The Giemsa C-banded karyotype of Crithopsis delileana (: )

Linde-Laursen, Ib; Frederiksen, Signe; Seberg, Ole

Published in: Hereditas

Publication date: 1999

Document version Publisher's PDF, also known as Version of record

Citation for published version (APA): Linde-Laursen, I., Frederiksen, S., & Seberg, O. (1999). The Giemsa C-banded karyotype of Crithopsis delileana (Poaceae: Triticeae). Hereditas, 130(1), 51-55.

Download date: 29. sep.. 2021 Hereditas 130: 51 -55 (1999)

The Giemsa C-banded karyotype of Cvithopsis delileana (Poaceae; Triticeae) IB LINDE-LAURSEN', SIGNE FREDERIKSEN2 and OLE SEBERG2 Biology and Biogeochemistry Department, Rise National Laboratory, Roskilde, Denmark Botanical Institute, University of Copenhagen, Copenhagen, Denmark

Linde-Laursen, I., Frederiksen, S. and Seberg, 0. 1999. The Giemsa C-banded karyotype of Crithopsis delileunu (Poaceae; Triticeae).-Hereditrrs 130: 51-55. Lund, Sweden. ISSN 0018-0661. Received November 5, 1998. Accepted January 12. 1999

Three populations of Crithopsis delileunu had similar karyotypes. They included 14 large chromosomes; five pairs of metacentrics, one pair of submetacentrics, and one pair of metacentric SAT-chromosomes with rather small satellites. The karyotypes of two populations were investigated in detail through application of Giemsa C-banding, Giemsa N-banding and AgN0,-staining to meta- and interphases. The C-banding patterns included a few small to very small, mainly centromeric or telomeric bands. The chromosomes of the two populations were differentiated by banding pattern polymorphism. Banding patterns identified homologous and discriminated among non-homologous chromosomes within the same population. The scarcity of diagnostic bands prevented identification of homologous chromosomes between populations beyond the level obtained from morphology, i.e., of submetdcentrics and SAT chromosomes. N-banding produced no or few weak bands. Silver nitrate staining produced two NORs and two nucleoli corresponding to the number of SAT-chromosomes. The data give some support to a hypothesis of a closer relationship between the genera Critlzopsis and Tueniutherum, than between either of these and the genera Psuthyrostuchys and .

Ib Linde-Loursen, Botunicul Section, Deportment of Ecology, The Royul Veteririury and Agriculturul Univer.yity, Rolighedsvej 21, DK- 1958 Frederiksberg C (Copenhugen), Dwnnurk Signe Frederiksen and Ole Seberg, Botanical Institute, Uniuersity of Copenhugen, Gothersgude 140, DK- 1123 Copenhugen K, Denmurk

