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

PRODUCTION AND MORPHO-CYTOLOGICAL CHARACTERIZATION OF BC₂ PROGENIES FROM 5X X 4X AND 4X X 5X CROSSES IN SOLANUM

PARISI M., IOVENE M., FRUSCIANTE L.

Department of Agronomy and Plant Genetics, University of Naples, Via Università 100, 80055 Portici, Italy

fruscian@unina.it

Solanum commersonii, S. tuberosum, aneuploidy, fertility, tuber yield

A breeding scheme involving the production of F₁ triploid and BC₁ pentaploid interspecific bridges has been followed to introgress useful genes from the sexually isolated 1EBN Solanum commersonii (cmm) into S. tuberosum (tbr) gene pool. Here we report on the transmission of extra genome chromosomes from two pentaploid cmm-tbr hybrids (MCPH1 and MCPH3) used in reciprocal crosses with three tetraploid tbr varieties and on the morphology and fertility traits of a sample of six 5x - 4x progenies obtained. The extent of extra genome chromosome transmission has been indirectly assessed by counting the chromosome number of hybrids from four 5x x 4x and two 4x x 5x progenies. Progeny means for chromosome number ranged from 50±0.5 to 54±0.7. On average, chromosome number was higher when the 5x parent used was MCPH3, suggesting a genotype effect on the transmission of extra chromosomes to the hybrid progenies. Despite their aneuploidy, when grown in the field most of BC₂ hybrids closely resembled tbr in terms of morphological traits such as plant vigour, eye depth, stolon length. They were also used both as male and female parents in crosses with tbr. 5x x 4x progenies were fertile when crossed with tetraploid varieties both as male and female parents, whereas 4x x 5x hybrids were generally male sterile, suggesting a negative interaction between tbr cytoplasm and cmm nuclear genes. BC₂ hybrids also showed eterotic effects for tuber yield and introgression of some cmm interesting traits. Out of 16 hybrids screened for tuber yield, five had a significantly higher yield than the tbr control, and 44% of them displayed a high specific gravity of tubers, probably inherited from cmm. Fifty-one % of hybrids analyzed revealed a stomata index similar to that of cmm. Since this parameter has been reported as positively correlated to cold resistance, it could be useful as first rapid selection index of resistant genotypes. Superior hybrids have been selected as parents to produce the BC₃ generation.