Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

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    Construction of chromosomal recombination maps of three genomes of lilies (Lilium) based on GISH analysis.
    Nadeem Khan, M. ; Shujun Zhou, ; Barba Gonzalez, R. ; Ramanna, M.S. ; Visser, R.G.F. ; Tuyl, J.M. van - \ 2009
    Genome 52 (2009)3. - ISSN 0831-2796 - p. 238 - 251.
    in-situ hybridization - genetic-linkage maps - nuclear-dna amounts - x asiatic hybrids - translocation breakpoints - intergenomic recombination - homoeologous recombination - sexual polyploidization - interspecific hybrids - arabidopsis-thaliana
    Chromosomal recombination maps were constructed for three genomes of lily (Lilium) using GISH analyses. For this purpose, the backcross (BC) progenies of two diploid (2n = 2x = 24) interspecific hybrids of lily, viz. Longiflorum × Asiatic (LA) and Oriental × Asiatic (OA), were used. Mostly the BC progenies of LA hybrids consisted of both triploid (2n = 3x = 36) and diploid (2n = 2x = 24) with some aneuploid genotypes and those of OA hybrids consisted of triploid (2n = 3x = 36) and some aneuploid genotypes. In all cases, it was possible to identify the homoeologous recombinant chromosomes as well as accurately count the number of crossover points, which are called ¿recombination sites¿. Recombination sites were estimated in the BC progeny of 71 LA and 41 OA genotypes. In the case of BC progenies of LA hybrids, 248 recombination sites were cytologically localized on 12 different chromosomes of each genome (i.e., L and A). Similarly, 116 recombinant sites were localized on the 12 chromosomes each from the BC progenies of OA hybrids (O and A genomes). Cytological maps were constructed on the basis of the percentages of distances (micrometres) of the recombination sites from the centromeres. Since an Asiatic parent was involved in both hybrids, viz. LA and OA, two maps were constructed for the A genome that were indicated as Asiatic (L) and Asiatic (O). The other two maps were Longiflorum (A) and Oriental (A). Remarkably, the recombination sites were highly unevenly distributed among the different chromosomes of all four maps. Because the recombination sites can be unequivocally identified through GISH, they serve as reliable landmarks and pave the way for assigning molecular markers or desirable genes to chromosomes of Lilium and also monitor introgression of alien segments
    Interspecific hybridization in lily (Lilium): Interploidy crosses involving interspecific F1 hybrids and their progenies
    Shujun Zhou, ; Barba Gonzalez, R. ; Lim, K.B. ; Ramanna, M.S. ; Tuyl, J.M. van - \ 2008
    In: Floriculture, ornamental and plant biotechnology: advances and topical issues Vol 5 Global Science Books (Floriculture, ornamental and plant biotechnology: advances and topical issues 5) - ISBN 9784903313122 - p. 152 - 156.
    Despite a long history of cultivation, a large number of lily (Lilium) cultivars were still diploid (2n=2x=24) till recently. But polyploid cultivars are rapidly increasing. In addition to having robust stems, large flowers, thicker and larger leaves, polyploids can also serve to combine desirable characters from species of different taxonomic sections; not only from the cultivated groups, viz., Sinomartagon, Archelirion and Leucolirion, but also from sections that include non-cultivated species. Because the F1 hybrids between the species of different taxonomic sections are highly sterile, it is imperative that breeding has to be carried out at the polyploidy level. This chapter is based on our results on using intersectional interspecific hybrids of Longiflorum x Asiatic (LA) and Oriental x Asiatic (OA) groups of lilies and their polyploid backcross progenies BC1, BC2 and BC3). In order to cross genotypes of different ploidy levels, i.e., interploidy crosses, a knowledge of embryo and endosperm ploidy levels is valuable because, unlike in most other plant species, lily has very large chromosomes and the embryo sac formation is of tetrasporic 8-nucleate type. In order to highlight the differences, a comparison is made with the most commonly occurring, monosporic 8-nucleate type of diploid potato, with 24 chromosomes (same as lily). Some of the limitations and constraints associated with interploidy crossing are considered
    Interspecific hybridization in lily: the use of 2n-gametes in interspecific lily hybrids
    Barba Gonzalez, R. ; Lim, K.B. ; Shujun Zhou, ; Ramanna, M.S. ; Tuyl, J.M. van - \ 2008
    In: Floriculture, ornamental and plant biotechnology: advances and topical issues Vol 5 Global Science Books (Floriculture, ornamental and plant biotechnology: advances and topical issues 5) - ISBN 9784903313122 - p. 146 - 151.
    Lily comprises more than 80 species belonging to 7 sections. Within the sections cultivars bred from Sinomartagon, Archelirion, and Leucolirion are the most important in the commercial market. At this moment, the most promising breakthrough in lily breeding is the raising of new cultivar through interspecific hybridization with introgression of useful genetic traits from species or breeding materials belonging to the wild species which are not commonly used so far for commercial breeding. We have been crossing almost all different cross combinations and have succeeded in more than 28 cross combinations since 1980. The F1 hybrids between the species have shown the intermediate phenotypic characteristics. Making interspecific or intergeneric hybrid is laborious but finding the clues, affecting to the most successful embryo formation, and growth is even more difficult and time consuming. Therefore research on the successful interspecific hybridization between distantly related species was carried out at several laboratories in the world. For the successful interspecific hybridization breeding, not only production of F1 interspecific hybrids but also successful production of subsequent generations using interspecific hybrids to introgress valuable trait(s) is important. One of the promising crosses is of course between Orientals and several species such as L. henryi, Asiatics, and trumpet lilies. In this context, we demonstrate the possible methods and some valuable instances of the interspecific hybridization in lilies
