Breeding systems of two endemic rainforest species in Southern Chile: Amomyrtus meli (Phil.) Legr. et Kaus. (Myrtaceae) and Luzuriaga polyphylla (Hook.) Macbr. (Philesiaceae)

7 Pages·1999·2.2 MB·English

by  Mary T Kalin Arroyo

CayanaBol.56(1);31-37, 1999 ISSN 0016-5301
BREEDING SYSTEMS OFTWO ENDEMIC RAINFOREST SPECIES IN
SOUTHERN CHILE:AMOMYRTUSMELI(PHIL.) LEGR. ET KAUS.
(MYRTACEAE) ANDLUZURIAGA POLYPHYLLA (HOOK.) MACBR.
(PHILESIACEAE)
SISTEMA REPRODUCTIVODEDOSESPECIESENDÉMICASDEL
BOSQUELLUVIOSODELSURDECHILE: AMOMYRTUS MELI (PHIL.)
LEGR. ETKAUS. (MYRTACEAE) KLUZURIAGA POLYPHYLLA (HOOK.)
MACBR. (PHILESIACEAE)
MaryT. KalinArroyo* & AnaMaríaHumana*
ABSTRACT RESUMEN
Experimental handself-andcross-pollinations, sponta- Se dan a conocer los resultados de pruebas de
neous selfing triáis and emasculation tests to detect autopolinización manual,polinizacióncruzadamanual,
compatibilitystatus,selfingcapacityandagamospermy, autopolinización automáticay emasculación, parala
along with natural fruiting levéis were undertaken in detección del tipo de compatibilidad, autogamia y
the rainforests ofChiloé, 42°S onAmomyrtusmeli agamospermiaenAmomynusmeli(Myrtaceae).especie
(Myrtaceae), endemic to Chile and belonging to a delbosquelluvioso,endémicadeChile,ypertenecienteal
genusendemic totempérate southem South America, génerosudamericanoaustralendémico,yenLuzuriaga
andonLiizuriagapolyphylla(Philesiaceae),endemicto polyphylla (Philesiaceae),especieendémicaaChiley
Chile and belongingtoasmall genus ofGondwanan pertenecienteaungénerodedistribuciónGondwanica.
distribution.Amomyrtusmeli is genetically self-com- Amomyrtusmeliesgenéticamenteautocompatible.Lapro-
patible and non-agamospermous. Natural pollination duccióndefrutosmediantelapolinizaciónnaturalesestadís-
fruit set was statistically indistinguishable from hand ticamenteindistinguibledelniveldefructificaciónobtenido
cross-pollination and hand self-poUination fruit set. porpolinizacióncruzadamanualyautopolinizuciónmanual.
Thisisthesecondrecordofgeneticself-compatiblityin El registrodeautocompatibilidadgenéticaenA. meli
Amomyrtus, confirming that theentire genus is self- constituyeel segundodeestesistemadereproducción
compatible. Self-compatibility inAmomyrtuacontrasts paraelgénero,confirmandoquelaautocompatibilidades
with presence ofgenetic self-incompatibility in other característicaanivel genérico. Laautocompatibilidad
generaofMyrtaceae (LumaandMyrceugenia) in the genéticaen el géneroAmomyrtus contrastacon la
températe rainforest ofsouthern South America. presenciade autoincompatibilidadgenéticaen otros
Luzuriagapolyphyllaisstronglyself-incompatibleand génerosdelafamiliaMyrtaceae(LumaandMyrceugenia)
non-agamospermous. Natural pollination fruit set was del bosque lluviosodel surdeSudamérica.Luzuriaga
statisticallyindistinguishable from hand cross-pollina- polyphyllaesaltamenteautoincompatibleynopresenta
tionfruitset,indicatingefficientpollinationintherain agamospermia. Laproducción defrutosmediantela
forestofChiloé. Self-incompatibility in L polyphylla polinizaciónnaturalesestadísticamenteindistinguibleal
constitutes a second report ofthis breeding system niveldefructificaciónobtenidomediantelapolinización
amongSouthAmericanspeciesofthegenus,whereL. manualcruzada,indicandounsistemadepolinizaciónmuy
radicanshas alsobeen reportedas self-incompatible, eficienteenestaespecieenlosbosquesdeChiloé. La
andaddsanotherspeciestothegrowingiistofobligate- presenciadeautoincompatibilidadgenéticaenLpolyphylla
lyoutbredspeciesamongwoodyandsemi-woodyele- constituyeelsegundoregistrodeestesistemaderepro-
mentsintherainforestfloraofsouthemSouthAmerica. ducciónentre lasespecies sudamericanasdel género,
dondeL. radicansfuerecientementedocumentadacomo
Keywords:Amomyrtusmeli.Luzuriagapolyphylla, genéticamenteautoincompatible.Conelpresentetrabajo
Myrtaceae, Philesiaceae. genetic self-compatibility, seagregaotraespeciegenéticamenteincompatibleala
genetic self-incompatibility, endemic speciesofChile, listacrecientedeespeciesexógamasentreloselementos
rainforest.Chile. leñososysemileñososdelosbosqueslluviososdelsurde
Sudamérica.
