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ISSNOOOI-6799 Acta Phytotax. Geobot. 43 (2): 135-137 (1992)

Chromosomesof Tuxtla pittieri (Asteraceae; Heliantheae)

KAZUO OGINUMA*, GUILLERMO IBARRA-MANRfQUEZ**,

AND HIROSHI TOBE***

'Codege 'tEstacitin of Child Deveiqpment Kbchi PVbmenir Uhiversity, Ohara-cho, Kbchi 78dr de Biotogia 7}'opicalLos Tzaxtts instituto de Bilogit(, UlriiversidbdIVIxcionalAut6noma de Man'co, Apartado Postal 94 San Andres TtLxtleq Vleratcru4 MtExico; '"'IFticulty ofintqgrated Htzman Studias, Kyoto Uhiversity, Kyoto 60cFOI

Abstract 7letxtlapittieri (Asteraceae; Heliantheae), which was reeently described as the only species of a new genus from Costa Rica and Mexico, is found to have 2n=34 (x= 17) and interphase nucleus of difftJse-complex chromocenter type. Of 34 metaphase chromosomes, 30 have centromeres at median position, two at submedian position, and two at terminal-subterrninal position. Shared basic chromosome number x=17 suggests close relationships of Tttxtla to P2irbesina. (Rcceived August 28, 1992; Accepted October 8, 1992)

Key words:Asteraceae, Chromosome, Compositae,7leixtla.

Tttxtla pittieri is a woody liana of Asteraceae (Compositae) and was recently described by Villasenor and Strother (1989) as the only species of a new genus from Costa Rica and southern Veracruz of Mexico. Villasenor and Strother (1989) made intensive and extensive observations on its vegetative and reproductive morphology, and, on the basis of phenetic analyses using 129 characters, suggest a distant relationship of 7le{xtla to any of other possibly related genera Otopmppus, SaLmea, Vkrbayina, and Zexmenia. The present paper reports on chromosome number and morphology of 7letxtla pittieri that is not known yet, and discusses similarities and dissimilarities in chfornosome features between 7}txtla and the other genera.

Materials and Methods

Cytological materials of 7leixdo pittieri (Greeman in W.W. Jones) Villasenor and Strother was collected at Estaci6n de Biologia, Universidad Nacional Autonoma de Mexico, Los Tuxtlas, Veracruz, Mexico (voucher: 7bbe et al., 228 (KYO)). Somatic chromesomes were examined using meristematic cells of young leaves. Pieces of young leaves were collected with forceps from shoot tips, and pre-treated with O.O02M 8-hydroxyquinoline for 4-6 hours at about 20C. They were fixed with a mixture of 99% ethanol, chloroform, and glacial acetic acid (2:1:1) and kept in a refrigerator (at 4-10C) for over 24 hours. Fixed materials were stained and macerated with a 1O:1 mixture of 2% a ¢ eto-orcein and IN HCI for 10L20 minutes at room temperature, and were squashed on glass slides.

Results and Discussion

The interphasenucleus has many dark-stained condensed blocks many chromomeric granules; the condensed blocks are ellipsoidal and irregular inandshape and

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･II･ ge'I :1･}1･ lillgii mt#':iliill SIrki'i･s ' lieil.Ii i Iss i$,Il"ii ii, pt.,,li li

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Figs. 1-4. Somatic chromosomes of 7hrtlapittieri (2n= 34). 1. Interphase, 2. Prophase. 3and4. Metaphase. Scale=2"m.

uniformly distributed in the nucleus (Fig. 1). Such an interphase nucleus is referable to the diffuse-complex chromocenter type (for typification see Tanaka, 1971, 1980). Chromosomes at rnitotic prophase are evenly and slightly stained dark, and do not have the early or late condensed segments (Fig. 2). Chromosomes at mitotic metaphase are 2n = 34, and thus the basic chromosome number of Tuxtla is x=17. The variation in chromosome length is gradual; the longest chromosomes are about 1.7 "m, and the shortest about 1.2 um. Of 34 chromosomes, 30 have centromeres at median position, two at submedian position, and the remaining two at terminal-subterminal position (Figs. 3,4). Based on our review, among the four genera which were discussed by Villasenor and Strother (1989) as possible allies of 7-bextla, Otopappus has x:=r16, Salmea probably x=16, "Chromosome and Vlerbesina x= 17 (for detailed information see the book titled numbers of "Index flowering plants" and serial publications titled to plant chromosome numbers"). On Zexmenia, comprising two species Z. serrata and Z. virgata (Strother, 1991), there is no chromosome information available. Therefore, evidence available indicates that 7'letxtla agrees with Verbesina in sharing x=17, and suggests their mutual relationships. This may further corroborate an arrangement of those genera in a diagnostic key of a subtribe Ecliptinae of the tribe Heliantheae (Strother, 1991), where TtLxtla and Verbesina bifurcately terminate and are positioned next to each other.

