Homoeologous Chromosome Pairing and Alien Introgression in Backcrossing Progenies Derived from Hybrids Solanum tuberosum (+) Mexican 2x (1 EBN) B-Genome Potato Species (original) (raw)
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Genome, 1999
Four somatic hybrids derived from a diploid wild species Solanum etuberosum and a diploid tuber-bearing Solanum clone 463-4, together with five BC1 and three BC2 plants, were analyzed by genomic in situ hybridization (GISH). None of the four somatic hybrids had the expected chromosome constitutions, i.e., 24 chromosomes from each fusion parent. Either one chromosome from S. etuberosum or one from the potato parent 463-4 was lost in the hybrids. Three BC1 plants had exactly one set of S. etuberosum chromosomes. The other two BC1 plants either had one extra or one fewer S. etuberosum chromosome, possibly because their somatic hybrid parents had an extra or had lost one S. etuberosum chromosome. The presence of one set, or close to one set, of S. etuberosum chromosomes in all BC1 plants suggests a preferential pairing and segregation of the S. etuberosum chromosomes in the somatic hybrids. Two of the three BC2 plants had 52 chromosomes, deviating significantly from the expected chromos...
Heredity, 1995
Backcross progenies, BC1 and BC2, derived from crossing a hexaploid potato (+) tomato fusion hybrid to tetraploid potato, were monitored for the presence of alien tomato chromosomes. For discriminating the tomato chromosomes from those of potato, both mitotic and meiotic chromosome preparations were labelled differentially through total genomic DNA in situ hybridization (GISH). The presence or absence of individual tomato chromosomes in the BC progeny was identified through RFLP analyses using chromosome-specific DNA probes. The results indicated that the BC 1 plant possessed only nine chromosomes of tomato instead of the expected haploid set of 12. Of the nine persistent tomato chromosomes, there were three pairs that formed bivalents and three singles that formed univalents at meiosis. One of the single chromosomes was strikingly longer as a result of some structural mutation and could easily be identified in the hexaploid parent, the BC1 and in some of the BC2 plants. From the analyses of BC2 progeny there were indications of the presence in the BC1 of tomato chromosomes 1, 3 and 6 in duplicate, and chromosomes 8, 9 and 10 in the haploid condition. The number of tomato chromosomes transmitted to BC2 plants varied from one to six. The results of GISH revealed that a few BC2 plants possessed more tomato chromosomes than those deduced from RFLP analysis. This indicated the presence of some tomato chromosomes in duplicate and others in the haploid condition. The potential value of these genotypes for establishing potato lines with additions and substitutions of tomato chromosomes is discussed.
Genome, 2016
A major bottleneck to introgressive hybridization is the lack of genome collinearity between the donor (alien) genome and the recipient crop genome. Structural differences between the homeologs may create unbalanced segregation of chromosomes or cause linkage drag. To assess large-scale collinearity between potato and two of its wild relatives (Solanum commersonii and Solanum chacoense), we used BAC-FISH mapping of sequences with known positions on the RH potato map. BAC probes could successfully be hybridized to the S. commersonii and S. chachoense pachytene chromosomes, confirming their correspondence with linkage groups in RH potato. Our study shows that the order of BAC signals is conserved. Distances between BAC signals were quantified and compared; some differences found suggest either small-scale rearrangements or reduction/amplification of repeats. We conclude that S. commersonii and S. chacoense are collinear with cultivated Solanum tuberosum on the whole chromosome scale, ...
Genome, 2008
Thirty-six percent of the wild potato ( Solanum L. section Petota Dumort.) species are polyploid, and about half of the polyploids are tetraploid species (2n = 4x = 48). Determination of the type of polyploidy and development of the genome concept for members of section Petota traditionally has been based on the analysis of chromosome pairing in species and their hybrids and, most recently, DNA sequence phylogenetics. Based on these data, the genome designation AABB was proposed for Mexican tetraploid species of series Longipedicellata Buk. We investigated this hypothesis with genomic in situ hybridization (GISH) for both representatives of the series, S. stoloniferum Schltdl. and S. hjertingii Hawkes. GISH analysis supports an AABB genome constitution for these species, with S. verrucosum Schltdl. (or its progenitor) supported as the A genome donor and another North or Central American diploid species (S. cardiophyllum Lindl., S. ehrenbergii (Bitter) Rydb., or S. jamesii Torrey) as...
Euphytica
Wild potato relatives are rich sources of desirable traits for introgressive hybridisation into cultivated potato. One of them, Solanum commersonii (2n = 2x = 24, 1EBN, endosperm balance number), is an important species belonging to the potato tertiary genepool. It can be used in potato breeding through bridge crosses and 2n gamete production. Triploid F1 hybrids between S. commersonii (through spontaneous 2n egg formation) and diploid 2EBN Solanum tuberosum Group Phureja were crossed with S. tuberosum Group Tuberosum, resulting in successive backcross 1, 2 and 3 progenies. The main aim of this study was to determine if there are any barriers to homoeologous pairing and recombination in the allotriploid (S. commersonii × potato) hybrids and their backcrosses, and so to predict if S. commersonii chromosomes can be transmitted to the next generation and introgressed into their recipient potato chromosomes. Microscopic observations of spread pollen mother cells suggested no preferentia...
