WCHR Home WCHR 1 WCHR 2 WCHR 3 WCHR 4 WCHR 5 Search
Serge Gudin
Meilland Star Rose - Domaine Saint André 83340
- Le Cannet des Maures (France)
<
- Le Cannet des Maures (France)
I. INTRODUCTION
A recent review about rose breeding (1) brings evidence that roses are the most anciently produced and continue to be one of the most appreciated ornamentals. Cut rose greenhouse production areas worldwide reached more than 5,250 ha in 1994 and the average price in the Dutch auction system in 1994 was 0.27 and 0.17 U.S.D. per stem for long, and medium and short stemmed cultivars respectively (2). There is also a very substantial market for garden rose bushes in developed countries. Approximately 20 million plants per annum are sold in the United Kingdom (3). Furthermore, there are currently millions of miniature pot roses sold every year (4). Roses are also one of the major flowers used for the perfume industry and they are important for their medicinal and culinary qualities (5).
Although there are about 200 species of Rosa, it is admitted that only 1 1 of them contribute to the origin of modern cultivars (see 1).
The aim of the present article is to deal briefly with the new
international challenges, the past and present of rose breeding
research, and the main rose research groups and their current
interests, in order to give conclusions about some scientific
perspectives.
II. THE MAIN INTERNATIONAL CHALLENGES
One of the main changes at the international level RONG>
One of the main changes at the international level in cut rose production during these last few years is - as for many other horticultural crops - the rapid development of new areas of production, mainly in developing countries, for obvious economical reasons. Cut rose greenhouse areas in tropical regions of America and Africa have for instance increased from 363 ha in 1985 to more than 1100 ha in 1994 (see 2). This change has of course led to an evolution of these new growers' demand concerning the technical aspects of varieties. Thus, the importance of postharvest quality and thornlessness have specially been stressed because of the transportation. Varieties with good low temperature growing ability have been requested in Latin America. Indeed, in these tropical zones, roses are mainly grown at high altitudes (2300 -3000 m) - characterized by cold nights, in Colombia, Ecuador and Mexico.
In order to overcome this new competition some of the "older" growing countries, especially the leading one in rose production, the Netherlands, have reacted in intensifying and "artificializing" their production. Soilless cultivation, artificial lighting, high heating, C02 addition, computerized regulation of greenhouse climate, use of bunching robots have developed. This has led to tremendous differences in greenhouse investment costs between Dutch and "tropical" systems, the former being 200-300 U.S.D. x m-2, the latter rmer being 200-300 U.S.D. x m-2, the latter one being of 20-50 U.S.D.x m-2 (6). The intensification tendency occurring in developed countries - mainly in Northern Europe - has also led to new demands in terms of varieties. Thus, varieties reacting well to the new plant management known as "bending" (see 7, 8), or on their own roots (so that they can be cheaply propagated by cutting), have been objects of search. At the same time these European growers, probably in order to keep novelty as a strategic marketing advantage, undertake varietal renewal faster than ever in their greenhouses. Nowadays, many Dutch growers renew their plantations every three years, whereas they renewed them every five years some ten years ago. This actually leads to a very quick turn-over of the plants and varieties. This is also true for the new understock varieties that North European and lsraelian propagators promote more and more rapidly in order to differenciate themselves from their competitors.
Another type of noticeable change is the development of new consuming countries. Sometimes, these countries began as primarily producing roses for exportation, such as Mexico or South Africa. Nowadays, their national market is considerable. Probably almost 70 % of the roses produced in Mexico are, for instance, now sold on the national market, whereas almost all of them were exported some fifteen years ago. There are some expectations that India coago. There are some expectations that India could make this kind of move in the future. Other new consuming countries are appearing, such as Russia, many other ex-soviet and eastern block countries, and Argentina. These countries mainly import the roses they need for their markets - Russia has thus become one of the main importing countries in the world. Many of them are beginning to organize local production aiming at selling in their newly emerging national markets. Some rose greenhouses have, for instance, been planted in Kazakstan last year !
