Báo cáo khoa học: "Rejuvenation of a 100 yr old giant sequoia (Sequoiadendron giganteum Buchholz) through in vitro meristem culture"

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Rejuvenation of a 100 yr old giant sequoia (Sequoiadendron giganteum Buchholz) through in vitro meristem culture O. Monteuuis M.C. Bon France Association For6t Cellulose (AFOCEL), Domaine-de-1’Etan!on, Nangis, 77370 Introduction Experimental methods materials The mature and the juvenile were concurrently compared regarding their respec- Vegetative propagation is currently re- tive capacities for vegetative propagation, using cognized as a powerful tool for forest tree propagation by cuttings, grafting and sub- sequently in vitro methods. These included sub- improvement to increase forest plantation cultures with sequential BAP (benzyla- yield (Zobel and Talbert, 1984). However, minopurine) treatments (Fouret et al., 1986), selected trees - the ortets - must develop micrografting (Monteuuis, 1987a) and meristem enough to reach a sufficient size for culture (Monteuuis, 1987b, 1988). Rejuvenation reliable evaluation of their genetic poten- of the mature material was evaluated through morphological - especially leaf form - and tial, which is accompanied in most cases organogenic capacity criteria, with reference to by a significant decrease of their capaci- known juvenile material. In addition, these ties for cloning by asexual propagation observations were supported by biochemical methods. In this context, the possibilities investigations (Bon, 1988). of cloning selected mature tree genotypes true-to-type remain greatly influenced by the prior rejuvenation of the ortets. This Results problem was investigated at AFOCEL using Sequoiadendron giganteum Buch- holz. Under nursery conditions, the mature material failed to root, while the juvenile clone rooted but rooting ability denoted seasonal variations. Moreover, it was Materials and Methods shown that leaf form may be a reliable marker for rooting (Monteuuis, 1985). The Plant material rejuvenation of the apical meristem of the The mature material originated from a 100 yr scion resulting from grafting onto a young old Sequoiadendron giganteum selected in seedling and expressed through a mor- situ. The easy-to-root juvenile clone used as the phological juvenile type reversion, was control consisted of young cuttings derived from shortlived and did not induce any improve- a 2 yr old seedling.
to be determinant in ment of the rooting ability of the mature draud, 1987) proved material. Similarly, despite using scions as successful meristem culture of ensuring the mature material. Thus, when removing small as 200-300 pm, rejuvenation at- tempts through in vitro micrografting led to the meristems at bud-break, it was pos- sible to regenerate a truly rejuvenated only temporary rejuvenation (Monteuuis, line. The rejuvenated plantlets exhibited 1987a). Nevertheless, the fleeting mor- phological rejuvenation corresponded with the same morphological characteristics the meristem protein pattern associated and organogenic potentialities, including with juvenile material (Bon and Monteuuis, rooting abilities, as the juvenile clone. This rejuvenation has been maintained for 1987). more than 2 yr for in vitro as well as for Subcultures ofmicrocuttings using BAP outdoor cultivated rooted cuttings. In ad- appeared to be less effective treatments dition, the rejuvenated material produced than for other species (Fouret et al., 16 kDa protein found in juvenile a 1985). Morphological and organogenic Sequoiadendron giganteum (Bon, 1988). observations conducted over a 3 yr period showed that in vitro medium macro- nutrients and, more particularly, the phy- siological state of the explant caused Discussion and Conclusion variations even under stable environ- mental conditions (Monteuuis and Bon, 1986; Monteuuis et aL 1987). Taking into giant sequoia, like most forest tree For account this physiological parameter sus- species that do not sprout from stumps, ceptible of fluctuating greatly under out- the only possibility indeed to clone select- door conditions (Monteuuis and Gen- ed mature trees is to rejuvenate them
