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Citrus grafts
In article ,
wrote... In article , mel turner mturner@sni pthis.acpub.duke.edu writes In article , wrote... A true graft hybrid is a plant that has genetic material from both parents in all cells and which has arisen from cells right at the graft union. True graft hybrids are very rare, because you have to get actual mixing of cell contents and then development of a shoot from these mixed cells. Ummm, I don't think that's accurate. As I recall it, "graft hybrids" are just chimeras, with tissues composed of a mix of cells of both the stock and scion of the original graft union. The cells don't actually fuse, but both cell types take part in the same growing tips that produce the shoots, leaves, flowers, etc. of the "hybrid". Such periclinal chimeras in angiosperms can be quite stable [forming shoots with outer tissues from one "parent" over inner tissues of the other], and graft hybrids will sometimes arise as adventitious buds formed from the graft union tissues. It can be possible to destroy all the lateral buds on a grafted plant, cut it off through the graft union, and get "graft hybrid" shoots regenerating from callus formed from the graft union region. Hybrids formed by somatic cell fusions such as you describe are also possible [especially in laboratory cell cultures], but they're a separate thing from "graft hybrids". I was also of the opinion that graft hybrids and chimeras were the same, but I was recently browsing a book which had them as different. Interesting. What is the distinction? Do non-chimera graft hybrids actually exist, or are they just hypothetical? It appears that the original hypothesis for various plants (Hawthorn/Medlar, Laburnum/Broom) now recognised as chimeras was that they were true hybrids arising from fusion of cells in the graft, and therefore described as "graft hybrids". Okay, but that original hypothesis was incorrect, and "graft hybrids" all turned out to be chimeras, right? Or, if this is not the case, what are some examples of "genuine graft-hybrids"? [I suppose somatic hybrids formed by protoplast fusions and using modern cell culture techaniques could count, but they're not derived from "grafts" in the usual sense]. It would appear that there are two usages for the term "graft hybrid". (And checking B. Daydon Jackson's "A Glossary of Botanic Terms" I find a 3rd - "effect produced by one or other of the united individuals on its grafted fellow" - which would seem to make a fruit tree on a dwarfing rootstock a "graft hybrid".) Again, interesting. Okay, I'll have to look a bit further on this. A web search found this post [to an orchid list] which also says graft hybrids and chimeras are different [but didn't say how]. It also gives a number of references:: ttp://www.potto-webdesign.com/mailman/public/orchids/2003-April/001448.html [begin quote] [OGD] Graft hybridization Hideka Kobayashi hkobayashi4 at yahoo.com Tue Apr 22 18:01:40 CEST 2003 There is no interchange of genetic material. I guess you didn't understand. Although there is no exchange of genetic material, short pieces of RNA can travel through graft or scion, and can interfere expression of traits, etc. Yes, this can be heritable. It's called RNAi (RNA interference). The most recent Nobel Prize (in medicine?) recepients were recognized for their studies on RNAi in C. elegans, etc. These plants are properly called graft chimaeras. Graft chimeras and graft hybrids are not strictly the same. They are often mixed or confused, though. As far as I know, the only documented ones are woody plants. Not so. Could you define "documented"? From a simple search with Agricola: AU: Hirata,-Y.; Motegi,-T.; Takeda,-Y.; Morikawa,-K. TI: Induction of cytoplasmic male sterility in the seed progeny derived from artificially-synthesized interspecific chimera in Brassica. SO: Euphytica. Dordrecht : Kluwer Academic Publishers. 2001. v. 117 (2) p. 143-149. AU: Hirate [sic],-Y.; Noguchi,-T.; Oguni,-S.; Kan,-T. TI: Genetic constitution of germ cells in intervarietal and interspecific chimeras on Brassica induced by in-vitro grafting. SO: Theor-appl-genet. Berlin, W. Ger. : Springer International. Oct 1994. v. 89 (2/3) p. 249-254. AU: Hamaguchi,-H.; Kokubun,-M.; Yoneyama,-T.; Hansen,-A.P.; Akao,-S. TI: Control of supernodulation in intergeneric grafts of soybeans and common beans. SO: Crop-sci. Madison, Wis. : Crop Science Society of America, 1961-. July/Aug 1993. v. 33 (4) p. 794-797. AU: Kaddoura,-R.L.; Mantell,-S.H. TI: Synthesis and characterization of Nicotiana-Solanum graft chimeras. SO: Ann-Bot. London : Academic Press. Dec 1991. v. 68 (6) p. 547-556. AU: Noguchi,-T.; Hirata,-Y.; Yagishita,-N. TI: Intervarietal and interspecific chimera formation by in vitro graft-culture method in Brassica. SO: Theor-Appl-Genet. Berlin, W. Ger. : Springer International. 