Potato germ plasm enhancement with disomic tetraploid Solanum acaule. II. Assessment of breeding value of tetraploid F1 hybrids between tetrasomic tetraploid S. tuberosum and S. acaule

Abstract

The breeding value of tetraploid F1 hybrids between tetrasomic tetraploid S. tuberosum and the disomic tetraploid wild species S. acaule was examined. The F1 hybrids showed a tuber yield and appearance comparable to those of their cultivated parent, indicating a potential as acceptable breeding stocks despite the 50% contribution to their pedigree from wild S. acaule. The cytological behavior of the tetraploid F1 hybrids was examined to determine the probability of recombination for the introgression of S. acaule genes. The majority of the meiotic configurations at metaphase I was bivalents and univalents with mean frequencies of 17.6 and 9.9, respectively. Further, a low frequency of trivalents and quadrivalents was observed. An acceptable low level of meiotic irregularities were observed at the later stages of microsporogenesis, and a reasonable level of pollen stainability was obtained. Therefore, these hybrids could likely be employed for further introgression. From the cytological observations, the following speculations were drawn: (1) some genomic differentiation exists between the S. acaule genomes, (2) at least one of the S. acaule genomes may be homoeologous to the S. tuberosum genomes, (3) intergenomic recombination would likely occur due to the nature of the genomic constitution of the hybrids, and (4) the nature of sesquiploidy of the hybrids may facilitate efficient introgression and establishment of unique aneuploid and euploid recombinant genetic stocks.

Diversity of potato genetic resources

“…In some cases, a trait of interest may not be present in the 2x (2EBN) and 2x (1EBN) gene pools; however, a broad range of genetic diversity present in wild potato species could be used for breeding purposes. There are several reports of the successful use of this strategy ( Iwanaga et al 1991 , Watanabe et al 1994 , 1995 ). Using these effective tools, potato breeders can gain access to the promising characteristics present in wild potato species.…”

Potato germplasm enhancement for resistance to biotic stresses at CIP. Conventional and biotechnology-assisted approaches using a wide range of Solanum species

“…brevidens (Watanabe et al ., 1995) . The method may have additional value, namely to exploit additional genes derived from the rescue pollinator such as IvP 35 (Hermsen & Verdenius, 1973 ;Iwanaga et al ., 1991 ;Watanabe et al ., 1992aWatanabe et al ., , 1994aWatanabe et al ., , 1995 by enhancing intergenomic translocation (Clulow et al ., 1993 ;Valkonen et al, 1994c) between the tuber-bearing and non tuber-bearing species in sexual hybrids.…”

“…Introgression of filial generations from distant interspecific crosses often induces aneuploids (Ross, 1986 ;Watanabe, 1994a;Watanabe et al ., 1994a) . Identification of such aneuploids can be conducted by regular light microscopy using simple chromosome staining, but the work is very cumbersome unless the operator is sufficiently skilled.…”

Phenotypic characterization and nuclear microsatellite analysis reveal genomic changes and rearrangements underlying androgenesis in tetraploid potatoes (Solanum tuberosum L.)

“…There were no differences in growth, color, number and size of leaflets and color and size of floral corollas and anthers between anther-derived (di)haploids or tetraploids and their tetraploid anther donor S. acaule. This may be because S. acaule is largely self-pollinating (Watanabe et al 1994), which results in a high degree of homozygosity and thus a low level of variation in its (di)haploid population. In the present study, we obtained androgenic (di)haploids of tetraploid S. tuberosum, which not only flower but also are male fertile.…”