Palabras claves: Amomyrtus meli. Luzuriaga
Departamento de Biología. Facultad de Ciencias. polyphylla.Myrtaceae,Philesiaceae,autocompatibilidad
UniversidaddeChile.Casilla653,Santiago,Chile.E- genética,autoincompatibilidadgenética,especiesendémi-
mail:[email protected] casdeChile,bosquelluvioso.Chile.
31
CayanaBot.56(1), 1999
INTRODUCTION with large solitary flowers containing small
amounts of néctar and with fleshy fruits.
The question as to whether genetic self- Luzuriagaisasmallmonocotyledonousgenasof
incompatibility is basal to the angiosperms and Gondwanan distribution containing 4 species
or has evolved on several different occasions (Rodríguez & Marticorena, 1987; Arroyo &
within different angiosperm Hneages is still an Leuenberger, 1988; Arroyo et al., 1996).
openone(Welleretal., 1995).Theanswertothis Luzuriagapolyphylla is endemic to Chile where
crucialquestioninangiospermevolutionrequires itoccursfrom0-800melevationinRegionsVIII
better knowledge ofthe distribution of self- to IX (Rodríguez & Marticorena, 1987), being
incompatibilityatthegenericandfamiharlevéis. especially abundant in rainforest on the Coast
Particularlycritical,arestudiesinwoodyspecies, RangefromValdiviasoath.Riverosetal. (1996)
vines and long-lived perennial species where recently reported genetic self-incompatibility in
self-incompatibility tends to be more frequent Luzuriaga radicans based on work in the
(Arroyo&Squeo, 1990aandb;Arroyo&Uslar, Valdivian rainforest, 40°S, Chile. Nothing is
1993). However, because species in these Ufe knownaboutthebreedingsystemofL.parviflora
forms must usually be studied in field popula- (Hook. f.) R. et P. distributed in New Zealand
tions, they tend to garner less attention. In this (Rodríguez&Marticorena, 1987).
paperwe report the results ofexperimental tests
to detect genetic self-incompatibility in
Amomyrtus meli (Phil.) Legr. et Kaus. MATERIALSANDMETHODS
(Myrtaceae) and Liizuriagapolyphylla (Hook.)
Macbr.(Philesiaceae)inhabitingtherainforestsof Tests on Amomyrtus meli were conducted
Chiloé, Chile. In both ofthese two small genera. daringNovember, 1997attheEstaciónBiológica
other species have already been tested for self- Senda Darwin , Chiloé (42°S). Tests on
incompatibility(Riverosetal., 1996). Luzuriagapolyphylla were conducted over the
Amomyrtus meli (Phil.) Legr. et Kaus. is a period October 1997- January 1998 at the same
large rainforest tree to 20 m tall occuning from locality. Here both species occur in perhumid
AraucotoChiloé.ThegenusAmomyrtus(Burret) rainforest zone (AiToyo etal, 1996) along with
Legr. et Kaus, (Myrtaceae), comprising two Podocarpus nubigena, Saxegotliaea conspicua,
species, is endemic to southern South America Weinmcmniatrichosperma,Caldcluviapaniculata,
(Arroyo etai, 1996). Amomyrtus luma (Mol.) Myrceugeniaplanipesand Tepualiastipularisas
Legr. etKaus., the second species, is a shrub or the main tree species. Opaque-white-tlowered
tree occurring in humid forest habitats from Luzuriagapolyphyllagrowsonlivingtrunksabout
MauletoAyseninChile,andNeuquéntoChubut 1-2 m fromground level. Annual precipitation at
in the Andes of Argentina. Both species of Pudeto. located cióse to Senda Darwin is 1.809
Amomyrtus have large white flowers with copi- mm; meanannual temperatureis 11°C (Hajek&
ous pollen, and fleshy black fruits (Landrum, DiCastri, 1975).