1992. v. 83 (6/7) p. 727-732. AU: Sharkoff,-J.; Brick,-M.A. TI: Effects of grafting roots and shoots of Phaseolus vulgaris and P. acutifolius on physiological and morphological variables. SO: Annu-Rep-Bean-Improv-Coop. Fort Collins, Colo : Howard F. Schwartz, Colorado State University. 1990. v. 33 p. 190-191. AU: Gordon-Weeks,-R.; White,-R.F.; Pierpoint,-W.S. TI: Evidence for the presence of endogenous inducers of the accumulation of pathogenesis-related (PR-1) proteins in leaves of virus-infected tobacco plants and of an interspecific Nicotiana hybrid. SO: Physiol-Mol-Plant-Pathol. London : Academic Press. May 1991. v. 38 (5) p. 375-392. AU: Lee,-S.H.; Ashley,-D.A.; Boerma,-H.R. TI: Regulation of nodule development in supernodulating mutants and wild-type soybean. SO: Crop-Sci. Madison, Wis. : Crop Science Society of America. May/June 1991. v. 31 (3) p. 688-693. AU: Yagishita,-N.; Hirata,-Y.; Okochi,-K.; Mimura,-K.; Mizukami,-H.; Ohashi,-H. TI: Characterization of graft-induced change in capsaicin content of Capsicum annuum L. SO: Euphytica. Wageningen : Netherlands Study Circle of Plant Breeding. Aug 1985. v. 34 (2) p. 297-301. ill. AU: Pandey,-K-K TI: Genetic transformation and "Graft-hybridization" in flowering plants [Tobacco] SO: TAG-Theor-Appl-Genet, 1976, 47 (6): 299-302. Ref. I found more in the past, but don't have time to do a through search. Brassica, Phaseolus, Glycine, Tobacco, etc are not woody plants. If you try to reproduce it with seeds, you will only get the genetic material from one species. This is the case with simple chimeras like the one you described. Not the ones I mentioned." [end quote] Some more less relevant results from a search of Biological Abstracts: Title: INTERGENERIC HYBRIDS BETWEEN CRATAEGUS AND MESPILUS A FRESH LOOK AT AN OLD PROBLEM. Author, Editor, Inventor: BYATT-J-I; FERGUSON-I-K; MURRAY-B-G Source: Botanical-Journal-of-the-Linnean-Society. 1977; 74 (4): 329-344. Abstract: A brief outline is given of the history and nomenclature of the sexual and graft hybrids (chimeras) between Crataegus and Mespilus. An investigation has been made of some aspects of the macromorphology, the pollen fertility and exine characters, cytology and physiology of the plants growing in the Royal Botanic Gardens, Kew [England]. It is suggested that in the past too much emphasis has been laid on the anatomy of the epidermal layers and the separation of parental characters in chimeras. Observations made during the study show the presence of intermediate characters in the graft hybrid [+ Crataegomespilus] as well as in the sexual hybrid [x Crataemespilus] and there is evidence that most parts of the graft hybrids are probably influenced by both the parental genotypes. Title: THE ALKALOID PATTERN OF THE GRAFT HYBRID LABURNOCYTISUS-ADAMII FABACEAE. Author, Editor, Inventor: GREINWALD-R {a}; WINK-M; WITTE-L; CZYGAN-F-C Source: Biochemie-und-Physiologie-der-Pflanzen-BPP. 1991; 187 (5): 385-391. Language: GERMAN Abstract: The alkaloid pattern of the graft hybrid Laburnocytisus adamii (Laburnum anagyroides + Cytisus purpureus) was analyzed by GC and GC-MS. 14 alkaloids (mostly quinolizidine alkaloids, but also bipiperidyl and pyrrolizidine alkaloids) were identified. Interesting seaonal changes of the alkaloid pattern were observed in leaves. Leaf buds accumulate the highest total alkaloid amount with more than 90% cytisine. During the development of the leaves in spring, a substantial increase of N-methylcytisine was observed. Later in the year, the alkaloid concentration of the leaves strongly declined. The alkaloid pattern did not reflect the hybrid status of Laburnocytisus adamii. It was very close to that of Laburnum anagyroides, while the typical alkaloids of Cytisus purpureus could not be detected. However, remarkable quantitative differences were observed. The alkaloid content of plant parts originating from Laburnum were as high as in Laburnum anagyroides, whereas those originating from Cytisus were rather low. Thus the hybrid status of this plant is both reflected in its morphology and its content of quinolizidine alkaloids. Title: Genetic mosaics and the analysis of leaf development. Author, Editor, Inventor: Marcotrigiano-Michael {a} Source: International-Journal-of-Plant-Sciences. [print] May, 