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

Salsomaggiore Terme, Italy - 26/29 September, 2001

ISBN 88-900622-1-5

Poster Abstract

FERTILITY, FIELD PERFORMANCE AND CYTOPLASMIC COMPOSITION OF POTATO BC₁ PROGENIES DERIVED BY INTERSPECIFIC HYBRIDIZATION WITH SOLANUM COMMERSONII DUN.

SCOTTI N., MONTI L., CARDI T.

CNR-IMOF, Research Institute for Vegetable and Ornamental Plant Breeding, Via Universita’ 133, Portici (Na), Italy

male fertility, cytoplasmic organelles, Solanum

It is well known that a concerted gene expression between the genomes of nucleus, plastids and mitochondria is necessary to achieve a proper cell development and plant performance, but little attention has been given by plant breeders and geneticists to genetic variability in cytoplasmic organelles. This is mainly due to difficulties in enlarging and analyzing genetic variability at the cytoplasmic level by conventional procedures. Backcross progenies were obtained by crossing one Solanum commersonii (+) S. tuberosum somatic hybrid (SH9A) with five S. tuberosum genotypes. They showed variability for male fertility and agronomic performance depending on the S. tuberosum genotype used in backcrosses and on the cross direction, but not for female fertility. BC₁ progenies with LT-7, Tollocan or Carmine cytoplasms segregated for male sterility, whereas reciprocal BC₁s and those with LT-5 or 7XY.1 cytoplasms were usually male fertile. To detect correlations between cytoplasm composition and phenotypic data, we carried out molecular analyses on parental cytoplasms. Analysis of mtDNA and cpDNA revealed a high variability among the tested genotypes. The three S. tuberosum clones LT-7, Tollocan and Carmine revealed the same cp/mtDNA configuration observed in the original S. tuberosum clone used for protoplast fusion. On the other hand, LT-5 and 7XY.1 were rather distant from the other S. tuberosum genotypes. Cluster analysis, based on the presence/absence of species-specific bands detected by molecular analyses, allowed to arrange the genotypes analyzed in two groups for cpDNA and in four groups for mtDNA. These results support the hypothesis that the male sterility observed in S. commersonii (+) S. tuberosum somatic hybrids was due to incompatibilities between a sensitive cytoplasmic genome of S. tuberosum and the nuclear genes of S. commersonii (Cardi et al, 1999). Further, our results suggest that LT-5 and 7XY.1 genotypes do not have the sensitive cytoplasmic genes involved in the induction of male sterility.

Reference

Cardi T., Bastia T., Monti L., Earle E.D. (1999) Organelle DNA and male fertility variation in Solanum spp. and interspecific somatic hybrids. Theor. Appl. Genet. 99: 819-828