Effect of X-ray irradiation on olive shoot culture evaluated by morphological measurements, nuclear DNA content and SSR and AFLP markers

Key message

This article presents the first investigation of X-ray irradiation treatments of olive shoot culture followed by detailed genetic analysis of induced mutation events. This was achieved by comparing morphological measurements, studies of nuclear DNA content and molecular marker (SSR and AFLP) analysis.

Abstract

Traditional olive cultivars often need minor phenotypic corrections, which can be assessed using mutation breeding. We investigated the effects of X-ray irradiation at 0, 10, 30 and 60 Gy delivered to in vitro grown shoots of the olive variety ‘Canino’. Morphological measurements showed that growth parameters did not decrease at a 10-Gy dose, that rooting ability was diminished at a 30-Gy dose and that shoot growth was inhibited at a 60-Gy dose. Measurements of acclimatized plants showed that nuclear DNA content decreased with irradiation dose from 2.972 to 2.963 and 2.935 pg/2C nucleus of control, for 10 and 30 Gy treated plants, respectively. SSR profiling using 6 microsatellite loci revealed no polymorphism. AFLP analysis generated in total 630 scorable fragments within 13 primer combinations, of which 179 (28.4 %) were polymorphic. Although no major morphological changes were observed at a 10-Gy dose, a high number of absent/novel fragments were detected by AFLP analysis, indicating that mutation events can also be detected for doses at which growth parameters are not affected.