scholarly journals Culture of Embryo with a Segment of Ovary Improved Germination and Crossability of Distant Hybrids in Indica Rice

1970 ◽  
Vol 5 (5) ◽  
pp. 46-50
Author(s):  
Bindeshwar Prasad Sah ◽  
Raj Kumar Niroula ◽  
Hari Prasad Bimb
Keyword(s):  
Wild Species ◽  
Indica Rice ◽  
Embryo Rescue ◽  
Continuous Light ◽  
Male Sterile ◽  
Cultivated Rice ◽  
Distant Hybridization ◽  
Hybrid Plants ◽  
Hybrid Embryo

Distant hybridization in the genus Oryza is realized as an efficient Biotechnological tool for plant breeding work to introgress useful gene/s from diverse array of wild relatives into cultivated rice. This study was carried out to improve the germination frequency of hybrid embryo to enhance the crossability between O. sativa sub spp. indica and wild species. Three cultivars of indica rice viz. IR 64, Radha 4 and IR 69618 - CMS A line (cytoplasmic male sterile A line) were pollinated with the pollen of O. latifolia, O. minuta and O. officinalis. Hybrid caryopsis containing embryos were rescued at tenth day of pollination. In vitro germination frequency of rescued embryos were compared by culturing embryo alone and embryo with a bit of ovary during 2005-06 at Biotechnology Unit, Khumaltar, Lalitpur, Nepal. Culture was maintained at 25±1°C under dark until germination and there after continuous light. In majority of the cross combinations, the germination frequencies were found to be higher when embryo excised and cultured with small portion of ovary. This technique yielded up to 100 per cent germination which were later employed to study the crossability between species. Depending upon the cultivars of O. sativa, the frequencies of crossability varied from 0.53 to 3.08 per cent with highest for Radha 4/O. minuta. A total of 38 hybrid plants were successfully produced from 88 cultured embryos isolated from 2644 pollinated florets. Inclusion of a bit of ovary along with embryo in in vitro culture was found to be an effective method not only to improve the germination frequency of hybrid embryo, but also to increase the crossability between cultivars of cultivated rice and their distant relatives. Key words: Embryo rescue; Interspecific hybrid; Oryza sativa; Wild species; O. latifolia; O. minuta; O. officinalis. DOI: 10.3126/sw.v5i5.2655 Scientific World, Vol. 5, No. 5, July 2007 46-50

Organogenesis from cultured floral meristems of a male sterile tobacco hybrid

1981 ◽  
Vol 59 (9) ◽  
pp. 1665-1670 ◽  
Author(s):  
G. S. Hicks ◽  
Robin Browne ◽  
S. A. Sand
Keyword(s):  
Gibberellic Acid ◽  
Basal Medium ◽  
Continuous Light ◽  
Direct Influence ◽  
Male Sterile ◽  
Normal Sequence ◽  
Skoog Medium ◽  
Tobacco Hybrid ◽  
Floral Meristems

Very young floral meristems of a male-sterile tobacco hybrid were excised and cultured on Linsmaier and Skoog medium in continuous light. Basal medium was supplemented with kinetin and gibberellic acid, singly and in combinations. On medium with kinetin, all four types of floral organs arose in the normal sequence and pattern and the male sterile phenotype was expressed, GA3 suppressed the formation of these organs. The data show that male sterile organs may form and begin differentiation in vitro without direct influence from the plant.

Embryo Rescue Culture Medium for Improved Synthesis of 4x Wheat × Rye Hybrids

1994 ◽  
Vol 42 (4) ◽  
pp. 493
Author(s):  
CH Balatero ◽  
NL Darvey
Keyword(s):  
Embryo Rescue ◽  
Favourable Effect ◽  
Embryo Formation ◽  
Step Procedure ◽  
Hybrid Embryo ◽  
One Step ◽  
Well Differentiated ◽  
Semi Solid ◽  
Optimum Recovery