    Genome composition of triploid lily cultivars derived from sexual polyploidization of Longiflorum x Asiatic hybrids (Lilium)
    Shujun Zhou, ; Ramanna, M.S. ; Visser, R.G.F. ; Tuyl, J.M. van - \ 2008
    Euphytica 160 (2008)2. - ISSN 0014-2336 - p. 207 - 215.
    in-situ hybridization - interspecific hybrids - aegilops-squarrosa - alstroemeria - gish - recombination - introgression - restitution - mechanisms - progenies
    About 19 cultivars, which had originated from backcrosses between F1 LA (Longiflorum × Asiatic) hybrids (2n = 2x = 24) as female parents and Asiatic cultivars as male parents (2n = 2x = 24), were analyzed with genomic in situ hybridization. 17 of them were triploid (2n = 3x = 36), and two aneuploid (2n = 3x + 1 = 37). The triploid cultivars had resulted from the functional 2n eggs produced by the female parents (F1 hybrids) because first division restitution (FDR) occurred in their meiosis during megasporogenesis. Similarly, the aneuploid cultivars had originated from viable 2n + 1 eggs. The extra chromosome in cultivar 041555 or 041572 resulted from one univalent or one half-bivalent which might have lagged behind when the sister chromatids of the other univalents and half-bivalents were segregating during the FDR process in their LA hybrid parents, respectively. That the majority of cultivars possessed recombinant chromosomes showed that intergenomic recombination might play an important role during the selection of the cultivars directly from BC1 progenies. That five cultivars of the 15 recombinant cultivars only had reciprocal recombinant chromosomes and 10 cultivars had non-reciprocal recombinant chromosomes indicates that the latter are more important. Because 9 of the 10 non-reciprocal recombinant cultivars possessed substitutions for recombinant segments, it also indicated that such substitutions could be an important source for the genetic variation in the sexual triploid BC1 progenies. In such cases there was a potential for the expression of the recessive genes of the backcross parent in a nulliplex (aaa) condition in the substituted segments. Genetic variation resulting from such nulliplex loci might have played a role in the selection of some of the cultivars.
    Interspecific hybridization in Lily (Lilium): Taxonomic and commercial aspects of using species hybrids in breeding
    Lim, K.B. ; Barba Gonzalez, R. ; Shujun Zhou, ; Ramanna, M.S. ; Tuyl, J.M. van - \ 2007
    In: Floriculture, ornamental and plant biotechnology: advances and topical issues Vol 5 Global Science Books (Floriculture, ornamental and plant biotechnology: advances and topical issues 5) - ISBN 9784903313122 - p. 138 - 145.
    With the main goal of generating new groups of lilies, that combine agronomic characteristics of major importance, a large number of crosses were performed among the three most important groups of lilies (Lilium), viz., Asiatic, Longiflorum and Oriental; and to some species, to produce F1 inter-specific hybrids. These hybrids, as well as many other F1 hybrids, were sterile and two approaches were used to overcome sterility: i) chromosome doubling through chemicals and ii) the use of naturally occurring or induced unreduced (2n) gametes. The first approach produced many fertile hybrids, however, due to autosyndetic pairing in the allotetraploids, recombination was not detected through DNA in situ hybridization techniques (GISH), and introgression was not achieved. On the other hand, through extensive meiotic analyses and pollen germination tests, we selected hybrids that were able to produce 2n gametes, and in some cases, hybrids in which 2n gametes could be induced. Many plants were obtained in reciprocal backcrosses and recombination as well as introgression was detected through GISH and FISH analyses. In this chapter we present the success in breeding lilies from different taxonomical sections through the use of naturally occurring and induced 2n gametes. The mechanisms of 2n gamete formation are described and the genetic considerations of their use to achieve introgression and to generate variability are examined.
    Intergenomic recombination and introgression breeding in Longiflorum x Asiatic lilies
    Shujun Zhou, - \ 2007
    Wageningen University. Promotor(en): Richard Visser, co-promotor(en): Jaap van Tuyl. - [S.l.] : S.n. - ISBN 9789085046370 - 110
    lilium - introgressie - plantenveredeling - recombinatie - sporogenie - soortkruising - genomen - kruisen - kruisingen - lilium - introgression - plant breeding - recombination - sporogony - interspecific hybridization - genomes - crossing - crosses
    Lily, one of the economically most important ornamental crops, belongs to the genus Lilium of the family Liliaceae. There are about 80 species in Lilium which are categorized into seven sections, i.e., Lilium, Martagon, Pseudolirium, Archelirion, Sinomartagon, Leucolirion and Oxypetala. Usually, it is not so difficult to cross between the species within each section and the hybrids are fertile. However, it is very difficult to cross the species belonging to different sections. With cut style pollination followed by embryo rescue techniques, such distant interspecific crosses can be possible, but the hybrids are highly sterile. All modern lily cultivars have originated from hybridization among wild lily species. The three main lily cultivar groups, viz., Longiflorum, Asiatic and Oriental, originated from hybridization within one section, i.e., Leucolirion, Sinomartagon and Archelirion respectively. Up to now, about 150 Longiflorum, 4000 Asiatic cultivars, and 2000 Oriental cultivars have been registered. The genomes of Longiflorum (Leucolirion), Asiatic (Sinomartagon) and Oriental (Archelirion) are represented as L (Longiflorum), A (Asiatic) and O (Oriental) genome respectively. They possess quite different valuable traits, and one of the main goals of modern lily breedingareto combine the three distinctive groups in new cultivars. 

