Phenotypic and genetic diversity of Spanish tomato landraces

- Common characteristics were identified in populations of the same landrace.
- Overlap of the spectrum of variation of different landraces was found.
- Promising sources of variation for different traits were identified.
- The sustainable cultivation of these materials might require some level of selection.
- High within landrace diversity found justifies extensive collections for conservation.

The structure of Spanish landraces of tomato (Solanum lycopersicum L.) has been analyzed. This diversity has been evaluated using agro-morphological characteristics (43 descriptors), quality parameters (solid soluble contents and individual sugars and organic acids) and DNA markers (amplified fragment length polymorphisms, AFLP). A wide range of variation was found for all traits but in the DNA marker level. Certain common characteristics could be identified in populations of the same landrace in several of the dimensions analyzed, but generally, an overlap of the spectrum of variation of different landraces was found. The results indicate that in each landrace the populations are strongly selected using very basic morphological characteristics such as fruit shape, colour or ribbing, while other traits vary depending on each farmer preferences. Seed mixing and pollen contamination might introduce variation which would be purged by farmers at the morphological level, but would be maintained in quality and yield traits. Despite the introduction of spurious variation it would be still possible to identify certain relations between quality attributes and the morphological traits defining specific landraces. The existence of a wide level of variation in plant yield and quality profiles enables the development of selection programmes targeted to provide farmers with materials with economically viable yield and excellent organoleptic quality. The results also highlight the necessity to stress the efforts in morpho-agronomical and quality characterization over molecular characterization in the ex situ management of these resources, as well as not to underestimate the importance of intra-varietal variability.