The cross-incompatibility barrier between 4x wheat and rye has limited the genetic base for triticale breeding. Experiments designed to improve the synthesis of wheat-rye amphihaploids were conducted. The effects of 2,4-D on crossability and 3x hybrid embryo differentiation, and the influence of one-step and two-step media on the culture of immature 3x embryos in vitro, were investigated. Application of 10 mg L-1 2,4-D slightly improved seed set but significantly reduced the frequency of normal embryos. In contrast to the reported favourable effect of 2,4-D on haploid embryo formation in wheat × maize crosses, the application of 2,4-D in the present study offers no real advantage on amphihaploid embryo formation from 4x wheat × rye crosses. For small and immature wheat-rye hybrid (3x) embryos, optimum recovery in vitro was obtained via a two-step procedure consisting of a semi-solid MN medium followed by MS medium supplemented with IAA (1 mg L-1) and BAP (1 mg L-1). For bigger and well-differentiated embryos, the use of a one-step Gamborg's B5 medium was sufficient.

A Sorghum bicolor × S. macrospermum hybrid recovered by embryo rescue and culture

2005 ◽  
Vol 53 (6) ◽  
pp. 579 ◽  
Author(s):  
H. James Price ◽  
George L. Hodnett ◽  
Byron L. Burson ◽  
Sally L. Dillon ◽  
William L. Rooney
Keyword(s):  
Nuclear Dna ◽  
Embryo Rescue ◽  
Nuclear Dna Content ◽  
Female Parent ◽  
Male Sterile ◽  
Leaf Pubescence ◽  
Culture Techniques ◽  
Close Phylogenetic Relationship ◽  
Improvement Programs

Although exotic germplasm is extensively used in sorghum improvement programs, Sorghum species classified in sections other than Eu-sorghum have not been utilised as germplasm because of strong reproductive barriers involving pollen–pistil incompatibilities. S. macrospermum is of particular interest to sorghum breeders because of its close phylogenetic relationship and cytogenetic similarities to S. bicolor and its resistance to important sorghum pests and pathogens, such as sorghum midge and sorghum downy mildew. A vegetatively vigorous interspecific hybrid was obtained from a cross between a cytoplasmic male-sterile S. bicolor plant and S. macrospermum by using embryo rescue and in vitro culture techniques. The hybrid was morphologically intermediate to S. bicolor and S. macrospermum in leaf width, leaf pubescence, plant height, inflorescence morphology, chromosome number and nuclear DNA content. It was male-sterile like its ATx623 parent. The hybrid produced no offspring when used as the female parent in a backcross with S. bicolor. This is the first confirmed hybrid between S. bicolor and S. macrospermum, and to our knowledge, it is the first reported hybrid between S. bicolor and any Sorghum species outside the Eu-sorghum section.

Interspecific hybridization of Medicago sativa L. and M. rupestris M. B. using ovule–embryo culture

1985 ◽  
Vol 27 (2) ◽  
pp. 238-245 ◽  
Author(s):  
T. J. McCoy
Keyword(s):  
Medicago Sativa ◽  
Embryo Culture ◽  
Interspecific Hybrid ◽  
Interspecific Hybrids ◽  
Embryo Rescue ◽  
Culture Method ◽  
Hybrid Plants ◽  
Successful Recovery ◽  
Hybrid Embryo ◽  
Medicago Sativa L

An ovule–embryo culture method was used to produce the first interspecific hybrids between alfalfa (Medicago sativa L.) and Medicago rupestris M. B. Culture of fertilized ovules from the cross diploid (2n = 2x = 16) M. sativa (jpjp) × diploid (2n = 2x = 16) M. rupestris began 14 days after pollination. After 5 days in culture, the interspecific hybrid embryo was removed and transferred to fresh medium, where development into a plant occurred. Forty-six M. sativa – M. rupestris F1 hybrids have been recovered using this technique. All but one of the 46 F1 hybrids were diploid (2n = 2x = 16); the only exception was tetraploid (2n = 4x = 32). The most frequent meiotic configurations observed in the F1 hybrid plants were eight bivalents or seven bivalents and two univalents, indicating significant homology between M. sativa and M. rupestris genomes. However, pollen stainability (0–12%) and pollen germination (0–6%) were extremely low. Similar to the production of the F1, no first backcross (BC1) plants were obtained from seed; however, the ovule–embryo culture method was found to be a very effective method for recovering BC1 plants and hundreds of BC1 plants have been produced. The BC1 plants from crossing the F1 with diploid M. sativa were predominantly diploid. Medicago rupestris can now be considered a potential germplasm source for alfalfa improvement. The ovule–embryo culture method represents the first successful recovery of Medicago interspecific hybrids via some form of embryo rescue. Importantly, it appears this technique can be applied to other interspecific hybrid combinations in the Medicago genus.Key words: Medicago, alfalfa, embryo culture, interspecific hybrid.

