Physiological, biochemical and transcriptional responses of Passiflora edulis Sims f. edulis under progressive drought stress

Abstract

Water deficit stress is responsible for at least 40 % of crop losses worldwide, positioning itself as a strong threat to food security. Purple passion fruit (Passiflora edulis Sims f. edulis) is one of the most desirable exotic fruits on the world market mainly for its organoleptic properties. Information on the response to water deficit stress for purple passion fruit is scarce and in some cases contradictory. Therefore, the objective of the present work was to evaluate the morphological, physiological, biochemical and transcriptional response of purple passion fruit during water deficit and depict its strategy. The response of purple passion fruit plants to two water deficit treatments (T1: 50 % of irrigation, T2: 0% of irrigation compared to control) was evaluated during 40 days of stress, measuring changes in physiological variables related to growth and water relations, as well as the content of metabolites related to stress and the expression of genes associated with drought stress. Results show that the plant prevents water loss, by stomata closure, modulation of growth and accumulation of proline and sugars, while promoting root growth, features associated with tolerance to water deficit. At the expression level, early transcriptional activation of PeDREB2A and PeRD21A were detected in plants under the most severe stress, while PeGOLS1 and PeAFL1 upregulation were observed in plants under milder stress. These results suggest that purple passion fruit plants display an isohydric behavior and evade water deficit stress as a response strategy, where loss of water is avoided.