Embryology of primula algida and Primula amoena (Primulaceae)

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L335/*"733Q‘"ib-6OU€0O6vL?5bU7.) r)dM‘9{J8(iOl; amaaba, 157, N:l_, 1998

HI 7l.l.l ()l’ Tllli (il-IORGIAN ACADEMY OF SCll5NCI7.S, I57, M1, 1998 M





H-0TAN.Y
M. Akhalkatsi, G. Gvaladie, N. Taralashrili

Embryology of Prinzula algida and Primula amoena
(Primu/aceae) - ‘

|’re'<i,'iilei.l l\\ Con. .‘.leiiiher oiithe ‘Academy (_i T\'akJiuLsrisliVili-May I997
-. ABSTRACT. The ilcrclnprnent of omle and seed is described in’ two species -
Primulu ulgirlrl and I? umm-ml. '
Key words: EMBRYOSAC, FERTlLlZATl0N, EMBRYO. ENDOSPERM:

The earlier investigations on the embryology of Primulacuae [l-5| have been re-
vicned by T. B. Matnetieva [6]. The general -reproductive traits of genus Primula have
been discussed in these publications. However. this information is based on data obtained

,on only 9 investigated species from SOQ species of l’r‘miu/a distributed vVl(‘)fidWldC |7]_,

Only one species - I’. buyer/1ii distributed in Georgia have been studied so far [X.‘)].
In this repon the dcvelopineiit of onilc from time of forination tip to establislunent of"

the mature seed is described in two species '- I’riImII4i a/gala Adam. and R rmmeml Bieb. ‘

The material was collected from the plants growing in the Central Caucasus. Ka/bcgi
region. near church Sameba. The flowers and fniit_s at dilTercnt stages b1'dcvclopineut
were fixed in formalin. glacial acetic acid. 70"; alcohol (5:5:9t)). The permanent prepa-
rations were made according to _l\’amelina ct al. [Hi]. The ob'sen‘ations _were taken on
microscope "Pol_u'ar" (Austria. Reichert). ‘ - -

The mules and seeds of investigated species reveal great siriiilzirity in stnicture.bu1
specific peculiarities of some species were ob_ser\’ed. ' . . -

The following embr} plogicicliaractcrs are general for I’. nlgirla and I’. amuelm. The
oyule is bilcgmic and tcnuinucellate. The outer integnment isthree laycred consistiiig of

. two epidermal layers and one middle la_\cr of small parcncli}matous cells. The_inuer

integnnient possesses outermost later of epidermal cells. middle-5-ti layers 07

parcnchimatous cells and innermost liner \\lIlCll I5 dc\;e'loped into iiitegtiiiieiitziry MP9‘

tum, Micropyle is formed by both integuinents. The mieellus isrepreseitied-l>_\' one layer
of cells surrounding the embryo sac at the time oi itsloriiiation. Ho\\e\'er. during the
maturation the enlarging embryo sac presses the iiticcllar cells and tl1e)":1r.6 d°B°'l°f3‘°d-
In tlic_ mature ovule the inicellus is complete!) absent and embr_\o sac direct_ly_adj0lfl5t 30
the ititegnmcntar_\‘ tapetuni. ‘ _ « '

Only one arcliesporial cell is present in the mules of I’. ulg/“du and I’. amaena. lt

functionsilirectly as inegaspore mother cell and.foi'ms linear telrad. The chala/al nic-

gaspore gives rise to the embryo sac of I’t:lyg<>nIIIr1 type. The itcwly formed cmbryb 54"?

i . (Fig. l. a) contains three celled egg apparatus, central cell with_two polar nuclei and three

antipodal cells. In the‘ mature embryo sac egg cell shows a similar organiratioii charac-
terized for most of angiosperm species. The niicropylar part of the egg cell is occupied b)’

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l‘:llllVf_\:0i()g_V‘ of Primnlu algirla and I’rimuIa (IIII()€N(l (I7:-nriitlan-ac) 9"



_' I a single large vacuole. The
niicletis is situnted in the cltnln/nl
\\ end contnining most of the cyto-

plasm (Fig.1. b). The s_sner-gids




‘R



in most cases reveal typical for

1 nucletis and C_\I0pl:lSlll in tlte
8 £ microp_\Ie part. a mcuole locnted
l
k
t’
‘y

..I/' \
4.,“ Z,s..1 “"-4

in chziln/..'tl end and ti ftltfonn
nppnrutus rndintnig out front tlte
point of ztttncluueitt (Fig l. b).

(D

'9 polari/zttion u ith iuicropt le \ neu-
g ole andtcentrnl situated nucleus
:2) O uere obsened They .'Il‘C consid-
7:7 ' /. ered nsegg cell like s_\nergids.
9,3 /' Anttpodnl cells tire CphClllCl¢’ll
K /r After they are .degeuer.ttcd. clin-
V ‘/ In/ztl part ofthe centrnl cell grons
f t considerably to form an hausto-

» E
Fig. I. a-the newly formed enilvnu are of I’.uIgulat h-the egg
apparatus iit I’. qlgidu, e-the ntnlear ertdnsperrn in Pamoena. d~
f-two-. three and four celled preenihry-v in I'amné/ya

rinl elongation tounrds tlte cha-
lnza and funiculus. The polar
V _ _ nuclei don‘t fuse before fertiliza-
tion. They nr'e located near the egg nppnrattus.

