Abstract:
Avocado consumption is increasing year by year, and its cultivation has spread to many
countries with low water availability, which threatens the sustainability and profitability of avocado
orchards. However, to date, there is not much information on the behavior of commercial avocado
rootstocks against drought. The aim of this research was to evaluate the physiological and molecular
responses of ‘Dusa’ avocado rootstock to different levels of water stress. Plants were deficit irrigated
until soil water content reached 50% (mild-WS) and 25% (severe-WS) of field capacity. Leaf water
potential (Ψw), net CO2 assimilation rates (AN), transpiration rate (E), stomatal conductance (gs), and
plant transpiration rates significantly decreased under both WS treatments, reaching significantly
lower values in severe-WS plants. After rewatering, mild- and severe-WS plants showed a fast
recovery in most physiological parameters measured. To analyze root response to different levels
of drought stress, a cDNA avocado stress microarray was carried out. Plants showed a wide
transcriptome response linked to the higher degree of water stress, and functional enrichment of
differentially expressed genes (DEGs) revealed abundance of common sequences associated with
water stress, as well as specific categories for mild-WS and severe-WS. DEGs previously linked to
drought tolerance showed overexpression under both water stress levels, i.e., several transcription
factors, genes related to abscisic acid (ABA) response, redox homeostasis, osmoprotection, and
cell-wall organization. Taken altogether, physiological and molecular data highlight the good
performance of ‘Dusa’ rootstock under low-water-availability conditions, although further water
stress experiments must be carried out under field conditions.