1988).FlowersofA. lumaareknowntobevisited Toinvestígatethebreedingsystem,handself-
by Hymenoptera (Halictidae) and Díptera pollinations, hand cross-pollinations, spontaneous
(Syrphidae) (Riveros eta/., 1991). Although the selfing triáis and emasculations without further
ovarles of these species contain numerous pollination were conducted on plants growing in
ovales, matare fruits normally contain 1-3 large the field previously bagged at the flower bud
seeds,4-6mmlong,thesebeinglargerinA. meli. stageinwhiteorgandypollinationbags.Eachtest
Riveros et al. (1996) recently reported the pres- was conducted on several different individuáis
ence genetic self-compatibility in Amomyrtus growing at the same location. Pollinations on
luma based on work in the Valdivian rainforest, Luzuriagapolyphylla were spread over a period
40°S, Chile. It is of special interest, thus, to of 15 days; those onAmomyrtus meli over 20
determine whether self-incompability character- days. Over these same periods, to evalúate the
izesA.meli.Amomyrtusmeli,unliketheA. luma, efficiency ofthe pollination system, additional
isstrictlyendemictoChile. unbagged flowers on both species were marked
Luzuriagapolyphylla (Hook.) Macbr. is a andassessedforfruitsetsoastocomparethelevel
high-climbing semi-woody epiphytic species offruiting undernatural conditions ofpollination
32
Breedingsystemsot'twoendemicrainloicsispccics:Arrovo,M.T.K.&A.M.HUMANA
tothatobtainedunderhandcross-pollination. For than spontaneous self-pollination fruit set (G,^^, =
self-pollination. poUen from the same lloweror 5.415: p<().05). The ISI (measure ofdegree of
from other ñowers on the same individual was self-incompalibilily lluctualingbetweenOand I:O
iised. For cross-pollination, fresh pollen was =full self-inconipalibility: 1 =fullcompatibilily -
collected from individuáis located distant from see Ruiz & Arroyo, 1978) for-4. meli is 0.50,
thetestplant, andtransported immediatelytothe which iswellabovethevaluéof0.2u.sedbycon-
receptivestigmasofbaggedtlowers.Eachflower vention todifferentiate between .self-incompatible
was poliinated on three sepárate occasions so as andself-compatiblespecies(c.f. Arroyo&Squeo,
to increase the likelihood ofencountering the 1990b).Amomyrtusmelithus isclassedas aself-
stigmas at their máximum period ofreceptivity compatible species, although clearly, the level of
and ofobtaining physiologically máxima! fruit compatibilityisonlymodérate.
and seed sets. All poliinations werecairied in the Only3.5%ofthehandself-pollinatedtlowers
earlyaftemoonwhentemperaaireswerewarmerixnd ofLiizuriagu polyphylla produced fruit (Table
thetlowerswerefullyopen. Followingmarking,all II). Inthespontaneouslyselfingtriáis,notlowers
manipuiated tlowers were immediately rebagged. producedfruits, as was thecase foremasculated
CompletefruitmaturationinLitziiríagapolyphylla tlowers (Table II). In contrast, 58.5% ofhand
in Chiloé requires around 8-9 months (Smith- poliinated cross-pollinated flowers produced
Raniírez & Armesto, 1994). Long fruit matura- fruits.aproportion thatismuchhigherthanwith
tion periods have also been described in L. hand self-pollination. These results give an ISI
marginara (Arroyo & Leuenberger, 1988) and valué of0.026, which is well below the cut-off
wouldappeartobecharacteristicofthegenus.In valué of0.2 and allow the conclusión ofa high
order to avoid loss offruits in the experimental levelofgeneticself-incompatibilityinLuzuriaga
crosses andothertestsduetoautumn andwinter polyphylla.
stormdamage,weharvestedfruitsofthisspecies Natural fruitproductioninAmomyrtu.smeli
in late summer as they began to mature. Fruit was modérate (Table III), but not significantly
maturation in Amomyrtiis meli occurs over the different from that in any of the experimental
period December to April (Smith-Ramírez & treatments (G^^. = 1.696: NS: (spontaneous self-
Armesto, 1994). Forourexperiments,fruitswere ing); G^jj = 0.519; NS (hand self-pollination):
harvestedinApril, 1998. Inbothspeciespollina- G^j. = 0.413, NS (hand cross pollination)).
tion bags were retained on the plants until the Thereforethe fruits produced under natural con-
timeoffruitcoUection,soastopreventfruitloss ditions ofpollination in Amomyrtus meli could
through the action ofthe biotic dispersal agents havebeenderivedfromspontaneousintra-flower
(Armesto et al., 1987) and facilítate capture of self-poIUination orgeitonogamy (self-pollination
anymaturefruitsthatpotentiallycouldhavefallen as a result ofpollen transference among tlowers
by the time offruit harvest. Fruits ofLuzwiaga of the same individual) or cross-pollination.
polyphylla tend to fall easily with any distur- Mostly likely natural pollination fruit set is
bance. derivedfromalltypesofpollination.
