Propagation of Casuarina equisetifolia through axillary buds of ...

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I'lanl Cell Reports (1986) 3: 161-164
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Propagation of Casuarina equiset$bZia through axillaiy buds
of immature feniale inflorescences cultured in vitro
Plant Cell
Re~orts
0 Sprin$x-Verlag 1986
E. Dulioiix I, B. Soiigoufhra *, and Y. Doiiiincrgues
c
IXpartcnient Je Iliologie Vi.gi-tale. FÎICUI~C des Sciences, Dakar, SCii6g:iI
* I-aboratoire de Microbiobgie des sols, ORSTOM, Dakar, Senégal
' I~SS~(CT~/ORSTOM/CNRS), 45 bis Avenue dc la Belle Gabrielle, F-94736 Nogeni-sur-Marne Cedex, Frnnce
I

I62
1965) 30 g 1-1 sucrose, 0.05 pol 1-1 NAA, different
amounts OF BAP ranging from O to 17.2 Irmo1 I-' (~ahIe
l) and 8 ma l-' Ilifco Bacto agar.
i
.
Fig. 1
Tmmatiire remale iiirlorescence (IFI) of
I"isc~orinn cqi/isctifoliti used as explant.
A, ovoid apex with floret meristems ; P,
penduncle (I3ar = 1 mm).
/I f7JCdillnJ for S/lOOt f'~OfJf/ilti~lfl : Same as A
mediiim but with 20 g 1-1 activated charcoal (Merck
21Hh).
f medinm for rlii7oqor~csis : same as A medium
hut without BAP or activated charcoal; we compared
the following concentrations of NAA : 0.05, 0.15,
0.25, 0.5, 1 limo1 1-1 (Table 2).
All three media were adjusted to pH 5.5 before
autoclaving at 1 lOoc for '10 min.
Followine sterilization IFI were aseptically
placed in 10 cm petri dishes (10 IF1 per d'ish) con-
. taining 20 ml of A medium. After 4 weeks IF1 were
transferred into 23 x 15 nui tubes (one IF1 per tube)
containing 25 ml of ß medium.
Kine weeks later the elongated shoots origin:iting
from the axillary buds formed in A medium and
devclopped in I) nicdium were exciscd thus giving microcuttings,
The microciittinp were placed vertically
in 23 x I5 mm tuh1.s (one per trilie) contai.ning 15
ilil cif C medium.
All types of culLtrrrs were incohnted in a j:rowth
chamher at 2811 OC with il 17 11 pliotoperiocl (4,000
tux).
Res u1 t s
\;lien plac:rcf in A nictliilni, lF1 cxliihitctl the fol-
Lowing transformations. After 2 weeks the ovoid head
fnrmed a vegetative axis while the hasal cylindrical
I'eduncle swelled. Later, i.e. after 4 weeks, 5-6
vegetative buds rippearecl at the hase of the IF1
(Fit;. 2).
Fig 2.
Numerous axillary buds formed at the hase
of the TIJI after 4 weeks on A medium (ßar
= 1 m).
Table 1 shows that addition of a cytokinin (BAI')
to the medium containing an auxin (NAA, 0.05 ymol 1-1 )
markedly aEfected bud initiation. The most favornble
medium contained I 1 .1 umol 1-1 BAP and 0.05 )imo1 1-1
NAA. In the experiment reported in Table I we found
that all the 1171 reacted, that is, gave buds, the mean
number of buds being always in the range of 5-6 per
IFI, in the medium with Il .I ymol 1-l BAI'.
D - Sliont elonqation
Five weeks after being transferred onto I3 medium
axillary buds evolved into green, vigorous-lookin!:
5-6 cm long shoots (Fig. 3). However in the absence
of activated charcoal no bud development nor shoot
elongation were observed.
C - Itoot formation
After being excised, shoots obtained in ß niedium
with 1 I .I liin01 1-1 BAP, were used as microcuttings
and placed onto C medium (Table 2).
With 0.5 to I limo1 1-1 NAA, a iew thick. pink,
adventitious rocits wme formed (Fig. 4). We nevbr
observed any callus proliferation at the base of the
microc:uttings.
D - Transplanting anil occl i/notinq
Kooted microcuttings l;rowtl in C medium were
removed from tho test tcihcs after 4 weeks anil transflantcd
from the aj:ar medium into soil in pots plnred
in a greenhouse wider warm and higlily humid c.unditions.
The autotrophic devplopment of the plantlets
was satisfactory, and no bl3giotropic tendency Was
ohserved.
I

