Use of mutant platforms to discover novel postharvest fruit-quality traits in Cucurbita pepo

Mutant platforms represent a great technological advantage for increasing genetic variability in vegetable crops, thereby improving the identification and selection of new allelic variants and traits for vegetable breeding programs.
At the University of Almeria, we have generated a Cucurbita pepo EMS mutant collection composed of about 3,800 M₂ families.
To explore the genetic variability of this platform, we are developing massive plant-phenotyping protocols for different traits, including, among others: sex expression, fruit and seed set and development, accumulation of bioactive compounds and resistance to plant pathogens.
In this paper we present two screening approaches for the identification of mutants, both of which could improve the postharvest fruit quality of zucchini.
Since postharvest chilling injury (PCI) in this species is known to be associated with an induced biosynthesis of both ethylene and oxidative stress metabolites, the mutant collection was screened for both ethylene insensitivity and tolerance to oxidative stress.
By using the triple-response assay in etiolated seedlings, we developed a massive screening that allowed the detection of four ethylene-insensitive mutant families.
Ethylene-insensitive mutants were found to be affected in sexual expression, fruit set and parthenocarpy, and are also expected to be tolerant to postharvest chilling injury (PCI). A massive phenotyping method has been also developed in order to select oxidative-stress-tolerant mutants.
The method was first developed in 10 commercial cultivars by germinating seeds in the presence of hydrogen peroxide (H₂O₂) and the catalase inhibitor aminotriazole (AT). Given that the developed protocol distinguished varieties based on their response to oxidative stress, it has been used to screen the C. pepo mutant collection.
The identified cultivars and mutants that are more tolerant to oxidative stress during germination and as seedlings are also expected to be more tolerant to abiotic stresses, including PCI tolerance during fruit storage.

VIII International Postharvest Symposium: Enhancing Supply Chain and Consumer Benefits – Ethical and Technological Issues

A. García, S. Manzano, Z. Megías, E. Aguado, C. Martínez, D. Garrido, M.M. Rebolloso, J.L. Valenzuela, M. Jamilena

phenomics, massive screenings, chilling injury, ethylene, oxidative stress

https://doi.org/10.17660/ActaHortic.2018.1194.53