The annual species C. delileanu (SCHULTES) RO- on this basis, to see whether or not the data confer SHEV. is the only member of the Crithopsis added substance to the hypothesised relationships JAUB. et SPACH. (Poaceae; Triticeae). It is dis- with the genera Taeniatherum, Psathyrostuchys and tributed from western Afghanistan and Baluchistan Hordeum as indicated by morphology. We have pre- to (FREDERIKSEN1993). According to viously used the techniques successfully with the Love (1984) it carries the K genome. SAKAMOTOand chromosomes of species of these genera (LINDE- MURAMATSU(1965) were the first to report 2n = 14. LAURSEN198 1, 1984; LINDE-LAURSENand BOTH- This number was confirmed by SAKAMOTO(1973) in MER 1984a,b, 1986; LINDE-LAURSEN and material collected in and by FREDERIKSENFREDERIKSEN 1989; BADEN et al. 1990; LINDE- (1993) in populations from , from the island of LAURSENand BADEN 1994a,b; LINDE-LAURSENet Crete, Greece, and from Palestine. Both authors re- al. 1995). ported that the chromosomes were meta- or submeta- centric. FREDERIKSEN(1993) observed that one pair carried rather short satellites. Traditionally, the MATERIAL AND METHODS diploid genera Crithopsis, Taeniatherum NEVSKI . - Three populations of C. delileanu previ- and Psathyrostachys NEVSKI, and Hordeum L. have ously studied by SAKAMOTO(1 973) and FREDERIK- been considered rather closely related (e.g., BOTHMER SEN (1993) were used (Table 1). For their origins, see et al. 1995), sharing a similar spike morphology (2-3 the latter. Seeds were germinated and plants grown as spikelets per node). Recent phylogenetic analyses described in LINDE-LAURSEN(1975) and LINDE- based on morphology support a close relationship as LAURSENet al. (1980). Only the populations H 5558 all four genera are included within the same, albeit from Iraq and H 5562 from the island of Crete, not fully resolved clade (FREDERIKSENand SEBERG Greece, were studied in greater detail. 1992 and unpubl.). Cytology. - Giemsa C-banding and Giemsa N-band- The aim of the present paper was to characterize ing were performed on meristematic root-tip cells the chromosome complement of C. delileanu in detail following LINDE-LAURSENet al. (1980) and LINDE- through the application of Giemsa C-banding, LAURSENand BOTHMER (1984a), respectively. Silver Giemsa N-banding and silver nitrate staining, and, nitrate staining of somatic metaphases and inter- 52 I. Linde-Laursen et al. Hereditas 130 (1999) phases to demonstrate nucleolus organizer regions some pair (Fig. 1 and 2). The rather small satellites (NORs) and nucleoli, respectively, was done accord- were carried on the subtending short arms of the ing to LINDE-LAURSEN(1984). Most observations of latter pair. Only the two last-mentioned chromosome banding patterns were performed on metaphases pairs could be identified reliably by morphology derived from root-tips of germinating seeds as these within and between populations establishing homol- generally had bands of a higher quality than ogy. The morphological differences between the metaphases from root-tips of plants growing in pots metacentric chromosomes were insufficient for safe in the greenhouse. identification. Idiogrums. - The construction of idiograms followed The C-banding patterns were characterized by the LINDE-LAURSENet al. (1980). The chromosomes as presence of two or three small or very small bands measured in one cell of each population having 14 per chromosome arm, mostly located at centromeric well-spread chromosomes identifiable by their C- and telomeric positions (Fig. 1 and 2). A few bands, banding patterns were grouped into metacentrics, generally located at distal positions were intercalary. submetacentrics and satellited (SAT-) chromosomes Bands were present at both sides of the nucleolar (cf. LEVANet al. 1965). Within the group of metacen- constrictions with the larger ones in the short arms. trics, the chromosomes were arranged by decreasing The banding patterns of populations H 5558 and H length. C-banding patterns were primarily prepared 5562 were polymorphic. Within populations the vari- from observations on 14 well-banded chromosomes ation in banding patterns was sufficient for identify- of four cells collected from two plants of either ing the homologous chromosomes of each of the population. The content of constitutive heterochro- seven pairs and differentiating between non-ho- matin was estimated according to LINDE-LAURSENet mologous chromosomes. Between populations, the al. (1980). scarcity of diagnostic bands coupled with the banding pattern polymorphism prevented a safe identification of chromosome homology beyond the level already RESULTS obtained by observation of the non-banded chromo- somes, i.e., of submetacentric and SAT-chromo- The three accessions of C. delileanu had 2n = 14 somes. The identical banding patterns of the two (Table 1; Fig. 1) in accordance with previous counts homologues of each chromosome pair agrees with the (SAKAMOTOand MURAMATSU1965; SAKAMOTO generally inbreeding reproductive system of the spe- 1973; Frederiksen 1993). The chromosomes were cies (FREDERIKSEN1993). large. The mean lengths of the chromosomes of pop- Giemsa-stained interphase nuclei presented small ulations H 5558 and H 5562 were 10.5 and 13.7 pm, chromocentres in a number corresponding with that respectively (Table I). The difference in mean length of the more conspicuous C-bands. The amount of is due to differences in chromosome contraction as constitutive heterochromatin that ranged from 3.5 to the quotient longest/shortest chromosome of 1.5 is 5.3 per cent of total chromosome length was low in the same (Table 1). Their karyotypes were similar and accordance with the presence of few and small C- corresponded overall with figures of metaphases pub- bands only (Table 1). lished earlier (SAKAMOTO1973; FREDERIKSEN1993). N-banding produced no or few weakly developed They included five pairs of metacentrics, one pair of bands in the chromosomes at the same positions as submetacentrics, and one metacentric SAT-chromo- C-bands.

