scholarly journals CONTEMPORARY APPROACHES TO CITRUS CULTIVAR IMPROVEMENT

HortScience ◽  
1992 ◽  
Vol 27 (6) ◽  
pp. 699b-699
Author(s):  
Frederick G. Gmitter
Keyword(s):  
Genetic Manipulation ◽  
Plant Size ◽  
Citrus Breeding ◽  
Technological Developments ◽  
Citrus Cultivar ◽  
Nucellar Embryony ◽  
Induced Mutagenesis ◽  
Transformation Methods ◽  
Selection Of

Traditional methods of genetic manipulation have proven ineffective or irrelevant for many citrus breeding objectives. Alternative approaches to genetic improvement of citrus are now available as a result of technological developments in genetics and tissue culture. Mapping DNA markers on the Citrus genome should lead to identification of markers closely linked to important loci, thereby facilitating early selection and minimizing costs associated with plant size and juvenility. Genetic transformation methods provide opportunities for trait-specific modification of commercial cultivars. The selection of beneficial variants from sectored fruit chimeras, and the recovery of plants via somatic embryogenesis, can overcome the problems of nucellar embryony and the hybrid nature of commercial cultivar groups. Induced mutagenesis, using mature vegetative buds, may overcome size and juvenility, as well as nucellar embryony and hybridity. Ploidy level manipulation in vitro provides methods to overcome sterility, incompatibility, and nucellar embryony, and it can increase the number and diversity of tetraploid breeding parents available for development of seedless citrus triploids.

scholarly journals Contemporary Approaches to Improving Citrus Cultivars

1994 ◽  
Vol 4 (3) ◽  
pp. 206-210 ◽  
Author(s):  
Frederick G. Gmitter
Keyword(s):  
Genetic Manipulation ◽  
Plant Size ◽  
Citrus Breeding ◽  
Cultivar Groups ◽  
Technological Developments ◽  
Nucellar Embryony ◽  
Induced Mutagenesis ◽  
Alternative Approaches ◽  
Transformation Methods

Traditional genetic manipulation methods have proven ineffective or irrelevant for many citrus breeding objectives. Alternative approaches to Citrus genetic improvement are now available as a result of technological developments in genetics and tissue culture. For example, mapping DNA marker polymorphisms should lead to identifying markers closely linked to important loci, thereby facilitating early selection and minimizing costs associated with plant size and juvenility. Genetic transformation methods allow trait-specific modification of commercial cultivars. By selecting beneficial variants from sectored fruit chimeras and the recovering plants via somatic embryogenesis, the problems of nucellar embryony and the hybrid nature of commercial cultivar groups can be avoided. Induced mutagenesis from mature vegetative buds may overcome these problems, as well as juvenility. Ploidy level manipulation in vitro can increase the number and diversity of tetraploid breeding parents, leading to the development of seedless Citrus triploids and mitigating sterility, incompatibility, and nucellar embryony.

Investigations on the regeneration ability of squash cultivars

2010 ◽  
Vol 58 (2) ◽  
pp. 159-166 ◽  
Author(s):  
E. Kiss-Bába ◽  
S. Pánczél ◽  
K. Simonyi ◽  
G. Bisztray
Keyword(s):  
Genetic Manipulation ◽  
Regeneration Ability ◽  
Root Induction ◽  
Vegetable Crops ◽  
Shoot Induction ◽  
Regeneration System ◽  
Leafy Shoots ◽  
Suitable Combination ◽  
Transformation Methods

Pumpkin, squash and zucchini are important vegetable crops in tropical and temperate regions. The development of genetic transformation methods offers the potential of introducing valuable traits into these crops. An efficient in vitro plant regeneration system is a critical point for genetic manipulation. The regeneration ability of three Cucurbita varieties was tested on Murashige and Skoog medium supplemented with different growth regulators. Cotyledons of all the varieties were cultured to investigate the effect of 2,4-D (0, 1, 2, 3, 4 mg l −1 ) with or without KIN (0, 0.5, 5 mg l −1 ) and of BA (0, 1, 1.2 mg l −1 ) combined with IAA (0, 0.9, 1, 1.2 mg l −1 ), on the efficiency of shoot induction. Abscisic acid (0.26 mg l −1 ABA) was also added to one medium. To find the most suitable combination for shoot induction, cotyledon segments of the three varieties were also cultivated on media with different concentrations of BA (0–1.2 mg l −1 ) and IAA (0–0.9 mg l −1 ). Shoot induction was achieved via organogenesis in the tested varieties. Leafy shoots were transferred to root induction media. Regenerated plantlets with roots were transferred to sterile soil. This is the first report on in vitro regeneration from cotyledon explants of the pumpkin cultivar Nagydobosi and the pattypan squash cultivar Óvári fehér.