dimorphism that reflects the juvenility of ramets taken foliar through manipulations degree of its apical meristems, appears to In this context, propaga- from the crown. be a good model for the study of phase tors must be aware of the very promising change phenomena of forest trees. In this potentialities of shoot apical meristems, way, most of the investigation procedures, which may theorically be capable of totipo- and especially biochemical techniques tency (Margara, 1982), although some (Bon, 1988), proven to be powerful analyti- state that irreversible matura- specialists tion processes occur within apical meris- cal tools for giant sequoia, are actually being applied at AFOCEL to other prom- tems of aborescent species in proportion ising forest species in order to enhance to the number of mitotic divisions their their ability for true-to-type cloning. cells undergo (Fortanier and Jonkers, 1976). Our results, based concurrently phy- on siological, biochemical, histocytological, References organogenic and morphological investiga- tions (Bon, 1988; Monteuuis, 1988), sup- Bon M.C. (1988) Aspects biochimiques du clo- port the hypothesis that shoot apical nage de sequoias g6ants jeunes et ages. Ph.D. meristems of trees should be able to Thesis Université Blaise-Pascal, Clermont- Ferrand. France express, according to a reiterative pattern, Bon M.C. & Monteuuis O. (1987) Application de juvenile potentialities during a period that la technique micro 2 D PAGE au microgreffage shortens with increasing ontogenic de- de Sequoiadendron giganteum Buchholz. C.R. velopment, the maximum intensity corre- Acad. Sci. Paris Ser. lll 224, 667-670 sponding to bud-break. This opinion is in Edelin C. (1987) Oral communication ’ta total accordance with Krenke’s (1940) R6it6ration adaptive’: Phenomenes de r6it6ra- tion chez les végétaux ligneux Grenoble, Fran- conception of maturation, although this ce, 24 September 1987 juvenile state remains invisible most of the Fortanier E.J. & Jonkers H. (1976) Juvenility time, probably as a consequence of the and maturity of plants influenced by their onto- inhibitory correlative systems. But it should genetical and physiological ageing. Acta Hor- be noted, as reported by Edelin (1987) tic. 56, 37-44 that, in certain cases, meristems do not Fouret Y., Arnaud Y. & Larrieu C. (1985) Rajeu- nissement in vitro du Sequoia sempervirens. need to be excised from the mature ortet Ann. AFOCEL 1984112-137 in order to develop ontogenetical rever- Fouret Y., Arnaud Y. & Larrieu C. & Miginiac E. sions exhibiting the juvenile traits that (1986) Sequoia sempervirens as an in vitro characterize the first phases of ontogeny. rejuvenation model. New Zealand J. For. Sci. In contrast to the truly rejuvenated 16, 319-327 (1940) The theory of the cycle of Krenke W.P. plants obtained from meristem culture, the rejuvenation of plants and its and senescence ephemeral morphological rejuvenation practical application. Plant Breed. Abstr. 15, 1- induced by micrografting (Monteuuis, 135 1987) could be interpreted as a simple In: Bases de la multiplication Margara J. (1982) and temporary transfer of hypothetical vegetative. INRA, Versailles, France pp. 262 rejuvenating substances from the juvenile Monteuuis O. (1985) La multiplication v6g6ta- tissues of the seedling rootstock to the tive du sequoia g6ant en vue du clonage. Ann. AFOCEL 1984139-171 1 mature scion meristem, rather than self- a Monteuuis O. (1987a) Microgreffage du sequoia juvenile-status functioning. g6ant. Ann. AFOCEL 1986 39-61 As a concluding remark, it should be Monteuuis O. (1987b) In vitro meristem culture added that Sequoiadendron giganteum, of juvenile and mature Sequoiadendron gigan- due to its specific characteristics including teum. Tree Physiol. 3, 265-272
Monteuuis O. (1988) Aspects du clonage de giganteum during rest and growth phases. sequoias g6ants jeunes et ages. Ph.D. Thesis, Tree Physiol. 3, 257-263 Universit6 Blaise-Pascal, Clermont-Ferrand, Monteuuis 0., Bon M.C. & Berthon J.Y. (1987) France Micropropagation aspects of Sequoiadendron Monteuuis O. & Bon M.C. (1986) Microboutur- giganteum juvenile and mature clones. Acta age du sequoia g6ant. Ann. AFOCEL 1985 49- Hortic. 212, 489-197 87 Zobel B. & Talbert J. (1984) In: Applied Forest Monteuuis O. & Gendraud M. (1987) Nucleotide Tree Improvement. John Wiley & Sons; New and nucleic acid status in shoot tips from juve- York, pp. 505 nile and mature clones of Sequoiadendron