Proceedings of the XLVII Italian Society of Agricultural Genetics - SIGA Annual Congress

Verona, Italy - 24/27 September, 2003

ISBN 88-900622-4-X

Poster Abstract - 2.53

NEGATIVE ASSISTED SELECTION OF HYBRIDS BETWEEN SOLANUM TUBEROSUM AND ITS INCONGRUENT WILD RELATIVE S. COMMERSONII

M. IOVENE, A. BARONE, S. ALBERINO, A. NUNZIATA, L. FRUSCIANTE, D. CARPUTO

Dept. of Soil, Plant and Environmental Sciences - University of Naples “Federico II”, Via Università 100, 80055 Portici, Italy

AFLP, aneuploidy, resistance to low temperature, resistance to Erwinia carotovora

A breeding scheme based on odd ploidy production was developed to introduce useful genes from the wild Solanum commersonii (cmm) into S. tuberosum (tbr) genome. Hybrids from 5x x 4x crosses were characterized for traits of interest and selection was assisted by AFLP analysis. As expected, most of the hybrids were aneuploids, with a trend towards a low aneuploid grade. More than 75% of the hybrids resembled tbr phenotype for all the morphological traits considered (plant habit, corolla shape, eye depth) but for stolon length. Screening for resistant traits deriving from cmm was also carried out. As for freezing resistance in non-acclimated condition, hybrids were similar to the cultivated susceptible parent. By contrast, killing temperatures of cold acclimated genotypes were distributed between the wild and cultivated parental values, and ranged from –6.1°C to –2.6°C. Interestingly, some hybrids displayed an acclimation capacity higher than 3°C. A wide variability was also found for tuber soft rot resistance, and hybrids with high levels of resistance were identified. In spite of the fact that aneuploidy has often been associated to reduction of male and female fertility, most of hybrids were fertile after crosses with tbr, making it possible to produce a viable offspring. No significant correlation were found between aneuplody and fertility/resistance parameters.

Negative selection was assisted by AFLP cmm-specific markers, in order to identify hybrids combining noteworthy traits with a low wild genome content. Previously selected cmm-specific AFLPs were used to monitor the degree of wild genome content still present in each hybrid. The percentage of cmm-specific markers ranged from 65% to 95%, with an average value of 78%. To select hybrids with a desirable combination of traits, an evaluation index (E.I) was estimated for each genotype considering the following traits: stolon length, eye depth, specific gravity of tubers, resistance to tuber soft rot, resistance to frost (in non-acclimated and acclimated condition). Hybrids with a higher E.I. and a lower wild genome content than average for both traits were selected for further breeding efforts.