    In this thesis, crosses among diploid Asiatic and Longiflorum cultivars, diploid F1 LA hybrids, triploid BC1 cultivars, allotetraploidand allopentaploid lilies were made. 11 diploid F1 LA hybrids and 19 triploids BC1 cultivars which were supplied by the Dutch lily breeding companies, and 23 new BC1, five BC2 and seven BC3 progenies were analyzed with conventional cytological methods, flow cytometry and genomic in situ hybridization.

    The configurations of metaphase I during meioses of the F1 LA hybrids are quantitatively variable, ranging from no bivalent to 12 bivalents in different pollen mother cells. This implies that LA hybrids have abnormal meiosis and normal meiosis, and indicates that LA hybrids have possibilities to produce aneuploid gametes, 2n gametes and n gametes (Chapter 2). Because the bivalents disjoin and the univalents divide simultaneously at anaphase I of the observed pollen mother cells, it is concluded that F1 LA hybrids have more potential to produce IMR 2n gametes than FDR 2n gametes I (Chapter 2). However, most of the BC1 progenies result from FDR 2n gametes and less from IMR 2n gametes. Probably, FDR 2n gametes have better viability than IMR 2n gametes because of chromosome and gene imbalance in the latter (Chapters 3 & 4).

    Besides the mode of 2n gamete formation, some crossover events, e.g., single, threestranddouble, four strand double, four strand triple crossover, etc, are clearly elucidated based on the GISH results from anaphase I of F1 LA hybrids (Chapter 2). The intergenomic recombinant chromosomes of triploid BC1 progenies mainly originate from single crossover (Chapters 3 & 4). The intergenomic recombinant chromosomes caused by other crossover events are confirmed in diploid BC1 progenies (Chapter 4).

    Based on GISH analysis of 19 BC1 cultivars from the Dutch lily breeding companies, 17 of the BC1 cultivars are eutriploid and two hypertriploid (Chapter 3). Nevertheless, among 45 new BC1 progenies, 10 of them are diploid, while the others are triploid (Chapter 4). This is the first reported finding that LA hybrid can produce functional haploid gametes. This finding might be valuable for lily introgression breeding.

    Only limited BC2 progenies, which originated from crosses between triploid BC1 cultivars and diploid Asiatic cultivars, were analyzed with GISH. They were predominantly diploid and they contained very few Longiflorum chromosomes or segments (Chapter 5).

    Allopentaploid lilies have relatively good male fertility as determined from their pollen germination. They were successfully crossed with Asiatic cultivars and Longiflorum cultivars. Most of the BC3 progenies were pseudoeuploids that possessed euploid chromosome numbers (2n=3x=36) but the parental genomes were aneuploid as a result of chromosome substitutions. Apart from this, one aneuploid (2n=3x+1=37) was also present. Both the pseudoeuploids and the aneuploids might contribute to genetic variation and are potentially useful for selection.   