scholarly journals Plant Hybridization as an Alternative Technique in Plant Breeding Improvement

2019 ◽  
pp. 1-11
Author(s):  
Immaculate Mueni Mwangangi ◽  
Joshua Kiilu Muli ◽  
Johnstone Omukhulu Neondo
Keyword(s):  
Plant Breeding ◽  
Chromosome Doubling ◽  
Embryo Rescue ◽  
Dichlorophenoxyacetic Acid ◽  
Distant Hybridization ◽  
Embryo Abortion ◽  
Sexual Hybridization ◽  
Plant Hybridization ◽  
Whole Plants

For ages, plant breeders have relied on the genetic variability that results from sexually crossing plants within the same species. However, the variability that exists within species populations is inadequate, hence the need to exploit desirable traits of interest in distantly related or even unrelated plants through hybridization techniques. Hybridization can be categorized into two; sexual and somatic. Sexual hybridization, also referred to as wide or distant hybridization involves combining two genomes from different parental taxa through pollination, either naturally or by induction. Somatic hybridization involves the fusion of somatic cells instead of gametes, which highly depends on the ability to obtain viable protoplasts and eventually differentiate them to whole plants in vitro. The impacts of hybrids can either be positive or negative. Among the positive attributes of hybrids that have been exploited is heterosis, which results either from dominance, over-dominance or epistasis. Negative ones include sterility, arrested growth of the pollen tube and embryo abortion. To overcome these problems, chromosome doubling, the use of hormones such as 2, 4-Dichlorophenoxyacetic acid (2, 4-D) and embryo rescue have been employed to overcome sterility, arrested growth of pollen tubes and embryo abortion respectively. After the development of hybrids, different hybrid identification techniques have been used to test them such as the use of molecular and morphological markers, cytogenetic analysis and fluorescent in situ hybridization. The use of hybridization techniques in plant improvement remains a vital tool to cross species barriers and utilization of important attributes in unrelated crop plants which could not have been achieved through conventional techniques of plant breeding.

scholarly journals Introgression of Fragaria Species using a Streamlined Synthetic Octoploid System

HortScience ◽  
1997 ◽  
Vol 32 (3) ◽  
pp. 548D-548
Author(s):  
Robert H. Bors ◽  
J. Alan Sullivan
Keyword(s):  
Cold Hardiness ◽  
Embryo Rescue ◽  
Continuous Light ◽  
Original System ◽  
Fold Increase ◽  
Center Of Diversity ◽  
Synthetic Octoploid ◽  
Strawberry Cultivars ◽  
Fragaria Species

Fragaria species from the center of diversity have not been integrated into octoploid commercial strawberry cultivars because of ploidy level differences. Even though traits such as disease resistance, enhanced flavor, cold hardiness, and vigor are known to exist in the diploid, tetraploid, and hexaploid species, they cannot be easily used for breeding. The synthetic octoploid method circumvented introgression difficulties by combining lower ploidy species and doubling to the octoploid level. Although easily crossed to cultivars, the use of synthetic octoploids has been minimal as it has been extremely difficult to create them. By working to improve bottlenecks of the original system, improved methodology has been developed and 170 synthetic octoploids have been produced. This represents more than a 100-fold increase in efficiency. The following factors played a major role in improving the system: wide germplasm base; use of F. vesca as a common genome; embryo rescue; 5% colchicine applied in vitro by dropper method for 24 hours followed by a quick rinse and continuous light in a 18C growth chamber. F. vesca, F. nilgerrensis, F. nubicola, F. viridis, F. orientalis, and F. moschata have been incorporated into synthetic octoploids in this study.