The study was supported by funds from Itoh Science Foundation and Yamada Science from Foundation, and in part by a Grant-in-Aid (No. 03640591) for Scientific Research Ministry of Education, Science arid Culture, Japan. We are gratefu1 to Dr. John L, Strother for his guidance of a circumscription of Zexmenia.

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References

ed ． Engl 三sh edition l974 0tto Chromosome Numbers of Flowering Plants．A ．A 。Fedorov （ ）， published in ， Koeltz， Koenigstein． − 1972 R ．」． Moore ed ． 1973 Index to PlantChromosome Numbers．Volumos fGr1967 1971and （ ， ）publishedin ’ 1974 00sthoek s UitgesveTsmaatsschappij B ． V ． Utrecht；volume for l973／1974 （R J． Moore ， ed ．） ald ， ， − − − Utrecht；volumcs f6r 1975 1978 19791981 ， 1982 1983， publishedin l977，Bohn ，Scheltema ＆ Holkema ， ， − − and − in l981 1984 1985 1988， 1990， 1986 1987 and 1988 1989 ．Goldblatt， ed ． ， ， ， 1984 1985， ， （p ）published Garden ． l991，respectively ， MissouriBotanical Strothor， J． L ． 正991． Taxollonly of Compt の ta ， Elaphandra ， Iogeton，ノ匂勉σ， JVamalchitamia， Medelia， 一 − Hll Zexmenia ， a 皿 d Z ソO ，xia （Compositae 且 eliantheae Ecliptinae）． Syst． Bot ． MonogL 33： ． − Tanaka ， R ．1971． Types of resting nuclei i110rchidaceae． Bot ． Mag ． Tokyo 84：118 122． − ，1980，The karyotypc． ln H ． KIHARA （ed ．）， Plant Genetics I． pp335 358． Shokabo Book Co ．， Tokyo （In Japanese）． and for Zexmenia Compositae： Villasenor，J，L ， J．L ．Strother．1989． TtLxtta， a new genus pittieri（ − Heliantheae）． Syst． Bot ．14：529 540．

摘 要

＊ ＊ ＊ ＊ 一 ＊ ・ バ ーマ ン ス ＊ ・ ： Tuxtla （キ ク科 メ ナ 荻沼 男 ギ レ ル モ ， イ ラ リケ 戸部 博 pittieri モ ミ連 ）の 染色体 一 ・ コ 最近 コ ス タ リ カ と メ キ シ か ら の 新属 と し て 発 表 され た Tuxtla の 唯 の 種 T ． pittieri（Greeman in W ．W ． Jones）Villasenor a皿 d Strotherに つ い て ，染色 体数 と核型 が初

“ ” ＝ ＝ で 伽 se −complex め て 明 か に され た 。 染色体数 は 2n 34 （x 17） ，間期核 は di type

の に は 次 か ら で あ っ た 。 34本 の 染色 体 うち ，30本 は 中部に ， 2 本 は 次中部 ， 残 り 2 本 端部 一 ＝ Verbesina つ x 17 が こ と か ， が 端部 に 動原体 を 持 。 染色 体基 本 数 （ ） 致 す る ら Tuxtla で こ が た と近縁 あ る と 示 唆 され 。

＊ ＊ （＊ 〒780 高 知 市 大 原 町 132 高知女 子 大学 保育短期 大学部 ， メ キ シ コ 国立 自治大学生 物学 研究所 ， ＊＊ ＊〒 606 京都市 左京 区 京都大学総合人 間学部 自然 環境学 科）

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