Garden rose research is very much influenced by the worldwide growing concern for environment preservation. Many new varieties are primarily selected for their high tolerance to parasites, so that they need only very few or no pesticide sprays. Furthermore, probably due to the development of the use of roses in large scale landscaping, some varieties are selected for their good growth on their own roots. They can thus be more cheaply propagated in large numbers by cuttings. Moreover, this increased use in landscaping results in a growing demand for multi-use varieties. Thus, a landscape variety will often be also selected because of the esthetic value of its hips in winter time, or because of its rambling ability - making it useful as a natural fence ...
Up to now, there has been, to our knowledge, no breeding of roses
specially dedicated to the perfume industry. This results fromcated to the perfume industry. This results from
the fact that these roses are mostly grown in zones with out or
with ineffective plant breeder right laws (in Eastern Europe or
Western Asian countries). These countries export to the manufacturing
countries partially preprocessed products such as attar, concrete
or absolute. Moreover, up to now, plant protection laws only protected
the plants themselves or the plant parts that can be used for
clonal propagation. The recent law evolution that now protects
all plant parts and also the products resulting from first transformation
(see the "Journal officiel des Communaut6s europ6ennes, 119194,
no 227, pp. 1-30) could bring a new interest from the breeders
for perfume roses.
III. ROSE BREEDING RESEARCH IN THE PAST
Rose species introductions in the western world since antiquity and intensive rose breeding since the 18 th century are of common knowledge. However, published literature about rose genetics is relatively rare. Rose breeding is mainly carried out by highly competitive private companies and their applied genetic knowledge is proprietary and unpublished (see 9; 1 0). Furthermore, some technical factors make the rose a difficult model system for geneticists. It has indeed high heterozygotic (see 1 1 1 0) and ploidy levels (11; 12), plus wellknown difficulties in sexual reproduction, from pollination to seed germination (1).
on, from pollination to seed germination (1).
Although rose chromosomes have often been reported as small and difficult to observe through classical procedures, many cytological studies have been carried out since the 1920s, and up to now (see 1, for review). In that respect, the pionneer works of Tdtckholm (13) and Hurst (14, 15) should be cited for their historical importance.
The large majority of modern rose cultivars are tetraploids while some wild diploid species have long been described as potential sources of resistance to fungal diseases, such as blackspot (16,, 17). Different attempts were made in order to use this "wild" germplasm. Crosses made between diploid species and tetraploid cultivars logically led to sterile tripioids (18). Attempts at chromosome doubling by colchicine treatments (19,, 20; 21) have led to very limited results because of poor regeneration and high occurrence of chimerism in the obtained material (21).
Although among the 18000 rose cultivars listed by Hareing (22) almost 10% are spontaneous sports, the numerous induced mutation breeding projects carried out from the 1960s to the 1980s (see 1, for review) only led to a very few cultivars (23).
Little is really known (or published ?) about the genetic control of morphological or physiological characters of roses. Thanks to some reports (24), (25), (26, 27), (28), (29, 30), (31), (32), some knowledge in that respect is availabl32), some knowledge in that respect is available concerning male sterility (encountered among some Rosa setigera individuals), recurrent flowering , flavonoid pigmentation, winterhardiness and dwarfness. Some results (33) have suggested the existence of close links between the genes controlling petal numbers, petal colors, and dwarf ness (1).
Studies in the 1990s have developed new basic knowledge concerning pollen, pollination, seed maturation and germination (10), and should help to better control hybridization.
Interesting selection procedures have been described, enabling
early prediction of flower productivity (34; 35), using in
vitro tests of disease resistance (36), using unexploited
wild species (37, 38) or amphidipioids (26) as progenitors.