Natural fruitproduction in unbagged tlowers
ofLuzuriaga polyphylla was surprisingly high
RESULTSANDDISCUSSION (Table IV) for a strongly self-incompatible
species and not significantly different (G^| =
Under hand self-pollination 13.5% ofthe 1.46;NS)fromthatobtainedunderhand-pollina-
flowers ofAmomyrtus meli produced fruits, in tion in which all stigmas were artificially polii-
comparison with 24.3'7f under hand cross-polli- nated, suggesting high efficiency ofthe natural
nation. In the spontaneously selfingtriáis. 10.5% pollination system. Seed number per fruit was
ofthe tested tlowers produced fruits (Table I). somewhat higher in naturally poliinated flowers
Cross-pollinationandself-pollinationfruitsetfor than in hand cross-pollinated tlowers (t (d.f. =
A. meli(Gjj =2.234; NS) were not significantly 80)=5.598:p<0.001)(TableIV).Thislastsitu-
different, as wasthecaseforself-pollination and ation is commonly encountered in field pollina-
spontaneous self-pollination (G^j = 0.269: NS). tiontests(c.f.Arroyo&Squeo, 1990a)where. in
Cross-pollinationfruitsetwassignitlcantlyhigher spite of repeated poliinations. it is difficult to
33
CayanaBot.56(1),1999
assure the exact timing of máximum stigma representaron ofself-incompatibility and other
receptivity. As an aside, it should be noted that outcrossing breeding systems such as dioecism
mature fruits ofL. polyphylla are greenish at among woody species in températe forests in
maturityinChiloé(Aimestoetal,1987).Hoffmarm Chile (Arroyo & Uslar, 1993; Riveros et al.,
(1982) illustrates the fruits ofL. polyphylla as 1995, 1996;Castoretal, 1996)andaddsanother
greenish-yellow. Rodríguez & Marticorena species to the long list of self-incompatible
(1987) describe the fruits ofL. polyphylla as species in southern South American températe
reddish-orange. Evidently more work is needed rainforests. Thepresenceofself-incompatibilityin
to define fruit colours in the South American twoSouthAmericanspeciesofLuzuriagaraisesthe
species ofLuzuriaga. The high level ofgenetic question about the remaining two species ofthe
self-incompatibility demonstrated in Luzuriaga genus,andespeciallyNewZealandL.parviflora.In
polyphyllahighlightsitsdependenceuponextemal view ofthe disjunct distribution ofthe genus in
pollinating agents. Riveros etal. (1991) reported NewZealand and southem SouthAmerica, Infor-
thatflowers ofL. radicans are visited by halictid mationonthebreedingsystemofthelatterspecies
bees in Parque Nacional Puyehue, 40°S, and would be particularly welcome. Interestingly, and
flowers ofL. marginata, aspecies closely related in contrast with what has been demonstrated in
toLpolyphylla(Rodríguez&Marticorena, 1987), the Chilean flora (e.g. Arroyo & Squeo, 1990b;
are reported to be sweetly fragrant (Arroyo & Arroyo&Uslai-, 1993;Riverosetal, 1995, 1996)
Leuenberger, 1988), also suggesting bee pollina- self-incompatibility is known for a very limited
tion. Unfortunately nothing is presently known number of species in the New Zealand flora,
aboutthepollinationbiologyofL.polyphylla. We although as Webb & Kelly (1993) point out, the
failedtoobservepollinatoractivityonLpolyphyl- sample size forNew Zealand is perhaps still too
la while carrying out our crossing experiments. smallforanyconvincingconclusionsatthisstage.
However, causal visits by Bombus dalhbomi to
the very similar flowers of L. radicans were
observed. Bombus dahlbomi is a common large ACKNOWLEDGMENTS
bumblebee in the forests of Chiloé.
Undoubtedly adetailed studyofthepollination Research supportedbyCONICYTGrantN°.
mechanisms ofthe three Chilean species, taking 1950461 and an Endowed Chilean Presidential
their wide latitudinal distributions into account, Science Appointment (CátedraPresidencial de
wouldproveveryinteresting. Ciencias-1997)(MTKA).
The results reported here in conjunction
with earlier work by Riveros et al. (1996) on
Amomyrtus lurna confirm that all extant species LITERATURECITED
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compatibility inAmomyrtus could be indicative Arroyo, M.T. K. & F. Squeo. 1990b. Relationship
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Tablei.Resultsofcontrolledhandpollinations,spontaneousselfmgtriáisandemasculationtestsinAmoinyniismeli
(Myrtaceae)intempératerainforestinChiloé.
CayanaBot.56(1), 1999
TableII. ResultsofcontroUedhandpollinations, spontaneousselfingtriáis andemasculationtests inLiizuriaga
polyphylla(Philesiaceae)intempératerainforestinChiloé.
BreedingsyslemsoftwoL-ndemicrainlbrestspecies;Arkovo,M.T.K.&A.M.HUMANA
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