Rootstock affects the blend of biogenic volatile organic compounds emitted by 'Hass' avocado

Grafting, using tolerant rootstocks, has been necessary to increase avocado (Persea americana Mill.) production in drought, salinity, pest, and soil disease conditions. The avocado rootstock has shown an influence on scion vigor, nutrient absorption, fruit quality, and disease tolerance. Nevertheless, the avocado rootstock influence on the biogenic volatile organic compounds (BVOCs) emitted from 'Hass' shoots has not been reported. Our objective was to study the effect of two avocado rootstocks of the Mexican race on BVOC emitted by avocado 'Hass' shoots. We collected BVOCs emitted by 'Hass' avocado shoots grafted on 'Mexicola' and 'Zutano' rootstocks. All volatile collections were made from living plants for 24 h through a dynamic headspace technique. The chemical profiles were analyzed by gas chromatography coupled to a mass spectrometry (GC-MS). BVOC emission rates were highly variable in amount and composition. The monoterpene alpha-pinene was emitted at 5.06 +/- 0.74, 0.73 +/- 0.14, and 1.43 +/- 0.61 mu g mL(-1) by graft 'Hass'/'Mexicola', 'Hass'/'Zutano' and ungrafted 'Mexicola', respectively. Grafted 'Hass' on 'Mexicola' emitted a wide variety of monoterpenes as beta-pinene, cumene, 3-carene, R-limonene and (Z)-beta-ocimene, whereas grafted plants on 'Zutano' only released alpha-pinene and cumene. Estragole was only detected on ungrafted 'Mexicola'. We found that the chemical profile of volatile compounds released by 'Hass' grafted avocado plants was qualitatively and quantitatively influenced by rootstocks.