IV. ROSE BREEDING RESEARCH IN THE 1990s - CURRENT STATUS.
Cytological studies are nowadays replaced by genomic analysis using molecular markers. The use of RFLP was first reported by a team, in the USA (39; 40). Then, in Spain, isozyme and RAPD markers were investigated (41), the best characterization resulting from the latter technique (42). RAPD has lately been the most investigated technique - in Spain (43), France (44), the USA (45), and in Germany (46). In lsrael, DNA fingerprinting was used, leading to extremely precise characterization (47 ; 48). Application studies of AFLP Tm are underway in France (sApplication studies of AFLP Tm are underway in France (see Zhang and Reynders - Aioisi, cited in 1) and the Netherlands (Dubois, personal communication). Apart from being a new characterization tool, complementary to the morphological description of newly introduced cultivars, which will help to better defend breeder's rights, the molecular approach is of course promising in terms of future possibilities for the development of efficient molecular marker assisted selection. As demonstrated (44, 43), it should also be of great help to complete and clarify Rosa botanical classification, which is still far from being satisfactory (see 44). Other descriptive attempts are underway in France, using new means such as flow cytometry for ploidy level determination (49; 12), statistical analysis of floral phenolic compounds (50), computerized canonical discriminant analysis and cluster analysis of phenotypic data (51). Furthermore, better harmonization of descriptions should be achieved thanks to the common and associated efforts of the European rose scientific community (52" 53).
All of this characterization work should soon be used by breeding teams willing to explore the yet unexploited germplasm of Rosa. For instance, teams in England (54), Poland (55), France (56; 57), and the USA (58), have established new in vitro and/or in vivo tests and screened large populations for their tolerance / resistance to blackspot, stheir tolerance / resistance to blackspot, stem dying, botrytis blight, powdery mildew, downy mildew, and crown gall diseases and to a nematode (Meloidogyne hapia).
Success in interspecific hybridization is therefore becoming critical. New projects in this area along with published reports would represent important contribution. Although early embryo rescue was first reported on cherry - a Rosaceae (59), published results concerning the use of this technique in roses were only available in 1994 (60; 61; 62). It resulted in the production of an original interspecific hybrid :R.rugosa x R. foetida
When interspecific hybridization is unsuccessful one can turn towards protoplast fusion technology, studied on roses by an English team (63; 64). As for ploidy level manipulation, after unsuccessful haploidization attempts by anther, microspore, or ovule culture in the late 1980s (Gudin, unpublished), the French team of Meynet et al. (62) succeeded in haploidizing in 1994 a tetraploid cultivar through parthenogenesis induced by using irradiated pollen and in vitro embryo rescue. The resulting haploidized plants (diploids) were able to produce flowers and pollen (65). Some of them are fertile (Meynet, personal communication). Gene transfer from diploid species to haploidized cultivars could be envisioned, as well as polyploidization of haploidized plants in order to obtain homozygotes. A recent cols in order to obtain homozygotes. A recent colchicine treatment developed by an American team, through agitation of excised nodes in a colchicine solution or tissue culture of shoots on a medium supplemented with colchicine, seems to be more efficient than previous methods (66). This same American team is using the amphiploid strategy in order to develop blackspot resistant rose germplasm (58).
Professor Zieslin's group in Israel, after having worked many years on phyllody in rose flowers (see 67), is on the edge of demonstrating the genetic control of this type of abnormal floral development (Zieslin, personal communication).
Following the pioneer work of Hill (68) who was the first to observe morphogenesis of shoot primordia on rose callus, many teams in England, Belgium, U.S.A., the Netherlands, France, and Japan achieved successful plant regeneration through organogenesis or somatic embryogenesis (see 1 for review). Regeneration from calluses is one of the few subjects about which private teams, some-times associated with University researchers, have published (see 69; 70; 33; 71). Arene et al. were the only ones to demonstrate in those systems the occurrence of somacional variation, up to a level of 21.7 % (33), therefore demonstrating that they can be used as an efficient creation tool, if combined to selection pressures managed in vitro (see 10).
There is little published work about transformation in Ris little published work about transformation in Rosa. Different
teams in the Netherlands (72), the USA (73), and France (74),
have obtained transformed plants. However, if these works clearly
demonstrated that rose transformation is feasible, they also showed
how many steps need to be controlled before the technique can
be efficiently used in breeding. Not only no "useful"
transformation was achieved, but the transformed plants were chimaeric,
resulting from callus regeneration - and therefore not avoiding
aside transformation the occurence of somaclonal variation (74).