Cytological analysis of hybrid embryos of intergeneric crosses between Salix viminalis and Populus species

2010 ◽  
Vol 58 (1) ◽  
pp. 42 ◽  
Author(s):  
Agnieszka Bagniewska-Zadworna ◽  
Maria K. Wojciechowicz ◽  
Maciej Zenkteler ◽  
Stanisław Jeżowski ◽  
Elżbieta Zenkteler
Keyword(s):  
Laser Scanning ◽  
Populus Trichocarpa ◽  
Embryo Rescue ◽  
Laser Scanning Microscopy ◽  
Salix Viminalis ◽  
Confocal Laser ◽  
Hybrid Plants ◽  
Populus Species ◽  
Intergeneric Hybridisation

Intergeneric hybridisation between Salix viminalis L. as the female and four Populus species (Populus trichocarpa, P. tremula, P. × canadensis and P. simonii) as male pollen donors was performed by in vitro stigma pollination. To overcome postzygotic barriers, transfer of hybrid embryos to new medium is necessary. We carried out detailed ultrastructural analyses to establish: (i) at which stage of embryo development the first signs of programmed cell death (PCD) could be detected; and (ii) at which stage the lack of serious or irreversible changes guaranteed that advanced development of hybrid plants could occur after embryo rescue. Transmission electron microscopy and confocal laser scanning microscopy revealed the presence of both developing and degenerating embryos. Developing globular, heart-shaped, and early cotyledonary embryos contained cells of correct ultrastructure. The only sign of intergeneric hybridisation was a delay in development for a few days, in comparison with control embryos. The earliest indicators of embryo degeneration were noted at 9 days after pollination (DAP). The most common indicators were excessive embryo vacuolisation, which was characterised by a large number of vesicles and formation of small vacuoles, as well as enlarged central vacuoles. Extended plastid thylakoids, folding of the cell wall, and autophagosomes were observed. Our detailed investigation of PCD in hybrid embryos enabled us to conclude that the embryo rescue technique was most effective in intergeneric willow × poplar crosses if applied between 9 and 16 DAP.

Progress in backcrossing between Carica papaya × Vasconcellea quercifolia intergeneric hybrids and C. papaya

2006 ◽  
Vol 46 (3) ◽  
pp. 419 ◽  
Author(s):  
R. A. Drew ◽  
S. V. Siar ◽  
C. M. O'Brien ◽  
A. G. C. Sajise
Keyword(s):  
Pollen Fertility ◽  
Carica Papaya ◽  
Embryo Rescue ◽  
The Philippines ◽  
Intergeneric Hybrids ◽  
Tropical Fruit ◽  
Hybrid Plants ◽  
Large Numbers ◽  
Backcross Populations

Papaya is a major tropical fruit crop worldwide, however, all genotypes are susceptible to Papaya ringspot virus type P (PRSV-P). Protocols have been developed to produce large numbers of intergeneric hybrids between Carica papaya L. and Vasconcellea quercifolia, which is PRSV-P resistant. Although pollen fertility of these hybrids was low, backcross populations were produced in both Australia and the Philippines when papaya flowers were pollinated with pollen from 11 hybrid plants that had been identified as having some pollen fertility and were PRSV-P resistant. Plantlets were produced after embryo rescue and culture in vitro. Second backcross generations (BC2) were easier to produce than first backcross (BC1) generations as pollen fertility was >80% in male BC1 plants. Variation in time to PRSV-P symptom expression and severity of virus symptoms in the backcross generations was observed in both countries. Commercially acceptable fruit were produced in the BC2 generation. The results demonstrate that efforts in wide hybridisation to transfer PRSV-P resistance to C. papaya, are better directed towards crosses between C. papaya and V. quercifolia than with other Vasconcellea species.

