structural differences between the fructans present in the leaves of control plants with respect to plants irrigated with 50% and 25% FC. Therefore, in non-stressed plants, the inulin, neo-inulin and neo-levan type of fructans predominate, while in the most stressful conditions for the plant, Aloe vera also synthesizes fructans with a more branched structure, the neofructans. To our knowledge, the synthesis and the protective role of neo-fructans under extreme water deficit has not been previously reported.
authors.affiliation: Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Casilla 653, Santiago, Chile.
authors.forename: Carlos
authors.initials: C
authors.lastname: Salinas
authors.affiliation: Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Casilla 653, Santiago, Chile.
authors.forename: Michael
authors.initials: M
authors.lastname: Handford
authors.affiliation: Department of Plant and Microbial Biology, University of California, Berkeley, CA, 94720, United States of America.
authors.forename: Markus
authors.initials: M
authors.lastname: Pauly
authors.affiliation: Department of Biochemistry, University of Cambridge, Cambridge, CB2 1QW, United Kingdom.
authors.forename: Paul
authors.initials: P
authors.lastname: Dupree
authors.affiliation: Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Casilla 653, Santiago, Chile.
authors.forename: Liliana
authors.initials: L
authors.lastname: Cardemil
mesh_terms: D000504:Aloe / Q000737:chemistry* / Q000378:metabolism*; D002241:Carbohydrates / Q000737:chemistry; D005630:Fructans / Q000737:chemistry* / Q000378:metabolism*; D008401:Gas Chromatography-Mass Spectrometry; D015394:Molecular Structure; D010936:Plant Extracts / Q000737:chemistry; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013312:Stress, Physiological; D014867:Water
chemical_list: D002241:Carbohydrates; D005630:Fructans; D010936:Plant Extracts; D014867:Water