Fertilization is porognntotts. Pollen tn'.e passes through tlte llllCl’0p_\ lo and enters the
embr_\o s;te'\1'n one ofthe synergids which IS degenerated. The second s_\ nergid reuunns
invariuhle untill the first division ofzygote. After the fortnntioti ofproembtjo it is gradu-
ally clegeiiernted. Double fertilization occurs. Fusion between the egg cell nucleus nnd one
oftlte mule nuclei takes place after the fusion in the central cell. Tito t_\ pes oftriple fusion
were obsenfed. In one case. mo polztr nuclei fuse prexiously and the secondnry nucleus
fuses with one of the male pronuclei. ln the other case the male nucleus fuses uith
nticropylc polar nucleus and aifterunrds the fusion of resulting diploid nucleus with ch.t-
la/.nl hnploid polar nucleus occurs. The pl'lll1:lf_\’Cl1d0SpCfll1 nucleus starts to di\ isle before

divisions of endospemi nuclei are nsynchronous. lit the cellular endospernt the outer ln_\ er
is developed into,epide'rmis like stntcture. The eliztlzizul part of the endosperm fomis
haustoriul oiitgroutltes uhich penetrate ovule tissues and result their degeneration nnd
further utili/gttion. Enibtyogeny confortns to (‘m;i*np/u‘//ad type-(Fig. l. d—D. The in.-nnre
seed consists of torpedo stnge Cll1bl')'0, cellular endosperni and seed cont representing one
outer layer of cells with tliickertedeell walls and inner thin tnetnbrnueous envelope formed
from remnants of crushed integtnnentary cells. .

Some species specific" peculiarities different for 1’. algida and Ramoena were ob-
served. In R algida the ovule is anatropous. However, the typical anatropous form of mule



angibspettms polztrimtion with a ’

But. in some suiergitls rexersed '

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tala.4h,\'ili ' '> . ' i
is observed from time when female gainetophyte has reached the fourth nucleate stage (in
- autumn) up to l'ertih/.at'ion. The seed enlarges coiisiderably in width soon after the fertili-
zation and gets irregularly swollen shape. The funiculns of P" nlgizln is 3-4 lavered on
longitudinal ‘section and I8-20 layered on tangential section. In I’. unmwia the ovule
reveals hemianatropous shape, The short ronn_d funiculus consists of,8-‘) layers of cells
’ ’ connecting placenta with chala/.a (Fig. 2). The first
division of zygote occurs after formation of 32-64
endosperm nuclei in I’. .~l/glr/(1, In P (IIm)_ena it
takes place’ after fomiation of 64-128 nuclei in
endosperm. The cell \\ all formation in the nuclear
e_ndosperm stans after only I46 endosperni nticlei
are forniedin R algizla. ln I’. (lHl()e‘_I1(7lhi§p|‘occs§
begins after formation hundreds of endosperm
nuclei. ln I’. anmcna endospernrdevelops except
of chalazal haustoriuni several lateral haustoria
_ penetrating adjacent cells of integumentary tape-
- tum (Fig. l'. c). The haustorial outgrouthes curve aroundthe cells of 'mtegtnuentar_\ tape-
tum. destroy. them and utili/e their remnants. Pol) cnibriony phenomena were observed in
I’. gmoena. The additional einbr_\o arises from egg cell like 5) nergid. The entrance of
additional pollen tube in s_vne_rgid or other signs of fertilization were not observed. This
phenomenon would be considered as apogainy. « ’- ' i



lag. 2. l‘uniculus wiuieelimi th pl enla in
I ‘ umnenu.



The data show that some variable characters such as onile shape._ iitue course of ‘.
zygote and endospertn development. character of haustorial localization in endosperm '

and polyernbriony phenomena could be considered as species specific peculiarities for
'Prm_mIa. In our opinion these phenomena may be associated with reprodu'etive behaviour
of concrete species resulting'in more effective sexual propagation of individuals in defi-
- nite habitat they are distributed. ' - ' t ' . - '
The research ‘described in this publication was possible in part by Grant Nl3.3 from
the Georgian Academy of Sciences. - '

i\'.Ke'tskhu\'eli Institute of Botany
Georgian Aeadein) of Sciences

Rt3i‘r.i:t‘x'<'i;s

l. ll’ Ilofmetrrer. Jahrh. Wiss But . I, llll-W3.

2' I. Seall. Proc. min. Soc. London. 3. ism. 7x.t2t;

3 I\'. .\'t(’7rflnI(l7l)‘llI7t..l. L. .Vur‘ay:Iru. l'h__\1\Ilnt‘l‘l‘iIUl<Vg\’ Ill. l. I963. lU_5'-l_l3. . _

4. It" ll.’ Kagramrmrwa. 'l':»'it(Iein|n‘mlog. I5\luZd0\'1|tllC mstcnij llory .»\7erh.1i_dz_liana. Dflktl. 1372» 3232 (R“55"“)"
3. .4.J.RIcl1ardv. H13’. lhralnm. .’\'evt l’li_\1o|oi_:i<t. 90. 2. I982. 305-.ll4. V - "

6. 7'. I3. Il1qmeIreva.'§r:I\1iitelnay:t emhrinl-ygiva t.wetkn\‘\'lxh ra.~1enit. l ~‘""‘1§”'d- 1.983‘ 24l'243(Russ'm)‘

7. Y J. Na\'t'r. Willdennwia. 15, 2. l‘)X|'v. 475-4X3. - g ’ ' -
X. ill. I. (iar:hechnIazl:e. Bot. XII (St. I‘L"terhun_;). 78, I993. 93-96 (Russian). . ‘

9,1,4 }(9;m[,h,d;g_ 73; ‘\],kg[(;d:g.I‘antxu/Illa. M. GacheclnlatI:e, Z. Gamtiemlulze. K. Zhgerm. 1297. (in P'°’~°)-

ll). 0.-R Kamclina, D. B. I‘ro.i~l'nrina, IV. /1. Zmkma. Bot. '/.h. (St. Peterhurgh 77, 4, I992. 93-96 (“ll-“li‘")-"