Effect of edaphoclimate on the resin glycoside profile of the ruderal Ipomoea parasitica (Convolvulaceae).

Abstract

The latex of Ipomoea (Convolvulaceae) is a source of a special kind of acylsugars called resin glycosides, which are highly appreciated because of their biological activities (i.e. laxative, antimicrobial, cytotoxic etc.). Most research has been conducted in perennials with tuberous roots, where resin glycosides are stored. However, their content and variation are unknown in annual vines that lack this type of root, such as in the case of Ipomoea parasitica. This species contains research/biological and human value through its fast growth, survival in harsh environments, and employment in humans for mental/cognitive improvements. These qualities make I. parasitica an ideal system to profile resin glycosides and their variations in response to edaphoclimate. Topsoil samples (0-30 cm depth) and latex from petioles of I. parasitica were collected in two localities of central Mexico. The latex was analyzed through UHPLC-ESI-QTOF, and soil physico-chemical characteristics, the rainfall, minimum, average, and maximum temperatures were recorded. We also measured canopy (%), rockiness (%), and plant cover (%). A Principal Component Analysis was conducted to find associations between edaphoclimate and the resin glycosides. Forty-four resin glycosides were found in the latex of I. parasitica. Ten correlated significantly with three components (47.07%) and contained tetrasaccharide, pentasaccharide, and dimers of tetrasaccharide units. Five resin glycosides were considered constitutive because they were in all the plants. However, exclusive molecules to each locality were also present, which we hypothesize is in response to significant microhabitat conditions found in this study (temperature, clay content, pH, and potassium). Our results showed the presence of resin glycosides in I. parasitica latex and are the basis for experimentally testing the effect of the conditions above on these molecules. However, ecological, molecular, and biochemical factors should be considered in experiments designed to produce these complex molecules.