Agronomy, 2022
Wild relatives of cultivated potato are used in breeding to increase the genetic diversity of Solanum tuberosum (AAAA genome) varieties. Wild Mexican allotetraploid species Solanum stoloniferum (AABB genome) was used in breeding for extreme resistance to viruses and late blight. In this study, genomic in situ hybridization (GISH) was used for visualization of introgression of genetic material of the B subgenome of S. stoloniferum into the genome of backcross hybrids. The fertile hexaploid hybrid had 48 chromosomes of the A genome and 24 chromosomes of the B subgenome. Plants of the BC1 generation were pentaploid having the AAAAB genome constitution and three selected BC2 hybrids were aneuploid, containing one to six chromosomes of the B subgenome and 48 chromosomes of the A genome. The B subgenome of S. stoloniferum was inherited in the backcross generations as single chromosomes and in rare cases as recombinant chromosomes. GISH showed that chromosome pairing in the backcross hybri...
Introgressive Hybridization in Potato Revealed by Novel Cytogenetic and Genomic Technologies
American Journal of Potato Research
Potato is the third most important food crop in the world and is crucial to ensure food security. However, increasing biotic and abiotic stresses jeopardize its stable production. Fortunately, breeders count on a rich pool of wild relatives that provide sources for disease resistance and tolerance to environmental stresses. To use such traits effectively, breeders require tools that facilitate exploration and exploitation of the genetic diversity of potato wild relatives. Introgression programs to incorporate such alien chromatin into the crop have so far relied on cytogenetic and genetic studies to tap desired traits from these wild resources. The available genetic and cytogenetic tools, supplemented with more recent genomic technologies, can assist in the use of potato relatives in pre-breeding. This information can also facilitate cisgenesis and genome editing to improve potato cultivars. Despite the abundant and rapidly growing genomic information of potato, that of its wild relatives is still limited. Resumen La papa es el tercer alimento más importante en el mundo y es crucial para garantizar la seguridad alimentaria. No obstante, el aumento de los factores adversos bióticos y abióticos pone en riesgo la estabilidad de la producción. Afortunadamente, los mejoradores cuentan con rico acervo de parientes silvestres que suministran fuentes de resistencia a enfermedades y tolerancia a factores ambientales adversos. Para utilizar tales caracteres efectivamente, los mejoradores requieren de herramientas que faciliten la exploración y explotación de la diversidad genética de los parientes silvestres de la papa. Los programas de introgresión para incorporar tal cromatina ajena al cultivo hasta ahora han recurrido a estudios citogenéticos y genéticos para captar caracteres deseables de esas fuentes silvestres. Las herramientas genéticas y citogenéticas disponibles, suplementadas con tecnologías genómicas más recientes, pueden asistir en el uso de los parientes de la papa en pre-mejoramiento. Esta información también puede facilitar la cisgénesis y la edición genómica para mejorar las variedades de papa. A pesar del abundante y rápido crecimiento de la información genómica de la papa, la de los parientes silvestres es aún limitada.
Genome, 2012
Wild potato ( Solanum L. sect. Petota Dumort.) species contain diploids (2n = 2x = 24) to hexaploids (2n = 6x = 72). J.G. Hawkes classified all hexaploid Mexican species in series Demissa Bukasov and, according to a classic five-genome hypothesis of M. Matsubayashi in 1991, all members of series Demissa are allopolyploids. We investigated the genome composition of members of Hawkes’s series Demissa with genomic in situ hybridization (GISH), using labeled DNA of their putative progenitors having diploid AA, BB, or PP genome species or with DNA of tetraploid species having AABB or AAAaAa genomes. GISH analyses support S. hougasii Correll as an allopolyploid with one AA component genome and another BB component genome. Our results also indicate that the third genome of S. hougasii is more closely related to P or a P genome-related species. Solanum demissum Lindl., in contrast, has all three chromosome sets related to the basic A genome, similar to the GISH results of polyploid species ...
Genomic Outcomes of Haploid Induction Crosses in Potato (Solanum tuberosum L.)
The challenges of breeding autotetraploid potato (Solanum tuberosum) have motivated the development of alternative breeding strategies. A common approach is to obtain uniparental dihaploids from a tetraploid of interest through pollination with S. tuberosum Andigenum Group (formerly S. phureja) cultivars. The mechanism underlying haploid formation of these crosses is unclear, and questions regarding the frequency of paternal DNA transmission remain. Previous reports described aneuploid and euploid progeny, which, in some cases, displayed genetic markers from the haploid inducer. Here, we surveyed a population of 167 presumed dihaploids for large-scale structural variation that would underlie chromosomal addition from the haploid inducer, and for small-scale introgression of genetic markers. In 19 progeny, we detected ten of the twelve possible trisomies and, in all cases, demonstrated the non-inducer parent origin of the additional chromosome. Deep sequencing indicated that occasion...
Plant Breeding, 1999
Intraspeci_c somatic hybrids have been produced by protoplast fusion in eight combinations involving 09 dihaploids "1n 1x 13# in an attempt to provide new material for potato breeding[ Cytological analy! sis revealed extensive variation in chromosome number\ such as aneu! ploid\ aneusomatic and mixoploid hybrids[ Most of the hybrids represented the expected chromosome number of 37^however\ the frequency of aneuploids reached 49) in some combinations[ Some hybrids carried structurally rearranged chromosomes and exhibited a high frequency of aberrant anaphases[ Isozyme and random ampli_ed polymorphic DNA "RAPD# patterns of the hybrids from the same fusion combination were uniform[ In the _eld\ somatic hybrids showed wide phenotypic variation in 19 morphological characters[ There was a signi_cant correlation between certain leaf characters and the ploidy level\ which may be used to distinguish the tetraploid hybrids from hexaploids and octoploids[ Tuber yield and~owering intensity were highest in tetraploid hybrids "1n 3x 37#[ Eighteen of the 62 hybrids reached higher yields than the standard variety {Adretta|[ Floral devel! opment and fertility were restored in hybrids derived from fusions between non!~owering or sterile dihaploids[