Ongoing transformation work in the Netherlands seems to confirm
that up to now, transformed cells cannot undergo direct plant
regeneration and therefore, unfortunately, have to go through
a callus phase (Dubois, personal communication). Although there
have been to our knowledge no published results, a private biotechnology
company Calgene Pacific formerly, Florigene - clearly anounced
it was undertaking transformation to achieve a blue rose, by transferring
the petunia gene(s) coding for delphinidine (75). However, in
this example, even if transformation and transformed plant regeneration
are successfully handled, one can wonder how interfering factors
such as co-pigmentation and vacuolar pH and "gene silencing"
(76) will affect the final result...
V. CONCLUSION.
Various biotechnology techniques are cRONG>.
Various biotechnology techniques are currently available for rose breeding. However, some of these new techniques have only been applied recently to Rosa and therefore need further research before they can be used with full efficiency. Furthermore, as a tremendous pool of variation is available in yet unexploited Rosa spp., traditional hybridizing will undoubtedly still be a favored mean of improvement.
In any case, increased knowledge in Rosa basic genetics is urgently needed. Ongoing work such as haploidization and genome molecular identification represent great potentials in that respect.
Although cut rose production is increasingly growing in the tropics,
there are to our knowledge almost no published scientific works
available dealing with rose plant physiology or development under
these conditions. The main breeding companies have already organized
in the last five years varietal testing networks in these zones.
Hopefully, cooperation with local scientists will occur in a near
future. They should lead to a better understanding and definition
of specific aims for improvement.
REFERENCES
1. Gudin, S. 1998. Rose : genetics and breeding. Plant Breed. Rev. In press.
2. Pertwee, J. 1995. Production and marketing of roses. Second Edition. Pathfast Publishing. Frinton on Sea. U.K. 127p.
3. Roberts, A.V. and R. Lewis. 1996.on Sea. U.K. 127p.
3. Roberts, A.V. and R. Lewis. 1996. Rose phenotypes , questions of diversity and development. Acta Hort. 424 : 313-319.
4. Borch, K., M.H. Williams and L. Hoyer. 1996. Influence of simulated transport on postharvest longevity of three cultivars of miniature potted rose. Acta Hort. 424 - 175-180.
5. Shepherd, R.E. 1954. History of the rose. Macmillan Publishing Co., Inc. New York. 264 p.
6. Zieslin, N. 1996. Influence of climatic and socio-economical factors on mode of cultivation and research of rose plants. Acta Hort. 424 - 21-22.
7. Kool, M.T.N. 1996. System development of glasshouse roses. PhD Thesis. University of Wageningen. The Netherlands. 143p.
8. Gudin, S. and Coulon, A. 1998. A comparison of five plant management methods in cut rose production, using or not the bending technique. HoriTechnology. In press.
9. De Vries, D.P. and L.A.M. Dubois. 1996. Rose breeding : past, present, prospects. Acta Hort. 424 : 241-248.
10. Gudin,S. and J. Mouchotte. 1996. Integrated research in rose improvement - a breeder's experience. Acta Hort. 424 : 285-292.
11. Berninger, E. 1992. Le rosier de serre pour fieurs A couper. p. 490-504. In : A. Gailais and H. Bannerot (Eds.). Amélioration des espibces végétales cultivées. Paris.
12. Jacob, Y., C. Teyssier, S.C. Brown and S. Reynders-Aloisi. 1996. Use of cytometry for the rapid determination of pioidi. 1996. Use of cytometry for the rapid determination of pioidy level in the genus Rosa. Acta Hort. 424 : 273-278.
13. Täckholm, G. 1922. Zytologische studien Ober die Gattung Rosa. Acta Horti Berg.7, 97-381.
14. Hurst, C.C. 1925. Chromosomes and characters in Rosa and their significance in the origin of species. Experiments in Genetics. 37 , 534-550.
15. Hurst, C.C. 1927. Differential polyploidy in the genus Rosa L. Verhandiungen des V.1nternationalen Kongresses fur Vererbungswissenschaft. 867-906.
16.Paimer, J.G., P. Semeniuk and R.N. Stewart. 1966. Roses and blackspot. 1. Pathogenicity to excised leaflets of Diplocarpon rosae from seven geographic locations. Phytopath. 56 - 1277-1282.
17. Saunders, P.J.W. 1970. The resistance of some cultivars and species of Rosa to Diplocarpon rosae Wolf causing blackspot disease. The Rose Annual. 1 1 8-128.
