BUSCADOR RECOLECTA

Enzymatic flesh browning (EB) is one of the major problems affecting the quality and limiting the shelf life of minimally processed fruit. Traditionally, EB has been measured objectively using colourimeters. However, colourimeters are not suitable for phenotyping large quantities of fruit samples as they measure just one small area of a sample at a time, which hampers the acquisition of representative measurements and renders them time-consuming and costly. Previous research has shown that image analysis of digital photographs could be a viable alternative to obtain colour information of the entire surface of samples for large scale phenotyping, but to date there are no references for its practical application. The aim of this work was to assess the diversity in EB in a large set of cultivars phenotyped using digital photographs and a high-throughput analytical system based on image analysis developed by our team. A set of 143 cultivars from 104 genotypes, including modern references (16 cultivars) and traditional Spanish cultivars from UPNA (67 cultivars) and CITA (60 cultivars) germplasm collections was analysed in 2020 and 2021. The traditional cultivars were part of the core collection, which optimizes the representativeness of the genetic variation of apples preserved in Spanish collections. EB was evaluated in 10 fruits per cultivar and photographed at regular intervals from just after cutting to one hour later. A wide range of EB intensities was observed, with up to 20-fold differences between cultivars, which could be classified into five levels using two indices. The time at which EB was evaluated (30 or 60 min after slicing) had little influence on the classification. Traditional cultivars with low or very low EB were found to be comparable to those of references with less EB. The results show the potential of traditional germplasm to diversify the varietal offer and introduce new traits in apple breeding., This research has been funded by INIA project RTA2015-00052-C02-00 and project
PID2019-108081RR-C22 (APPLECUT) funded by MCIN/ AEI /10.13039/501100011033.

Apple cider-making has a long tradition in many northern Spanish regions, such
as Gipuzkoa in the Basque Country. The production in this region is largely based on
traditional local cider cultivars for which very little information is available on their
pollination requirements, resulting in a generalized low productivity of the orchards.
In this work the self-(in)compatibility, S-alleles and pollen quality have been studied
for the main cider varieties grown in Gipuzkoa, which represent a wide genetic
diversity. The S-RNase genotype of 25 cultivars is firstly reported here, which allows
allocating the cultivars in their corresponding incompatibility group. All the S-alleles
have been previously described, being S26, S3 and S5 the most frequently found.
Regarding pollen quality triploid cultivars, as expected, showed lower viability (<70%)
and germination rates (<20%). Whereas most diploid cultivars showed good pollen
viability (>80%) and germination (>30%) rates, it is noteworthy the low performance
of ‘Urtebete’, very similar to that of triploids. Self-compatibility tests both in vitro and
in situ showed low rates of fruit set and, together with an upper position of the stigmas
related to stamens, reveal a low degree of self-compatibility for most cultivars.
Surprisingly, two cultivars called ‘Moko’ and ‘Txalaka’, showed certain selfcompatibility with around 7% fruit set. All in all, the results will enable to improve
traditional varieties orchard design as well as the profitability of apple cider farms in
the region., This work was financially supported by Diputación Foral de Gipuzkoa/Gipuzkoako
Foru Aldundiaren (contract nº 2019907195) and by PID2019-108081RR-C22 funded by
MCIN/AEI/10.13039/501100011033.