(1 n
y "Table 1 Effect of IMP concentration on the mean
nimber of buds originating from each IF1
of rasciorinil eQw'seti folia cultivated on
A medium (0.05 pmol f-l NAA in all media)
-
Concentration Nmber of Number of Mean no of
o f ILI I' repli- reacting buds per
(UllIl)1
-
1-11 cations IF1 IF1
o 47 47 2.59 A0.29
4 .A 49 49 1.53 20.17
8.8 47 47 3.76 i.0.35
11.1 4 7 4 7- 5.78 f0.68
11.2 4 6 46 4.22 i. O .34
--
.
.:!cc771 P~IZ~WU ?SL: in lust column differ
:?':~~:¿fimut%p, P = 0.05 (test or "man
?)I 1 +.'t$icZ.!: iu Sw~leno~ niid Coclrznn, 1973).
163
Fig. 4
Root formation on a microcutting 2 weeks
after placerlient onto C medium (Bar = 1 nun)
Discussi on and Conclusion
FiK. 3 Elongated shoots originating from
axillary buds 5 weeks after transfer
to I\ medium (llar = I mm).
l'able 2
Krfect of NAA concentration on root-.ig of
microcuttings 2-4 weeks after placement
onto C medium (no HAP added).
Conceutration ?lumber of Number of Hean no of
ur N:\h replicates rooted mi- roots per mi-
(lllllU 1 1 -1)
-
crocuttings crocuttings
0.0; 40 O O
0.15 50 0 O
0.2; 47 0 O
0.5 43 14 2
I .u 83 31 2
The ability to vegctacively propagate trees is
associated witli ,jiivc:nility (1;r;iiiclet 1979 ; Franclet
cl: al I9I10). Siilcc it is recognized tliat some parts
of the trees inny be inntiire or senescent while other
portions still display ,juvcniIe characteristics (Hunga
a~id I1urz:in lY82), i t (:tin Irc Itypothesiz.ed that csplants
witli this desi rabic cliLiracteristic should be
more easily pi-op:i#nted. Assuming tliat IF1 of C. equisctifnlio
exhibit this property, we initiated the
investigations whose results ilre reported here. The
success of oiir experiments indicate that IF1 of C.
rqui.sc*tifol ia (niid prol);ibl y also of other Casuarinacen)
constitiite satis€actory explants when dealing
with mature trees. Tnterestingly enough it has been
shown that the period of time during which mature
trees bear TVT could be drtiin;itic:ally exnended, just
by irriyati.ny the nlants.
Tn 'the

..._
164
medium. The beneficial effect of such an addition is
not yet clear and several hypotheses to explain it
have been proposed (Hission et al 1983; Bonga and
Durzan 1982).
The method of micropropagation of C. equisetifolia
based on the use of explants consisting of IF1
that is presented here is easy to handle and could
probably be adopted on a large scale when the rooting
of the shoots is improved. Investigations are
under way to improve the shoot branching and the
development of the root system of the microcuttings,
to find out the most appropriate stage for excising
IF1 from the trees and to check the nodulating ability
of the plantlets when transplanted to pots.
So far, the type of explant used here formicropropagation
of Casuarina equiseti folia has never
been experimented except by Bonga (1984). However,
if this author obtained the formation of adventitious
shoots in cultures of sections of immature cones of
Iarix decidua, he did not observe rooring in any of
the shoots.
Acknowledgement
The work reported here was supported in part by
the International Development Research Center (IDRC)
and in part be CEE research grant 1 SD-081 F.
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