Genetic basis of long shelf life and variability into Penjar tomato

Abstract

Penjar tomato is a varietal type cultivated in northeast Spain that characteristically has a long shelf life, small fruit, and wide morphological variability among cultivars. To determine the genetic basis for the long shelf life in the Penjar varietal type and to describe the genetic background and agromorphologic characteristics of the group, we studied 27 Penjar accessions representative of the entire range of variation in traits related to agronomic behavior, fruit morphology, and sensory quality. We found that the long shelf life of Penjar (mean: 126.8 days) is due to the ripening mutant alcobaça (alc), and the molecular basis of this mutation is the replacement of thymine by adenine in position 317 of the coding sequence of the NAC.NOR gene; thus, alcobaça (alc) is an allele of non-ripening (nor). The amplified fragment length polymorphism (AFLP) study found 18.07% polymorphic loci within the Penjar varietal type, which is higher than usual in landraces. The variation in agronomic and morphologic traits between accessions was also very high; thus, the heterogeneity of the Penjar group probably results from the introduction of the allele alc in distinct landraces. Our results also show that in germplasm containing the alc mutation shelf life is negatively correlated with fruit size (weight, width, length, and number of locules); thus, the predominance of small fruit within the varietal type is probably the result of this trait being dragged along in the selection for long shelf life.

Sugar-and-acid profile of Penjar tomatoes and its evolution during storage

“…In a previous study, we analyzed genetic variability within the Penjar variety (Casals et al, 2012). Characterization of 118 accessions provided by local farmers enabled us to select 21 accessions representing the major part of the genetic variability found in the variety.…”

“…Thus, we sought to describe the evolution of malic, glutamic, and citric acids and of glucose and fructose during the long aging phase. Moreover, because the alc allele in the Penjar tomatoes occurs in a variety of genetic backgrounds (Casals et al, 2012), we also sought to ascertain the reasons for consumers' postharvest preferences of this variety so that this information could be transferred to breeding programs.…”

Is It Still Necessary to Continue to Collect Crop Genetic Resources in the Mediterranean Area? A Case Study in Catalonia

“…Importantly, only 21.7% of these accessions are present as duplicates in the National Inventory, making the long term availability of these seeds uncertain. Furthermore, some landraces are overrepresented in the ex situ collections because breeding programs developed by Polytechnic University of Catalonia Miquel Agustí Foundation have extensively collected seeds of "Ganxet" (388 accessions) (Casañas et al 1997; Casañas et al 1999 and "Santa Pau" beans (48 accessions) (Almirall et al 2010), and of "Penjar" (361 accessions) (Casals et al 2012), "Montserrat" (96 accessions) (Casals et al 2011), and "Pera de Girona" tomatoes (61 accessions) (Casals et al 2010). Given the high costs of ex situ conservation (Li and Pritchard 2009), studies are underway to characterize the genetic variability within these varieties at the agricultural, morphological, organoleptic, chemical, and DNA levels to build core collections of these varieties (i.e., a limited set (5-20% of the total collection) of accessions chosen to represent the genetic spectrum in the whole collection (van Hintum et al 2000)).…”

“…Farmers value landraces from these species for different reasons. Tomato landraces' organoleptic profile is considered superior to that of modern varieties (Casals et al 2011; Sinesio et al 2007, and the "Penjar" landrace is valued in Catalonia for its long shelf life (Casals et al 2012). Common beans have historically been appreciated for their nutritive properties and for their ability to be stored, and they are key ingredients in many traditional Catalan dishes.…”

“…Agricultural activity has been historically important in this region, covering at present 36% of the surface area. Catalonia is rich in CGR, with many references to landraces found in cookbooks and agricultural books, and some of these landraces are economically important (e.g., "Calçot de Valls" (Allium cepa L.) (Simó et al 2012), "Penjar" tomato (Solanum lycopersicum L.) (Casals et al 2012), or "Ganxet" bean (Phaseolus vulgaris L.) (Casañas et al 1999) study. In Catalonia, nonprofit organizations have carried out several initiatives at the local level to collect and conserve CGR.…”