Mediterranean Long Shelf-Life Landraces: An Untapped Genetic Resource for Tomato Improvement

Abstract

The Mediterranean long shelf-life (LSL) tomatoes are a group of landraces with a fruit remaining sound up to 6-12 months after harvest. Most have been selected under semiarid Mediterranean summer conditions with poor irrigation or rain-fed and thus, are drought tolerant. Besides the convergence in the latter traits, local selection criteria have been very variable, leading to a wide variation in fruit morphology and quality traits. The different soil characteristics and agricultural management techniques across the Mediterranean denote also a wide range of plant adaptive traits to different conditions. Despite the notorious traits for fruit quality and environment adaptation, the LSL landraces have been poorly exploited in tomato breeding programs, which rely basically on wild tomato species. In this review, we describe most of the information currently available for Mediterranean LSL landraces in order to highlight the importance of this genetic resource. We focus on the origin and diversity, the main selective traits, and the determinants of the extended fruit shelf-life and the drought tolerance. Altogether, the Mediterranean LSL landraces are a very valuable heritage to be revalued, since constitutes an alternative source to improve fruit quality and shelf-life in tomato, and to breed for more resilient cultivars under the predicted climate change conditions.

ddRAD sequencing-based genotyping for population structure analysis in cultivated tomato provides new insights into the genomic diversity of Mediterranean ‘da serbo’ type long shelf-life germplasm

“…A variety of functions are associated with JAR1 including resistance to biotic stress. Previous studies evidenced a correlation between jasmonate and reduced ethylene emission in 'de Peniar' accessions 68 , suggesting how the LSL fruit phenotype may be also related to non-ethylene mediated ripening regulation as in the non-ripening tomato mutants 10,74,75 .…”

“…In particular, the alc mutation has been found in Spanish LSL 'da serbo' genotypes, which are commonly called 'de penjar' in Catalonia and Valencia and 'de ramellet' in the Balearic Islands 12,67 . In the 'Alcobaça' landrace the alc mutation was associated to a reduction of ethylene production (i.e., 25% less than 'Rutgers' cultivar 65 , and mutations alc-like have been suggested to play the same role in Italian 'da serbo' LSL landraces 10 . Similar results comparing the ethylene emission in 'Ailsa Craig' and four different 'de penjar' accessions, revealed that ethylene emission may be not only related to alc mutation 68 .…”

“…These LSL tomatoes are generally small, mostly round, although a wide range of shapes can be found, with thick cuticle, and different colors, from yellow to red with several shades. The extended shelf-life might have been the primary selection criteria 10 and is associated with high resilience, manifested in the tolerance to different abiotic and biotic stresses, as well as to a high soluble solids content providing excellent organoleptic properties 11 . This syndrome of phenotypic characteristics of the LSL 'da serbo' landraces results in a clear differentiation from the standard fresh consumption tomatoes.…”

Qualitative Aspects of Some Traditional Landraces of the Tomato “Piennolo” (Solanum lycopersicum L.) of the Campania Region, Southern Italy

“…Therefore, the industrial derivatives are characterized by a certain homologation of “taste” and the impoverishment of the traditional link between territory, traditions, and food habits. [ 2 , 3 ]. However, in recent years, we have observed an opposite trend by consumers, who have started to establish a different orientation in their choice of food products, with the aim of recovering the traditional gastronomic heritage of their own territory [ 4 ].…”

“…Therefore, in the Mediterranean area, different varieties of tomato show similar peculiarities, such as the so-called tomato “de penjar” [ 17 ]. “Piennolo” tomato, like other traditional varieties of tomato distributed in the Mediterranean area, belong to the so-called “long storage (LS)” tomatoes that, as described by Conesa et al [ 3 ], do not need postharvest ripening nor cold temperature storage; in addition, they are drought tolerant enough, due to the typical open field cultivation under semi-arid Mediterranean summer conditions, meaning that plants are irrigated only during first stages after transplantation and rely on occasional rain-fed afterwards in contrast with the commercial practice for most tomato cultivars. LS tomatoes were diffused several centuries ago, in many regions of the Mediterranean area, from the Eastern Iberian Peninsula, to the Balearic Islands, in the Southern Italy and Sicily; all these regions were part of the Crown of Aragón from the end of 13th to early 18th centuries [ 18 ].…”