Search Results

You are looking at 1 - 10 of 27 items for :

  • "polyembryony" x
  • Refine by Access: All x
Clear All
Free access

Y. Aron, S. Gazit, H. Czosnek, and C. Degani

The segregation pattern of individuals originating from selfing of several monoembryonic cultivars and one polyembryonic line indicated that polyembryony in mango was of genetic nature. All the plants originating from monoembryonic cultivars bore monoembryonic fruits. A one-monoembryonic to three-polyembryonic segregation pattern was observed among individuals originated from the polyembryonic line, indicating that polyembryony in mango is under the control of a single dominant gene.

Free access

J.A. López-Valenzuela, O. Martínez, and O. Paredes-López

Fifteen mango cultivars were examined using randomly amplified polymorphic DNA (RAPD) markers with decamer primers of arbitrary sequence. Thirteen of the 40 primers screened were informative and 109 amplified DNA bands were selected as RAPD markers. Specific RAPD markers for some mango cultivars were identified. Cluster analysis based on the 109 RAPD markers produced a dendrogram of the genetic relatedness of the 15 mango cultivars. `Manila' and `Carabao' were the most similar, which is in good agreement with their putative pedigrees. The four major bifurcations in the dendrogram separated correctly the genotypes into four groups according to their geographic origin. Bulk segregant analysis of polyembryonic and monoembryonic cultivars detected a specific RAPD marker for polyembryony. These markers may facilitate the management of mango germplasm for breeding purposes.

Free access

Raymond J. Schnell and Robert J. Knight Jr.

Five isozyme systems were used to detect zygotic seedlings from five polyembryonic cultivars of mango (Manifera indica L.). Significant differences were found between cultivars (x2 = 35.53, P < 0.001) for the percentage of zygotic and nucellar seedlings detected. The range of variation in the percentage of off-types was from 0% in 13-1 to 64% in Golek. The percentage in Sabre was 4%, and 24% and 36% in Tupentine and Madoe, respectively. Three of eight rootstock mother trees of Turpentine were determined to be off-types.

Free access

I. Oiyama and S. Kobayashi

Some undeveloped seeds from mature Citrus fruit of monoembryonic diploid cultivars crossed with a tetraploid selection were observed to be polyembryonic. The multiple embryos formed a small mass the the micropylar end. Plants regenerated in vitro from the embryos in polyembryonic seeds were triploid and showed identical peroxidase banding patterns on acrylamide gels. These results indicate that the multiple embryos found in the undeveloped seed from monoembryonic diploid × tetraploid crosses are genetically identical and of zygotic origin.

Free access

Kim D. Bowman, Frederick G. Gmitter Jr., and Xulan Hu

We examined the relationship between seed size and shape in Citrus and the number and type of seedlings produced by individual seeds for each of three citrus cultivars. Seed size and shape were related to the number of seedlings produced and the likelihood of recovering a zygotic seedling. The relationship between seed size and shape and the likelihood of recovering a zygotic seedling most often was connected with weight and thickness of a seed. This relationship might be of sufficient strength to use in some aspects of cultivar development. However, the relationship did not appear strong enough to be of practical value for application in commercial production of purely nucellar rootstock seedlings.

Full access

Tyler Hoskins and Ryan N. Contreras

as a single seed in each cell, showing ( A ) one or two seedlings and ( B ) one or three seedlings, demonstrating the presence of polyembryony. Apomixis was first reported in Sarcococca ruscifolia ( Orr, 1923 ), and a number of studies listed in the

Open access

Alan T. Whittemore and Zheng-Lian Xia

distinguish, suggests that the actual frequency with which two embryos are formed may be even higher. This strongly supports the conclusion of Shattuck (1905) and Walker (1950) that elms show a high frequency of simple polyembryony, in which multiple

Free access

Víctor Galán Saúco, María José Grajal Martín, Domingo Fernández Galván, Águeda Coello Torres, José Juárez, and Luis Navarro

A putative polyploid seedling tree appeared among the polyembryonic mango (Mangifera indica L.) `Gomera-1', widely used as a rootstock in the Canary Islands. Initially detected because of its wider and more coriaceous leaves, further studies showed that fruit from this seedling are considerably larger than normal, although all other fruit characteristics (including polyembryony) were similar to those of standard `Gomera-1' (G-1) fruit. The progeny of this plant has, to date, proved to be morphologically identical to the mother plant. Studies of seedlings from normal G-1 trees growing in the same orchard showed that 10% of the plants had morphological characteristics similar to those of the putative polyploid seedling. Flow cytometry and chromosome count analyses confirmed that G-1 is diploid, whereas the putative polyploid is a stable tetraploid. The study also showed that the morphologically abnormal seedlings from diploid parent trees were spontaneous tetraploids.

Free access

Marìa Andrade-Rodrìguez, Angel Villegas-Monter, and M. Alejandra Gutièrrez-Espinosa

Polyembryony is an important characteristic for citrus that allows them to be propagated clonally through seed. Even when it is genetically controlled by a quantitative trait, the environment in which the seed is developed can affect it. The aims of this investigation were to evaluate polyembriony in two citric rootstocks in two harvest cycles and embryo germination of polyembrionic seeds. Embryos of 300 seeds of Citrus volkameriana and C. amblycarpa were counted and measured in Summer-Fall and Winter 1998 and 1999, respectively; embryo of 50 seeds of both rootstocks were germinated in vitro. The number of embryos per seed was 1.9 and 1.6 in C. volkameriana and 4.7 and 5.7 in C. amblycarpa. In C. volkameriana, we observed 42% of monoembryonic seeds during summer-fall and 67% in winter, whereas in C. amblycarpa 5.0 and 4.1% were detected, respectively. Only embryos that were larger than 1 mm long germinated. Even when germination takes similar time (5 to 6 days), further growth is faster in larger embryos (5 to 10 mm) than smaller ones. Therefore, size of embryos would need to be considered for propagation purposes.

Free access

Gloria A. Moore

We have produced a number of transgenic citrus plants via Agrobacterium-mediated transformation of seedling stem segments with a vector plasmid containing a β-glucuronidase (GUS) gene. All regenerated green shoots produced in our experiments are assayed histochemically for expression of GUS by cutting a section from the base of the shoot. Many of the shoots express GUS only in sectors, which vary in size from shoot to shoot. Analyses suggest that sectored regenerated shoots are chimeric, consisting of nontransformed cells as well as transformed cells. However, plants derived from shoots with large GUS+ sectors in the original assays do not necessarily contain the GUS gene; conversely, some plants derived from shoots with small sectors appear solidly transformed. Plants that appear solidly transformed have maintained gene expression for up to 5 years. None of the transgenic plants have obviously altered morphologies. It has not been possible to analyze progeny plants because of the long juvenile periods and polyembryony of the primary transformants. However, because citrus is clonally propagated, long-term phenotypic stability of primary transformants is the most important factor in producing useful transgenic plants.