2001; 162 (3): 513-525. Abstract: Genetic mosaics with phenotypic markers can be used to study the development of normal leaves. Mosaics synthesized between normal cells and cells possessing developmental mutations can be used to determine whether or not a mutation acts cell autonomously or if cell- to-cell interactions occur. This article reviews the use of cytochimeras, plastid chimeras, radiation-induced chimeras, and graft chimeras to analyze leaf development in angiosperms and to gain insight into the cell lineage, cell-to-cell communication, and the control of morphology. New data are also presented. Leaves of plastid chimeras and graft chimeras were analyzed to determine the level of cell autonomy in different regions of the leaf blade. Evidence that small populations of leaf cells can act out developmental programs is presented. The relationship of these leaves to concepts such as developmental compartments, organismal theory, and pattern formation is discussed. Title: In vitro neoformation of grape chimeras (Vitis vinifera L.). Author, Editor, Inventor: Verdisson-Sandrine {a}; Baillieul-F; Audran-J-C Source: Journal-International-des-Sciences-de-la-Vigne-et-du-Vin. Jan.-Feb., 1999; 33 (1): 1-7. Language: French; Non-English Language of Summary: English; French Abstract: Difference in grape sensitivity to Botrytis cinerea attacks between cultivars was explained by differences in the epidermic tissue of the fruit Therefore, this work was conducted to create a grape periclinal chimera, whose fruits would combine the skin of a Botrytis tolerant cultivar with a pulp of an another cultivar admitted its good organoleptic quality and productivity. In a first time, graftings of two cultivars (Chardonnay and Pinot noir) were conducted in vitro on 5 different media supplemented with various plant growth regulators. Adventitious shoots were only observed on medium containing BAP and GA3 from a mixed callus structure after four weeks of darkness followed by a light/dark regime. In a second time, RAPD analysis, conducted on these plants, showed their chimerical characteristics. Title: Graft chimeras and somatic hybrids of new cultivars. Author, Editor, Inventor: Lindsay-G-C {a}; Hopping-M-E; Binding-H; Burge-G-K Source: New-Zealand-Journal-of-Botany. 1995; 33 (1) 79-92. Abstract: Three techniques were evaluated as methods for plant improvement: protoplast fusion in vitro for somatic hybrids, protoplast co-culture in vitro for chimeras, and graft manipulation in planta for periclinal chimeras. Methods were developed initially for herbaceous, solanaceous species and then evaluated on two species of woody Actinidia. Protoplasts from tomato (2n = 24) and BU (a Solanum hybrid obtained by fusing nightshade and dihaploid potato protoplasts, 2n = 96) were fused at laboratories located at Kiel, Germany, and Levin, New Zealand. Identical methods were used at each laboratory, and plants were regenerated from the hybrid callus. At Kiel, only 1.6% of the regenerants were symmetric fusions that contained 120 chromosomes. One chimeric plant remained genomically stable during 3 years of in vitro growth and a further year in the glasshouse. At Levin, 83% of regenerants were asymmetric fusions with additional nightshade or Bu genomes. Some regenerants, however, contained a single nightshade genome. Protoplasts from Actinidia were fused using the methods detailed for the solanaceous plants, but regeneration of plants was not achieved. Chimeric plants were obtained by co-culturing Bu and tomato plants. At Kiel, 2.1% of the regenerants were chimeric. Co-cultures of protoplasts between Actinidia arguta and A. deliciosa, at Levin, did not produce regenerative callus. Periclinal chimeras were sought from in planta grafts between tomato and nightshade. Two chimeric shoots were obtained. On the basis of epidermal hair type, pollen compatibility, seed and fruit set, one chimera had the histogenic LI layer of nightshade over LII and LIII histogenic layers of tomato (NTT), and the other had two layers of nightshade over one layer of tomato (NNT). Chimera NTT was more stable than NNT, but both produced axillary shoots with characteristics of the other chimera. Periclinal chimeras were also sought from graft unions in planta and in vitro between A. arguta and A.deliciosa. From in planta grafts, all adventitious shoots were A. arguta. From in vitro grafts, 75% of the shoots that regenerated were A. deliciosa and none was chimeric. Each of these techniques has the potential to produce new plants. However, the probability of success was low and therefore a large number of regenerants would be required from which to select the desired plants. Title: Arrangement of cell layers in the shoot apical meristems of periclinal chimeras influences cell fate. Author, Editor, Inventor: Marcotrigiano-Michael {a}; Bernatzky-Robert Source: Plant-Journal. 