Frequency and Characteristics of Nucellar and Zygotic Seedlings in Three Cultivars of Trifoliate Orange

Khan, Iarar A.; Roose, Mikeal L.

doi:10.21273/jashs.113.1.105

Cited by 28 publications

(1 citation statement)

References 7 publications

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“…first markers used to characterize varieties (Tatum et al, 1974) and to study the phylogenesis of citrus (Scora, 1988). Isozymes were used routinely to identify the zygotic or nucellar origin of seedlings (Soost et al, 1980;Khan and Roose, 1988; . .…”

Section: Biochemical and Molecular Variabilitymentioning

confidence: 99%

Genetic Diversity of Cultivated Tropical Plants

Hamon¹,

Séguin²,

Perrier³

et al. 2003

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These relationships probably vary as a function of the population structure. They are generally strong if there is a serious gametic disequilibrium. To proceed from this reflection, however, we must tackle specific questions: Are the different types of molecular markers equivalent? Are strong structures at the molecular scale, which control the gametic disequilibrium generalized on the genome as a whole, systematically associated with strong structures for agronomic characters? Do the structures at these two levels therefore coincide?Several methods have been proposed to construct the core collections. As a general rule, they are based on a stratification of the base collection and then on a random sample within each group thus defined, according to various modalities. When data are available for morphoagronomic evaluation, it is useful to consider the structure of the genetic diversity established with the help of genetic markers in order to maximize the agronomic diversity and minimize the loss of alleles that are rare overall but occasionally significant.The constitution of a core collection must therefore be founded on an excellent description of the populations and on a sound understanding of their structure. Statistical tools are indispensable here. For each type of marker, it is important to use a measure of difference between the relevant taxonomic units (individuals or populations) from the perspective of their mathematical properties and their interpretation in genetic terms. In the same way, the choice of algorithms of representation of dissimilarities must be based on an equilibrium between maximum efficiency and minimum complexity, irl order to deal with large tables covering more than 100 individuals. By comparing the structures observed with the help of various types of descriptors, we can envisage overall the organization of a plant's genetic diversity. This question can be tackled in various ways, among others, by looking for structures common to two or several trees. In these conditions, how can we construct consensus trees or common minimum trees? What is their reliability and their biological significance?This work provides the elements of an answer to these questions, beginning with the study of eleven types of plants, chosen .so as to cover a wide range of biological characteristics (perennial, annual, autogamous, allogamous, etc.): asian rice, banana, cacao, cassava, citrus, coconut, coffee, pearl millet, rubber tree, sorghum, and sugarcane. Three methodological chapters complement these studies. The first is devoted to the use of biological and molecular markers to analyse the diversity of collections, the second addresses data analysis, and the third describes a method for constituting core collections based on maximization of variability.

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Section: Biochemical and Molecular Variabilitymentioning

confidence: 99%

Genetic Diversity of Cultivated Tropical Plants

Hamon¹,

Séguin²,

Perrier³

et al. 2003

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Citrus

Ollitrault¹,

Navarro²

2011

Fruit Breeding

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Citrus is the most extensively produced tree fruit crop in the world. There are two clearly differentiated markets: the fresh fruit and the processed juice market. Citrus species are essentially diploids (2n = 2x = 18) and were domesticated in Southeast Asia several thousand years ago and then spread throughout the world. Most of the cultivated citrus species are part of the Citrus genus containing, depending on the taxonomist, between 16 and 156 species. The relative complexity of these classifications results from the conjunction of a broad morphological diversity, total sexual interspecific compatibility within the genus and apomixis. There are four basic taxa on the basis of morphological descriptors and molecular data (C. maxima (Burm.) Merr., the pummelos; C. medica L., the citrons, C. reticulata Blanco, the andarins, and C. micrantha Wester). The other cultivated species (C. aurantium L., the sour orange; C. sinensis (L.) Osbeck, the sweet orange; C. paradisi Macf, the grapefruit; C. limon (L.) Burm. f., the lemon, and C. aurantifolia (Christm.) Swingle, the lime) appeared by recombination among the basic taxa. Most of the citrus scion cultivars result from the selection of spontaneous bud mutations identified in production orchards. Today several projects of ploidy manipulation are developed in different countries to select seedless triploid mandarins. Fruit quality (size, color, easy-peeling), seedlessness, and the extension of the harvest season are the main selection objectives for fresh market cultivars. The majority of the rootstocks used for propagation are original species or ancient natural hybrids. However, intergeneric hybrids (Citrus × Poncirus) such as citranges, citrumelos, and citrandarins have an increasing importance. The first rootstock breeding objective is adaptation to soil conditions and soil pathogens. The most widespread needs would be tolerance to CTV. Biotechnology is strongly integrated into breeding and propagation schemes. Shoot tip grafting is widely used for sanitation of the mother plants in certification propagation schemes. Somatic hybridization is an effective tool used for scion and rootstock breeding. Functional genomics studies ESTs, microarray platforms, and a full genome sequence are available. Efficient and reliable transformation systems for several economically important citrus species exist. (Résumé d'auteur

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A simple chromosomal marker can reliably distinguishes Poncirus from Citrus species

et al. 2006

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Several chromosome types have been recognized in Citrus and related genera by chromomycin A(3 )(CMA) banding patterns and fluorescent in situ hybridization (FISH). They can be used to characterize cultivars and species or as markers in hybridization and backcrossing experiments. In the present work, characterization of six cultivars of P. trifoliata ("Barnes", "Fawcett", "Flying Dragon", "Pomeroy", "Rubidoux", "USDA") and one P. trifoliata x C. limonia hybrid was performed by sequential analyses of CMA banding and FISH using 5S and 45S rDNA as probes. All six cultivars showed a similar CMA(+) banding pattern with the karyotype formula 4B + 8D + 6F. The capital letters indicate chromosomal types: B, a chromosome with one telomeric and one proximal band; D, with only one telomeric band; F, without bands. In situ hybridization labeling was also similar among cultivars. Three chromosome pairs displayed a closely linked set of 5S and 45S rDNA sites, two of them co-located with the proximal band of the B type chromosomes (B/5S-45S) and the third one co-located with the terminal band of a D pair (D/5S-45S). The B/5S-45S chromosome has never been found in any citrus accessions investigated so far. Therefore, this B chromosome can be used as a marker to recognize the intergeneric Poncirus x Citrus hybrids. The intergeneric hybrid analyzed here displayed the karyotype formula 4B + 8D + 6F, with two chromosome types B/5S-45S and two D/5S-45S. The karyotype formula and the presence of two B/5S-45S chromosomes clearly indicate that the plant investigated is a symmetric hybrid. It also demonstrates the suitability of karyotype analyses to differentiate zygotic embryos or somatic cell fusions involving trifoliate orange germplasm.

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Frequency and Characteristics of Nucellar and Zygotic Seedlings in Three Cultivars of Trifoliate Orange

Cited by 28 publications

References 7 publications

Genetic Diversity of Cultivated Tropical Plants

Genetic Diversity of Cultivated Tropical Plants

Citrus

A simple chromosomal marker can reliably distinguishes Poncirus from Citrus species

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