18. Wylie, A.P. 1955a. The history of garden roses, Part 2. J. Roy. Hort. Soc. 79 - 8-24.
19. Semeniuk, P. and T. Arisumi. 1968. ColChicine- induced tetrapioid and cytochimeral roses. Bot. Gaz. 129 -190-193.
20. Basye, R. 1990. An amphidipioid of Rosa banksiae and RR. laevigata induced by colchicine. Amer. Rose Ann. 75,. 82-88.
21. Roberts, A.V., D. Lloyd and K.C. Short. 1990. In vitro procedures for the induction oftetrapioidy in a diploid rose. Euphytica. 49 : 33-38. induction oftetrapioidy in a diploid rose. Euphytica. 49 : 33-38.
22. Haring, P.A. 1986. Modern Roses 9. American Rose Society (Ed.). Shreveport. U.S.A.
23. Maluszynski, M., B. Sigurbj6rnsson, E. Amano, L. Sitch and 0. Kamra. 1992. Mutant varieties - Data bank FAOI]AEA data-base. Part 11. Mutation Breed. Newsletter. 39 :14-33.
24. Lewis, W.H. and R.E. Basye. 1961. Analysis of nine crosses between diploid Rosa species. Proc. Amer. Soc. Hort. Sci. 78 : 573-579.
25. Semeniuk, P. 1971. Inheritance of recurrent blooming in Rosa wichuraiana. J. Hered. 62 , 203-204.
26. Svejda, F. 1977. Breeding for improvement of flowering attributes of winterhardy Rosa kordesii Wuiff hybrids. Euphytica. 26 - 703-708.
27. Svejda, F. 1979. Inheritance of winterhardiness in roses. Euphytica. 28 .. 309-314.
28. De Vries, D.P. and L.A.M. Dubois. 1978. On the transmission of the yellow flower colourfrom Rosa foetidato recurrent flowering hybrid tea-roses. Euphytica. 27 - 205-10.
29.De Vries, D.P., H.A. Van Keuien and J.W. De Bruyn. 1974. Breeding research on rose pigments. 1. The occurence of flavonoids and carotenoids in rose petals. Euphytica. 23 . 447-457.
30. De Vries, D.P., F. Garretsen, L.A. Dubois and H.A. Van Keuien. 1980. Breeding research on rose pigments. 11. Combining ability analyses of variance of four flavonoids in Fl populations. Euphytica. 20 :115-120.
31. M flavonoids in Fl populations. Euphytica. 20 :115-120.
31. Marshall, H.H., C.G. Campbell and L.M. Collicutt. 1983. Breeding for anthocyanin colors in Rosa. Euphytica. 32 : 205-216.
32. Dubois, L.A.M. and D.P. De Vries. 1987. On the inheritance of the dwarf character in Polyantha X Rosa chinensis minima (Sims) Voss Fl - populations. Euphytica. 36 , 535539.
33. Arene, L., C. Pellegrino and S. Gudin. 1993. A comparison of the somacionai variation level of Rosa hybrida L. cv Meirutral plants regenerated from callus or direct induction from different vegetative and embryonic tissues. Euphytica. 71 - 83-90.
34. De Vries, D.P. 1976. Juvenility in hybrid tea-roses. Euphytica. 25 - 321-328.
35. De Vries, D.P., L.A. Dubois and L. Smeets. 1978. Hybrid tea-roses under controlled light conditions. 3. Flower and blind shoot production in the glasshouse of seedlings selected for flowering or flower bud abortion at low irradiances in a growth room. Neth. J. Agric. Sci. 26 , 399-404.
36. Knight, C. and B.E.J. Wheeler. 1978. Evaluating resistance of roses to blackspot. Phytopath. Z. 91 . 218-229.
37. Buck, G.J. 1960. Progress report on breeding hardy everblooming roses. Amer. Rose Ann. 45: 95-99.
38. Marshall, H.H. 1973. Rose breeding for the prairies. Canada Agriculture. 18 : 24-25.
39. Rajapakse, S., M. Hubbard, J.W. Keiiy, A.G. Abbott and R.E. Ballard. 1992. Identification of rose c, A.G. Abbott and R.E. Ballard. 1992. Identification of rose cultivars by restriction fragment length polymorphism. Scientia Hort.52 -237-245.