scholarly journals Gene Function Analysis in the Ubiquitous Human Commensal and PathogenMalasseziaGenus

mBio ◽  
2016 ◽  
Vol 7 (6) ◽  
Author(s):  
Giuseppe Ianiri ◽  
Anna F. Averette ◽  
Joanne M. Kingsbury ◽  
Joseph Heitman ◽  
Alexander Idnurm
Keyword(s):  
Gene Function ◽  
Genetic Manipulation ◽  
Function Analysis ◽  
Exogenous Dna ◽  
Melanin Biosynthesis ◽  
Disease Symptoms ◽  
Wide Range ◽  
Transformation Methods ◽  
Gene Function Analysis

ABSTRACTThe genusMalasseziaincludes 14 species that are found on the skin of humans and animals and are associated with a number of diseases. Recent genome sequencing projects have defined the gene content of all 14 species; however, to date, genetic manipulation has not been possible for any species within this genus. Here, we develop and then optimize molecular tools for the transformation ofMalassezia furfurandMalassezia sympodialisusingAgrobacterium tumefaciensdelivery of transfer DNA (T-DNA) molecules. These T-DNAs can insert randomly into the genome. In the case ofM. furfur, targeted gene replacements were also achieved via homologous recombination, enabling deletion of theADE2gene for purine biosynthesis and of theLAC2gene predicted to be involved in melanin biosynthesis. Hence, the introduction of exogenous DNA and direct gene manipulation are feasible inMalasseziaspecies.IMPORTANCESpecies in the genusMalasseziaare a defining component of the microbiome of the surface of mammals. They are also associated with a wide range of skin disease symptoms. Many species are difficult to culturein vitro, and although genome sequences are available for the species in this genus, it has not been possible to assess gene function to date. In this study, we pursued a series of possible transformation methods and identified one that allows the introduction of DNA into two species ofMalassezia, including the ability to make targeted integrations into the genome such that genes can be deleted. This research opens a new direction in terms of now being able to analyze gene functions in this little understood genus. These tools will contribute to define the mechanisms that lead to the commensalism and pathogenicity in this group of obligate fungi that are predominant on the skin of mammals.

scholarly journals Mutagenesis and Biotechnology Techniques as Tools for Selecting New Stable Diploid and Tetraploid Olive Genotypes and Their Dwarfing Agronomical Characterization

HortScience ◽  
2016 ◽  
Vol 51 (7) ◽  
pp. 799-804 ◽  
Author(s):  
Eddo Rugini ◽  
Cristian Silvestri ◽  
Marilena Ceccarelli ◽  
Rosario Muleo ◽  
Valerio Cristofori
Keyword(s):  
Gamma Irradiation ◽  
Reproductive Behavior ◽  
Oil Quality ◽  
Plant Size ◽  
The Self ◽  
Wild Type ◽  
Self Fertilization ◽  
Constant Yield ◽  
Selection Of

In Olea europaea L. subsp. europaea, tetraploid genotypes do not exist in nature. Herein, we report the first example of selection of tetraploid olive plants, obtained by combining physical mutagenesis and biotechnology techniques. Stable tetraploid (4n) and diploid (2n) genotypes were isolated in vitro through shoot-tip fragmentation of two mixoploid mutants derived from the gamma irradiation of self-incompatible Leccino and self-compatible Frantoio cultivars. In this study, the stable mutants FRM5-4n, FRM5-2n, LM3-4n, and LM3-2n were characterized in the field for vegetative and reproductive behavior with the aim to use them as varieties or dwarfing rootstocks. The stable 4n genotype of Leccino acquired self-fertility whereas the 4n Frantoio maintained it. A high and constant yield was showed by LM3-2n during 9 years of observation, maintaining the same oil quality as the Leccino wild type (wt). Moreover, the LM3-2n acquired the capacity to be intercompatible with the diploid mutant Leccino dwarf (LD) and with the Leccino wt. This acquired property would allow for a reduction of heterozygosity in the offspring, if crossed with each other for some generations and with the Leccino wt, because it is a sort of self-fertilization. When used as rootstocks, both 4n and 2n Leccino mutants proved to be very effective for reducing the scion size of the high-vigor Canino cultivar, which is well known for its excellent extravirgin oil. Finally, it was demonstrated that the self-grafting of vigorous cultivar caused a reduction in plant size, thus suggesting that it is possible to produce semidwarf plants from vigorous genotypes to consider them in high-density olive orchards.

scholarly journals Why Is the Correct Selection of Trichoderma Strains Important? The Case of Wheat Endophytic Strains of T. harzianum and T. simmonsii

2021 ◽  
Vol 7 (12) ◽  
pp. 1087
Author(s):  
Alberto Pedrero-Méndez ◽  
H. Camilo Insuasti ◽  
Theodora Neagu ◽  
María Illescas ◽  
M. Belén Rubio ◽  
...  
Keyword(s):  
Indole Acetic Acid ◽  
Plant Protection ◽  
Plant Size ◽  
Correct Selection ◽  
In Vitro Assays ◽  
Phytopathogenic Fungus ◽  
Agricultural Systems ◽  
Biocontrol Potential ◽  
Selection Of