    Based on the results of lily interploid crosses (2x-3x, 2x-4x, 2x-5x and their reciprocals), diploid, triploid, tetraploid, and pentaploid lilies could be used as male parents when they had some degree of male fertility. Most diploid and triploid lilies could be used as female parents regardless of their male fertility. On the contrary, allotetraploid and allopentaploid lilies could hardly be used as female parents even though they had good fertility as estimated from pollen germination tests. The success and failure of interploid crosses in lilies depends on the viability of the gametes and the ploidy level of the secondary nucleus. From the process of tetrasporic eight-nucleate embryo sac formation in Lilium , it is derived that diploid, triploid, tetraploid, and pentaploid lilies produce tetraploid, hexaploid, octaploid and decaploid secondary nuclei in their embryo sacs respectively. Thus, It is suggested that tetraploid secondary nucleus might be ideal for lily endosperm development; hexaploid secondary nucleus are acceptable; but octaploid or higher secondary nuclei are not ideal (Chapter 5).

    The difference between 2x-4x and 4x-2x or 2x-5x and 5x-2x is obvious, because one was successful and the other not. A clear difference was also observed between 2x-3x and 3x-2x and between AA x LA and LA x AA. The difference is possibly caused by the frequency of functional gametes, ploidy level of endosperm and the interaction between embryo development and endosperm development (Chapter 5).

    2n gametes and n gametes might play different roles in lily breeding. The former is more useful for polyploid breeding; the latter may be valuable for introgression breeding. We could not over- or underestimate either of them, because the LA hybrids which could produce functional 2n gametes or n gametes are very limited. Especially, it is more difficult to find LA hybrids which produce functional n gametes. The advantages of 2n gametes over mitotic doubling in lily breeding have been well confirmed (Chapters 3 and 4). One of the further tasks is how to use the LA hybrids which produce viable n gametes in lily breeding.
    Meiotic polyploidization with homoeologous recombination induced by caffeine treatment in interspecific lily hybrids
    Lim, K.B. ; Barba Gonzalez, R. ; Shujun Zhou, ; Ramanna, M.S. ; Tuyl, J.M. van - \ 2005
    Korean Journal of Genetics 27 (2005)3. - ISSN 0254-5934 - p. 219 - 226.
    lilium hybrids - bc2 progenies - restitution - cytokinesis - gish
    Caffeine solution was injected into the flower bud to recover F, fertility of the intersectional diploid Lilium species hybrid (2n=2x=24). 0.3% of caffeine solution was the most effective concentration to produce fertile 2n-gametes. The male and female gametes had a range of fertility following caffeine injection in relation to the different sizes of flower buds. The gametes from the treated OA-hybrids showed to be fertile. They were crossed both as male and female parents to the Asiatics, and produced 279 BC, progeny plants. Flowcytometric and chromosomal observation confirmed that all progenies were triploid (2n=3x=36), indicating that the 2n-gametes from the OA-hybrid were functional following caffeine treatment. There was no homoeologous recombination between parental species in the progeny derived from male gametes of the OA-hybrid. However, three plants originating from the female gametes showed homoeologous recombination between Oriental and Asiatic genomes. The functional female gametes were produced when treated at the range of 20-23mm and 34-37mm of flower bud length. Based on the chromosome constitution of the triploid BC1 progenies, it was concluded that FDR 2n-gamete was functional and homoeologous recombination had occurred during the origin of 2n gametes.
    Characterisation of distant Alstroemeria hybrids: application of highly repetitive DNA sequences from A. ligtu spp. ligtu
    Shujun Zhou, ; Jeu, M.J. de; Visser, R.G.F. ; Kuipers, A.G.J. - \ 2003
    Annals of Applied Biology 142 (2003)3. - ISSN 0003-4746 - p. 277 - 283.
    in-situ hybridization - molecular cytogenetics - interspecific hybrids - physical organization - ovule culture - sequences - heterochromatin - localization - family - aurea
    Clones from a Sau3A family of eight highly repetitive sequences previously isolated from a genomic DNA library of Alstroemeria ligtu ssp. ligtu were sequenced and found to be highly conserved. A trinucleotide microsatellite repeat [GCA](3-4) was present. A second, unrelated, Sau3A repeat was also characterised. Southern analysis proved that the isolated repeats were specific for the A. ligtu subspecies and could not be detected in other Chilean or Brazilean Alstroemeria species. As shown by in situ hybridisation, the Sau3A family and the unrelated Sau3A repeat co-localised at distinct sites along most chromosomes of Alstroemeria ligtu ssp. ligtu and Alstroemeria ligtu ssp. simsii. The present set of species-specific repetitive sequences enables the identification of A. ligtu chromosomes, and thus the tracking of chromosome transmission to interspecific hybrids and their progeny.
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