40. Hubbard, M., J. Kelly, S. Rajapakse, A.G. Abbott and R.E. Ballard. 1992. Restriction fragment length polymorphisms in rose and their use for cultivar identification. HortScience. 27, 172-173.
41. Torres, A.M., T. Millan and J.1. Cubero. 1993. Identifying rose cultivars using random amplified polymorphic DNA. HortScience. 28 : 333-334.
42. Cubero, J.1.. T. Millan, F. Osuna, A.M. Torres and S. Cobos. 1996. Varietal identification in Rosa by using isozyme and RAPD markers. Acta Hort. 424 , 261-264.
43. Moreno, M.T., A.M. Torres, T. Millan, J. Armada and J.1. Cubero. 1996. Use of molecular markers in taxonomic studies of Rosa sp. Acta Hort. 424 : 293-296.
44. Reynders-Aioisi, S. and P. Bollereau. 1996. Characterization of genetic diversity in genus Rosa by randomly amplified polymorphic DNA. Acta Hort. 424 , 253-260.
45. Ballard, R., S. Rajapakse, A. Abbott and D. Byrne. 1996. DNA markers in rose and their use for cultivar identification and genome mapping. Acta Hort. 424 - 265-268.
46. Debener, T. and L. Mattiesch. 1996. Genetic analysis of molecular markers in crosses between diploid roses. Acta Hort. 424 : 249-252.
47. Vainstein, A. and H. Ben-Meir. 1994. DNA fingerprinting analysis of roses. J. Amer. Soc. Hort. Sci. 119 : 1099-1ing analysis of roses. J. Amer. Soc. Hort. Sci. 119 : 1099-1103.
48. Vainstein, A., H. Ben-Meir, A. Zuker, A.A. Watad, G. Scovel, A. Ahroni and M. Ovadis. 1995. Molecular markers and genetic transformation in the breeding of ornamentals. Acta Hort. 420 ; 65-67.
49. Demilly, D., B. Billy, M. Lemaire and Y. Dattee. 1994. Dénombrement du genre Rosa, collection de la roseraie. Colloque du centenaire de la roseraie de Val-de-Marne. Les avancées scientifiques et techniques dans le genre Rosa. (Recueil des actes). p. 85-95.
50. Raymond, 0., J.P. Biolley and M. Jay. 1994. Exploitation statistique de la distribution des composés phénoliques floraux en vue de la compréhension du processus de domestication chez le rosier. Colloque du centenaire de la roseraie du Val-de-Marne. Les avancées scientifiques et techniques dans le genre Rosa. (Recueil des actes). p.3567.
51. Teyssier, C., S. Reynders-Aioisi and Y. Jacob. 1996. Characterisation of a collection of botanical rose trees by phenotypic analysis. Acta Hort. 424 : 302-308.
52. Gandelin, M.H. and M.N. Mistou. 1994. Harmonisation des descriptions de variétés de rosier au plan national et international. Coiioque du centenaire de la roseraie du Valde-Marne. Les avanc6es scientifiques et techniques dans le genre Rosa. (Recueil des actes). p. 113-133.
53. Mistou, M.N., M.H. Gandelin and L. Poetto. 1996. National rose gr.N., M.H. Gandelin and L. Poetto. 1996. National rose group - census of varieties and harmonization of descriptions. Acta Hort. 424 : 297-300.
54. Walker, S., Z. Mandegaran and A.V. Roberts. 1996. Screening roses for resistance to Diplocarpon rosae. Acta Hort. 424,. 209-214.
55. Wisniewska-Grzeszkiewicz, H. and A.T. Wojdyla. 1996. Evaluation of rose cultivars to fungal diseases susceptibility. Acta Hort. 424 : 223-236.
56. Reynders-Aloisi, S., G. Pelioli and A. Bettachini. 1996. Analysis of the behaviour of various rootstocks and botanical species of the genus Rosa towards Agrobacterium tumefaciens. Acta Hort. 424: 215-220.