1995; 7 (2) 193-202. Abstract: Utilizing a complete set of six periclinal graft chimeras composed of Nicotiana tabacum and Nicotiana glauca (TGG, GTT, TTG, GGT, TGT, and GTG), the fate of the three apical cell layers in both vegetative and reproductive organs has been traced. An analysis of leaf phenotype indicated that only rarely did deviations from expected cell lineage occur and in only TTG did such deviations originate in the shoot apical meristem rather than during leaf development. In most plants that possess a stratified shoot apical meristem, gametes are derived from the second apical layer (L2). A phenotypic and/or DNA analysis of seed progeny following reciprocal crosses between all chimeras and their component species indicated that pollen and eggs were sometimes derived from non-L2 lineage in all but one periclinal chimera. There was no evidence for non-L2-derived gametes in 95 crosses where GTT was a parent whereas 40 of 104 crosses with TTG as a parent yielded some offspring that resulted from non-L2-derived gametes. Of these 40 cases, non-L2-derived pollen grains were responsible 39 times while non-L2-derived eggs were responsible just once. Therefore, the occurrence of non-L2-derived gametes was not random. The disruption of 'normal' lineage patterns was dependent on the specific arrangement of genetically dissimilar tissue layers in the shoot apices of the chimeras and was different for different organs. Interestingly enough, Citrus grafts come back into the pictu Title: Interactions between different genotypic tissues in citrus graft chimeras. Author, Editor, Inventor: Zhou-Jinmei; Hirata-Yutaka {a}; Nou-Ill-Sup; Shiotani-Hiroshi; Ito-Tsutau Source: Euphytica-. [print] 2002; 126 (3): 355-364. Abstract: Citrus chimeras NFF (layer constitution: L1-L2-L3=NFF) and FNN (layer constitution L1-L2-L3=FNN) were periclinal chimeras, produced by grafting of Citrus sinensis cv. Fukuhara orange (F) and C. natsudaiddai cv. Kawano natsudaidai (N). Some characters of F or N, such as the color of epicarp and juice sacs of fruits, developed independently in their chimeras, while other characteristics, including leaf size and stoma size, sugar content, acidity and size of the fruits in the chimeras displayed interactions between the two genetically different tissues, i.e., the 'exogenous' epidermis (L1) in the chimeras imposed effect on the quantitative characters that were inner tissue derived or determined of making them oriented to those of its (L1) donor plant. So did the inner tissues to the L1-determined or derived traits. Cell displacement occurred during leaf development in the NFF chimera and cell replacement in both chimeras occurred during fruit development. Peroxidase analysis revealed that each donor plant had one unique band. The N-peroxidase band was stably detected in both chimeras. This band could thus be used as a reliable marker of N tissue in chimeric plants. No chimera specific isozyme band was detected. RAPD analysis, however, showed the presence of chimera specific bands besides the donor specific bands. This suggests that interactions between genotypically different cells caused variation(s) at the DNA level, and thus could be a source of genetic variation(s). Title: Histogenic identification by RAPD analysis of leaves and fruit of newly synthesized chimeric Citrus. Author, Editor, Inventor: Sugawara-Kuniaki {a}; Wakizuka-Takumi {a}; Oowada-Atsushi {a}; Moriguchi-Takaya; Omura-Mitsuo Source: Journal-of-the-American-Society-for-Horticultural-Science. [print] January, 2002; 127 (1): 104-107. Abstract: Randomly amplified polymorphic DNA (RAPD) analysis was used to investigate the histogenic structure of leaf and fruit tissues in four graft chimeras, two intentional chimeras that were produced in combination with 'Hamlin' orange (Citrus sinensis (L.) Osbeck) and 'Satsuma' mandarin (C. unshiu Marc.), and two naturally occurring periclinal chimera cultivars, Kobayashi Mikan (a graft chimera of C. unshiu and C. natsudaidai Hayata), and Kinkoji Unshu (a graft chimera of C. unshiu and C. obovoidea hort. ex Takahashi). RAPD profiles of the lamina epidermis and the mesophyll cells of specific individuals indicated that the four graft chimeras were