NaCl accumulation, shoot biomass, antioxidant capacity, and gene expression of Passiflora edulis f. flavicarpa Deg. in response to irrigation waters of moderate to high salinity

Authors: Ferreira, Jorge; Liu, Xuan; SUDDARTH, STELLA - Driscolls; NGUYEN, CRISTINA - University Of California, Riverside; Sandhu, Devinder

Submitted to: Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/1/2022
Publication Date: 11/5/2022
Citation: Ferreira, J.F., Liu, X., Suddarth, S., Nguyen, C., Sandhu, D. 2022. NaCl accumulation, shoot biomass, antioxidant capacity, and gene expression of Passiflora edulis f. flavicarpa Deg. in response to irrigation waters of moderate to high salinity. Agriculture. 12(11). Article 1856. https://doi.org/10.3390/agriculture12111856.
DOI: https://doi.org/10.3390/agriculture12111856

Interpretive Summary: The yellow passion fruit is a high-value tropical crop with increasing interest in California, Florida, Hawaii, and Puerto Rico and suitable for both the fruit and nutraceutical markets. However, it has not been evaluated for salinity tolerance in the hot semiarid climate of Southern California. We evaluated the effects of irrigation-water salinity on leaf salt accumulation, leaf biomass, antioxidant capacity, and genetic responses of yellow passion fruit vines. The study also evaluated the effect of leaf age and drying methods on leaf antioxidant capacity. Plants were grown in outdoor lysimeter tanks for three years with waters of three different salinity levels, set at 3.0, 6.0, and 12.0 dS m-1. Both sodium and chloride significantly increased with salinity; leaf biomass at 3.0 and 6.0 dS m-1 were similar but reduced in approximately 50% at 12.0 dS m-1. Salinity had no effect on leaf antioxidant capacity but new leaves had the highest leaf antioxidant capacity compared to older leaves; Leaves dried in a low-temperature oven had the same antioxidant capacity and leaves dried by lyophilization (freeze-drying). The analyses of 12 transporter genes, six involved in sodium transport and six in chloride transport, had higher expression in roots than leaves indicating the critical role of roots in ion transport and on the control of leaf-salt concentration. The yellow passion fruit was moderately tolerant to salinity and is a potential new fruit crop for California. The high antioxidant capacity of its leaves make it also suitable for use as an alternative forage for sheep and goats.

Technical Abstract: Passiflora edulis f. flavicarpa (yellow passion fruit) is a high-value tropical crop explored for both fruit and nutraceutical markets. As the fruit production in the US rises, the crop must be investigated for the effects of salinity under semi-arid climates. We accessed the effects of irrigation-water salinity, leaf age and drying method on leaf antioxidant capacity (LAC) and plant genetic responses. Plants were grown in outdoor lysimeter tanks for three years, with waters of electrical conductivities of 3.0, 6.0, and 12.0 dS m-1. Both Na and C1 significantly increased with salinity; leaf biomass at 3.0 and 6.0 ds m-1 were similar but reduced significantly at 12.0 ds m-1. Salinity had no effect on LAC, but new leaves had the highest LAC compared to older leaves. Low-temperature oven-dried (LTO) and freeze-dried (FD) leaves had the same LAC. The analyses of twelve transporter genes, six involved in Na+ transport and six in C1- transport, showed higher expressions in roots than in leaves, indicating a critical role of roots in ion transport and the control of leaf salt concentration Passion fruit's moderate tolerance to salinity and its high leaf antioxidant capacity make it a poential new fruit corop for California, as well as a rich source of flavonoids for the nutraceutical market. Low-temperature oven drying is a potential alternative to lyophilization in preparation for Oxygen Radical Absorbance Capacity (ORAC) analysis of passion fruit leaves.