The search for endophytic fungi in the roots of healthy wheat plants from a non-irrigation field trial allowed us to select 4 out of a total of 54 cultivable isolates belonging to the genus Trichoderma, identified as T. harzianum T136 and T139, T. simmonsii T137, and T. afroharzianum T138. In vitro assays against the phytopathogenic fungus Fusarium graminearum showed that the T. harzianum strains had the highest biocontrol potential and that T136 exhibited the highest cellulase and chitinase activities. Production patterns of eight phytohormones varied among the Trichoderma strains. All four, when applied alone or in combination, colonized roots of other wheat cultivars and promoted seed germination, tillering, and plant growth under optimal irrigation conditions in the greenhouse. Apart from T136, the endophytic Trichoderma strains showed plant protection capacity against drought as they activated the antioxidant enzyme machinery of the wheat plants. However, T. simmonsii T137 gave the best plant size and spike weight performance in water-stressed plants at the end of the crop. This trait correlated with significantly increased production of indole acetic acid and abscisic acid and increased 1-aminocyclopropane-1-carboxylic acid deaminase activity by T137. This study shows the potential of Trichoderma endophytes and that their success in agricultural systems requires careful selection of suitable strains.

Reduced-stature Rosa species through in vitro mutagenesis

2012 ◽  
Vol 92 (6) ◽  
pp. 1049-1055
Author(s):  
M. M. Q. Baig ◽  
I. A. Hafiz ◽  
N. A. Abbasi ◽  
M. Yaseen ◽  
Z. Akram ◽  
...  
Keyword(s):  
Gamma Irradiation ◽  
Dose Range ◽  
Plant Size ◽  
Shoot Tips ◽  
In Vitro Mutagenesis ◽  
Recent Trends ◽  
Culture Cycle ◽  
Rosa Species ◽  
Selection Of

Baig, M. M. Q., Hafiz, I. A., Abbasi, N. A., Yaseen, M., Akram, Z. and Donnelly, D. J. 2012. Reduced-stature Rosa species through in vitro mutagenesis. Can. J. Plant Sci. 92: 1049–1055. Plant height is one of the main attributes affecting general appeal and beauty of roses (Rosa spp.). Among the highly scented rose species, R. gruss an teplitz, R. centifolia, and R. borboniana, have great potential horticultural and commercial value. However, their large plant size detracts from recent trends towards selection of smaller plants for emerging markets and high-density plantations. This study aimed to produce reduced-stature plants through in vitro mutagenesis using gamma irradiation (Co60). Shoot tips cut from micropropagated shoots were exposed up to 120 Gy. Irradiated shoot tips were micropropagated for one culture cycle. Surviving shoots were rooted in vitro then acclimatized for 2 mo in a greenhouse. The shoot tip LD50 after gamma irradiation was species-dependent and 33–54 Gy. In this dose range, survival during in vitro rooting and acclimatization was also affected; this was 64 to 24% and 34 to 14% of control values, respectively. Acclimatized transplants were 17 to 56% smaller with 16 to 51% less leaf area compared with the controls. In order to ascertain stability putative reduced-stature roses will be monitored for vegetative and floral characteristics over the next few years. This study adds to the ongoing efforts to obtain reduced-stature rose plants for horticultural purposes.

Clone selection of in vitro horseradish hairy root cultures

Planta Medica ◽  
2015 ◽  
Vol 81 (16) ◽  
Author(s):  
R Bertóti ◽  
Á Alberti ◽  
A Böszörményi ◽  
R Könye ◽  
T Horváth ◽  
...  
Keyword(s):  
Hairy Root ◽  
Hairy Root Cultures ◽  
Root Cultures ◽  
Clone Selection ◽  
Selection Of

Improvement of effectiveness in maize breeding

2006 ◽  
Vol 54 (3) ◽  
pp. 351-358 ◽  
Author(s):  
P. Pepó
Keyword(s):  
Recurrent Selection ◽  
Genetic Manipulation ◽  
Field Testing ◽  
Tissue Cultures ◽  
Maize Breeding ◽  
Breeding Programmes ◽  
Speed Up ◽  
Selection For

Plant regeneration via tissue culture is becoming increasingly more common in monocots such as maize (Zea mays L.). Pollen (gametophytic) selection for resistance to aflatoxin in maize can greatly facilitate recurrent selection and the screening of germplasm for resistance at much less cost and in a shorter time than field testing. In vivo and in vitro techniques have been integrated in maize breeding programmes to obtain desirable agronomic attributes, enhance the genes responsible for them and speed up the breeding process. The efficiency of anther and tissue cultures in maize and wheat has reached the stage where they can be used in breeding programmes to some extent and many new cultivars produced by genetic manipulation have now reached the market.

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