CHROMOSOME NUMBER AND MEIOSIS IN SCLERORHACHIS RECHTNGERI (COMPOSTTAE) S. M. Ghaffari Ghaffari, S.M. 7984L210: Chromosome number and meiosis in Sclerorhachis rechingeri (Compoitae).- Iran. journ. Bot. 2(2): 155-158. Tehran. The chromosomic studies on the species of Sclerorhachis rech- ingeri Iranshahr (2n=18) which is endemic to the north-eastern part of Iran has been caried out and the results are presented. Seyyed Mahmood Ghaffari, Institute of Biochemistry and Biop- hysic, Uniuersity of Tehran, P.O.Box 31-1700, Tehran, Iran. Sclerorhachis rechingeri (Compositae) a:tS ,tr )9,"_e sessrtf re g;rt . .19* t,, * ',l Sclerorhachis rechingeri Iranshahr o;95 orl-.rs tgily:f -UtL (,. ss 5*"o19,-oT6-t::9 o.u pt+;l .-t crlrl d-p Jk 6rt-l a;rS aS 156 S" M. Ghaffari IRAN. JOURN. BOT.2(2), 7984 Introduction The author in a expedition to the pro- vince Khorasan, Iran in late spring 1978 for collecting plant specimens and cyto- logical material came across to a plant species which later identified as Sclero- rhachis rechingeri Iranshahr. This species in fact described and published by M. Iranshahr (1979) after my collection.The exact location where plant material for the cytogenetic and chromosome study of this species was collected is: Province Khorasan, 10 km S. of Robat-e Sefid (Sarcheshmeh Telecommunication Sta- tion), between Mashhad and Torbat-e Heydarieh. Three other species of this genus have so far been known, these includes: S. polysphaera Rech.f. which is endemic to central Afghanistan, S. caulescens (Ai- tch.& Hems.) Rech.f. which is endemic to western Afghanistan and S. Ieptoclada Rech.f. which is the latest species of the genus described from southem Khorasan. S, rechingeri is quite distinguishable from the three other species of the genus by its larger capitula i.e. L2-2O mm in di- ameter versus 5-L0 mm in the other Species. Materials and methods Fig. 7. Sclerorhachis rechingeri(woolly Immature capitula were collected and collar indicated by arrow), x 0.4 IRAN. JOURN. BOT.2(2), 1e84 Meiosis in Sclerorhachis rechingeri 157 immediately fixed in the field in the pb- During anaphase I, phenomen heterozy- nnar,s fixing fluid (ethanol 95Vo: chlor- gous for a paracentric inversion were oform: propionic acid, 6:3:1 V/V). observed.The inversion produces at anap- Floret buds were squashed and stained hase I and pachytene dicentric chrom- with Fe-acetocarmine (Estilai & Ghaffari atid bridges,acentric fragments and loops. 1978). Chromosomes counts were carried out from the meiotic microsporocytes which were prepared as mentioned above. AII References slides were made permanent by the ven- Estilai, A. & Ghaffad, S.M. 1.978: A etian turpentine (Wilson 1945). Photo cytogenetic study of Compositae of graphs were taken from permanent pre- han, I. species of Khorasan provi- parations using a Wild photomicroscope. nce.- 7th. National Genetics Cong- ress. Jundishapur University, Ahvaz, Results and discussion Iran. Meiosis in this species was shown to be Iranshatrr, M. 1979: Sclerorhachis rech- regular forming nine bivalents at first ingeri ( -Asteraceae-Anthemideae ), A metaphase. There was usually one chi- new species from N. Khorasan.- Pl. asma per arm in diakinensis stage and Syst. Evol. L32: L49-152. these were terminally located, thus pro- Wilson, G.B. 1945: The venetian turp- ducing rod sharped or ring bivalents.The entine mounting medium, Stain Tech- latter were formed with grater frequency. nology 20: 133-135. Fig. 2. Photomicrographs of meiotic divisions in Sclerorhachis rechingeri, n=9. - A, B. Pachytene showing loops. - C, D. Diplotene showing interstitial chiasma. - E. Diakinensis showing nine bivalents (3 rods & 6 rings). - F. Metaphase I. - G. Anaphase I showing a single chromatid bridge (arrow). - H. Remains of bridge in- dicated by protrusions form each telophase I group of chromosomes (arrows); acen- tric fragment in near centre area (arrow). - I. Metaphase II. - J. Late anaphase II. - K. Telophase II. - L. Tetrad. 158 IRAN. JOURN. BOT.2(2), l-984 "*l * ,-^ t t J.