scholarly journals Interploid Hybridization of Cucumis melo and C. metuliferus

1999 ◽  
Author(s):  
Jeff Adelberg ◽  
Halina Skorupska ◽  
Bill Rhodes ◽  
Yigal Cohen ◽  
Rafael Perl-Treves
Keyword(s):  
Wild Species ◽  
Chromosome Doubling ◽  
Fertility Restoration ◽  
Embryo Rescue ◽  
Early Spring ◽  
Late Winter ◽  
Crop Species ◽  
Primary Focus ◽  
First Time

The long-term motivation for this research is to transfer useful traits from a broad based gene pool of wild species into the narrow base of a cultivated crop in Cucumis. Our primary focus was to use polyploid prior to fertilization as a tool to overcome fertility barriers in the cross between C. melo and C. metuliferus. In conducting this research, we explored all combinations of tetraploid and diploid parents, in reciprocal combinations. Pollinations were made in both the field and greenhouse, using emasculated flowers, moneocious females, and open pollination by insect vectors, with morphological selection criteria. After observations of thousands of ovaries, we still have no definitive proof that this hybridization yielded viable embryos. The most promising results came from using tetraploid C. metuliferus, as the maternal parent in the interspecific hybridization, that set fruit were seeds contained small embryos that did not germinate. To obtain fruit set, it was important to rear plants in a cooler sunny greenhouse, as would be found in late winter/early spring. A second interspecific hybrid between wild and cultivated Cucumis, C. hystrix x C. sativus, yielded fertile progeny for the first time, while concomitantly working toward our primary goal. Two distinct treatments were necessary; 1) special plant husbandry was necessary to have the wild species produce fruit in cultivation, and 2) embryo rescue followed by chromosome doubling in vitro was required for fertility restoration. Backcrosses to crop species and resistance to nematodes are compelling areas for further work.

Seed-borne fungi of cowpea [Vigna unguiculata (L.) Walp] and their possible control in vitro using locally available fungicides in Botswana.

2016 ◽  
Vol 5 (11) ◽  
pp. 5016 ◽  
Author(s):  
K. B. Khare* ◽  
Loeto D. ◽  
Wale K. ◽  
Salani M.
Keyword(s):  
Seed Germination ◽  
Continuous Light ◽  
Sodium Hypochlorite Solution ◽  
Distilled Water ◽  
Percentage Germination ◽  
Department Of Agriculture ◽  
Hypochlorite Solution ◽  
Cowpea Cultivars ◽  
Petri Plate

Seeds of three cowpea cultivars namely Black eye, ER 7 and Tswana obtained from the Department of Agriculture Research, Gaborone were tested for the presence of seed-borne fungi, and their possible control in vitro using locally available fungicides. Four hundred fifty seeds of each cultivar of cowpea were disinfected with 2% sodium hypochlorite solution for 10 min and washed three times with sterile distilled water before placing them in PDA plates (5 seeds/9 cm Petri plate), incubated at 22±2o C for 12 hour each under continuous light and dark. A total of eight fungi were detected from seeds of cowpea. These were Aspergillus flavus, A. niger, Cylindrocarpon sp., Fusarium equisiti, F. oxyaporum, Penicillium chyrosogenum, Rhizopus oligosporus and R. stolonifer. Rhizopus spp. were dominant fungi recovered from seeds, followed by Penicillium, Aspergillus, Fusarium and Cylindrocarpon. The fungi detected resulted in decay and rotting of seeds, and thereby reducing percentage germination of seeds (22%, 37% and 63 % seed germination in Black eye, ER7 and Tswana varieties of cowpea respectively). Out of four fungicides tested, benlate, captan, dithane M 45 and chlorothalanil. Dithane M45 effectively controlled seed-borne fungi, and enhanced seed germination to an average of 86% (93% germination with no fungi detected in Tswana variety) as compared to chlorothalonile (79%), benlate and captan (77%) and un-treated seeds (45%). The fungal incidence was reduced to 2.3%, 4.3%, 5.3% and 5.3% when seeds were treated with dithane M-45, chlorothalonil, benlate and captan respectively as compared to 62% in non-treated seeds.

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