57. Voisin, R., J.C. Minot, D. Esmenjaud, Y. Jacob, G. Pelioli and S. Aloisi. 1996. Host suitability of rose rootstocks to the root-knot nematode Meloidogyne hapia using a high inoculum-pressure test. Acta Hort. 424 , 237-240.
58. Byrne, D.H., W. Black, Y. Ma and H.B. Pemberton. 1996. The use of amphidiploidy in the development of blackspot resistant rose germplasm, Acta Hort. 424 ' 269-272.
59. Tukey, H.B. 1933. Artificial culture of sweet cherry embryos. J. of Heredity. 24 : 7-12.
60. Gudin, S. 1994. Embryo rescue in Rosa hybrida L. Euphytica. 72: 205-212.
61. Marchant, R., J.B. Power, M.R. Davey and J. Chartier-Hollis. 1994. Embryo rescue, for the production of Fl hybrids, in English rose. Euphytica, 74 : 187-193.
on of Fl hybrids, in English rose. Euphytica, 74 : 187-193.
62. Meynet, J., R. Barrade, A. Duclos and R. Siadous. 1994. Dihaploid plants of roses (Rosa X hybrida) obtained by parthenogenesis induced using irradiated pollen and in vitro culture of immature seeds. Agronomie. 2 -169-175.
63. Matthews, D., J. Mottley, 1. Horan and A.V. Roberts. 1991. A protoplast to plant system in roses. Plant Cell, Tiss. and Org. Cult. 24: 173-180.
64. Mottley, J., K. Yokoya, D. Matthews, J. Squirrell and J.E. Wentworth. 1996. Protoplast fusion and its potential role in the genetic improvement of roses. Acta Hort. 424 , 389392.
65. Meynet, J., E. Botton, J. Eychene and F. Aime. 1996. optimization of a method for the haploidization of cultivated roses. Acta Hort. 424 : 399-401.
66. Ma, Y., D.H. Byrne and J. Chen. 1997. Amphidiploid induction from diploid rose interspecific hybrids. HortScience. 32 : 292-295.
67. Mor, J. and N. Zieslin. 1992. Phyllody malformation in flowers of Rosa X hybrida cv Motrea - effects of rootstocks, flower position, growth regulators and season. J. Experim. Bot. 43 - 89-93.
68. Hill, G. P.1967. Morphogenesis of shoot primordia in cultured stem tissue of a garden rose. Nature. 216 . 596-597.
69. Burger, D.W., L. Liu, K.W. Zary and C.1. Lee. 1990. Organogenesis and plant regeneration from immature embryos of Rosa hybrida L. Plant Cell, Tiss. and Org. ryos of Rosa hybrida L. Plant Cell, Tiss. and Org. Cult. 21 -147-152.
70. Noriega, C. and M.R. S6ndahi. 1991. Somatic embryogenesis in hybrid tea roses. Biotechnology. 9 : 991-993.
71. Moyne, A.L., F. Souq, L.H. Yean, S.C. Brown, M. Boulay and B.S. Sangwan-Norreel. 1993. Relationship between cell pioidy and regeneration capacity of long term Rosa hybrida cultures. Plant Science. 93 :159-168.
72. Van der Mark, F., J.P. Pijnacker-Hordijk, G.A.1. Varega, D.P. de Vries and J.J.M. Dons. 1990. In vivo transformation of clonal Rosa canina rootstocks with Agrobacterium rhizogenes. J. Genet and Breeding. 44 - 263-268.
E., Y. Moy, N. Courtney-Gutterson and R. Robinson. 1994. transgenic rose (Rosa hybrida) from embryogenic tissue.
73. Firoozabady, E., Y. Regeneration of transgen BioTechnologie. 2 - 609-613.
74. Souq, F., P. Coutos-Thevenot, H. Yean, G. Deibard, Y. Maziere, J.P. Barbe and M. Boulay. 1996. Genetic transformation of roses, two examples : one on morphogenesis, the other on anthocyanin biosynthetic pathway. Acta Hort. 424 : 381-388.
75. Dailing, M. 1991. Color it blue. Amer. Rose Magazine. Nov. pp.32-33.
76.Stam, M., J.N.M. Moi and J.N.M. Kooter. 1997. The silence of genes in transgenic plants. Annals of Botany. 79 , 3-12.