interspecific monekto chimeras, whose outermost layer (histogenic layer L-1) of the shoot apical meristem consisted of a species that was different from that in the inner layers (histogenic layers L-2 and L-3). Moreover, juice vesicles, which develop from the inside cells of the pericarp and become the main edible parts of Citrus fruit, were a mixture of the cells from both parental source cultivars. Therefore, the vesicles were at least composed of L-1 and subepidermal inner L-2 cells. This determination of interspecific chimeral construction (which was made possible by molecular techniques) is a valuable finding, in terms of improving Citrus through intentional use of periclinal chimerism. Title: Arising of the intermediated forms by grafting subfamily Aurantioideae. Author, Editor, Inventor: Kapanadze-I-S {a}; Kapanadze-B-I Source: Doklady-Akademii-Nauk. Sept., 1997; 356 (2) 278-279. Language: Russian; Non-English Major Concepts: Horticulture- (Agriculture-) Super Taxa: Rutaceae-: Dicotyledones-, Angiospermae-, Spermatophyta-, Plantae- Organisms: Atalantia-monophylla (Rutaceae-): fruit-crop; Citrus-unshiu (Rutaceae-): fruit-crop; Eremocitrus-glauca (Rutaceae-): fruit-crop; Fortunella-japonica (Rutaceae-): fruit-crop; Microcitrus-excelsa (Rutaceae-): fruit-crop; Poncirus-ichangensis (Rutaceae-): fruit-crop; Poncirus-trifoliata (Rutaceae-): fruit-crop Taxa Notes: Angiosperms-; Dicots-; Plants-; Spermatophytes-; Vascular-Plants Parts, Structures and Systems of Organisms: phloem-; xylem- Miscellaneous Descriptors: chimera-type; grafting-; intermediate-Aurantioideae-forms http://www.serendipityrancher.com/citrusfruits.htm: "A curious aspect of citrus plants is provided by the so-called "freaks," first observed in a Florentine garden in 1640. These citrus plants whose leaves, flowers, and fruits have characteristics varying between the orange and the lemon: lemons with orange skins or vice versa, alternate segments of orange or of lemon. They are "chimeras" or graft hybrids in which there is a kind of fusion of the tissues of the two species. [Bianchini, Francesco, Corbetta, Francesco, Pistoia, Marilena, The Complete Book of Fruits and Vegetables, United States Translation: Crown Publishers, New York, 1976; Originally published in Italy as I Frutti della Terra, Arnoldo Mondadori Publisher, Italy, 1973]" http://www.habitas.org.uk/gardenflora/taxa.htm#Graft http://aggie-horticulture.tamu.edu/t...s/chimera.html http://nucleus.cshl.org/worldpac/eng/slinks/s000856.htm It seems that hypotheses of genetic transformation by graft-hybridization reportedly played a role in the Lysenkoism debacle in the USSR. http://www.wayofscience.info/unit3part8.html: "Setting the stage for Lysenko was another curious figure of the time, Michurin. He was a minor landowner, and a fanatic believer in his own cockeyed ideas about agriculture (i.e., he was a classic "crank"). He was convinced that the scientific "establishment" was too closed-minded to listen to his grand and revolutionary ideas. One of these was graft hybridization, which he said was a speedy way of improving fruit crops. This idea says that, for example, if a branch of a good-fruited but temperature-sensitive apple is grafted onto a poor-fruited but hardy rootstock tree, the seeds produced by the branch will somehow inherit the hardiness from the rootstock. This situation is analogous to saying that a Chinese person getting a kidney transplant from a black African will give rise to dark-skinned children. With what you already know about DNA and genes, it should be clear that the branch (or person) will produce offspring genetically unaffected by the graft. Michurin claimed to have overwhelming evidence for graft hybridization, and impoverished himself privately publishing his great works (since the "establishment" would not). Unfortunately, it was quite apparent to the "establishment" that Michurin had no idea how to do properly controlled experiments. Michurin set the stage for Lysenko, but the two differed greatly. Michurin was a crank, a true believer. Lysenko was a charlatan, a power-hungry anti-intellectual fraud." http://www.comms.dcu.ie/sheehanh/lysenko.htm http://www.human-nature.com/rmyoung/papers/getting.html Darwin also had some comments on "graft hybrids": http://pages.britishlibrary.net/char...riation11.html I get the impression that the whole "graft hybrids" hypothesis reflected vague, pre-modern-genetics notions of heritability, and were supplanted by the "graft-chimera" explanation. cheers |
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