Table I. Chromosome number, maximum number of submetacentrics, SA T-chromosomes, NORs and nucleoli, mean chromosome length, quotient longest /shortest chromosome, and amount of constitutive heterochromatin (Per cent) oj the Crithopsis delileunu populations studied Pop. No. 2n No. observed (max.) Mean chr. Longest/ Const. het. length (pm)’ shortest chr. chrom. (Yn) Submeta- SAT-chr. NORs Nucleoli centrics

H 5558 14 2 2 2 10.5 (8.7-13.3) 1.5 5.3 H 5562 14 2 2 2 2 13.7 (11.0-16.6) 1.5 3.5 H 5571 14 2 2 2 T. c.-m.’ 14 2 2 2 2 12.8 (9.6-16.8) 1.3 4.6

I Tuenicrtherurn cuput-medusae. Cf. Table 1 in LINDE-LAURSENand FREDERIKSEN (1989). Average of observations in three diploid plants Range in brackets Hereditas 130 (1 999) C-bunded kuryotvpe of Crithopsis delileunu 53

In contrast to the comparatively minor differences in chromosome morphology that distinguish the karyotypes of C. delileunu and T. cuput-medusue, the karyotypes of the members of the genera Psnthy- rostuchys and Hordeum that have been included in a clade together with the species of Crithopsis and Tueniutherum (FREDERIKSENand SEBERG1992, and unpubl.) show some clearly distinguishing and virtu-

Fig. 1. Giemsa C-banded chromosomes of Crithopsis delileuna H 5558, 2n = 14, at somatic metaphase. Bar = 10 Pm.

Silver nitrate staining maximally identified two nu- cleolus organizer regions (NORs) in the shape of two darkly stained regions at the nucleolar constrictions of the SAT-chromosomes (Table 1). The number of NORs was confirmed by observing a maximum of two nucleoli in interphases (Table I). DISCUSSION a The karyotypes of C. delileanu studied in detail were similar. Their C-banding patterns were as expected polymorphic in agreement with their widely separated geographic origins. This polymorphism combined with the shortage of diagnostic bands prevented iden- tification of homology of chromosomes between pop- ulations beyond the level inferred from observations of chromosome morphology, i.e., of submetacentrics and SAT-chromosomes. As the homologous chromo- somes of C. delileunu cannot all be recognized indi- vidually, only general statements about their possible relationships based on similarity can be proposed. The karyotype of C. delileunu with 14 chromosomes consisting of five pairs of metacentrics, one pair of submetacentrics, and one pair of metacentric SAT- chromosomes with fairly small satellites is morpho- logically rather similar to that of T. cuput-medusae (L.) NEVSKI (LINDE-LAURSENand FREDERIKSEN 1989). Other parts of karyotype morphology sets Crithopsis apart from Tueniutherum, for instance, the quotient longest/shortest chromosome is greater in C. delileunu than in T. cuput-medusae. Also the C-band- ing patterns show differences in the distributions of n conspicuous bands with C. delileunu having more telomeric and fewer intercalary bands than T. cuput- Fig. 2 a and b. Idiograms of the chromosomes of Crithopsis delileunu showing positions and relative sizes of C-bands medusae (LINDE-LAURSENand FREDERIKSEN1989; (Broken lines indicate very small, inconsistently observed this study). bands). (a) H 5558; (b) H 5562. 54 I. Linde-Laursen et al. Hereditas 130 (1 999) ally no common characters. Species of Psathy- REFERENCES rostachys have significantly larger chromosomes Baden C, Linde-Laursen I and Dewey DR, (1990). A new comprising SAT-chromosomes with generally Chinese species of Psathyrostachys (Poaceae) with notes minute satellites, than the species of the other three on its karyotype. Nord. J. Bot. 9: 449-460. genera (e.g., LINDE-LAURSENand BOTHMER Bothmer R von, Jacobsen N, Baden C, J~rgensenRB and 1984a,b; LINDE-LAURSENand FREDERIKSEN1989; Linde-Laursen I, (1 995). An ecogeographical study of BADEN et al. 1990; LINDE-LAURSENand BADEN the genus Hordeum. 2nd edn. Systematic and Ecogeo- 1994a,b) and species of Hordeum have chromo- graphical Studies on Crop Genepools 7. IPGRI, Rome. Frederiksen S, (1993). Taxonomic studies in some annual somes that produce bands after N-banding (e.g., genera of the Triticeae (Poaceae). Nord. J. Bot. 13: LINDE-LAURSEN1981; MORRISand GILL 1987; Xu 481 -493. and KASHA 1992), a reaction unobserved in the Frederiksen S and Seberg 0, (1 992). Phylogenetic analysis other genera (LINDE-LAURSENand BOTHMER of the Triticeae (Poaceae). Hereditas 116: 15-19. 1984a,b, 1986; LINDE-LAURSENand FREDERIKSENGill BS, (1987). Chromosome banding methods, standard chromosome band nomenclature, and applications in 1989; BADEN et al. 1990; LINDE-LAURSENand cytogenetic analysis. In: Wheat and Wheat Improve- BADEN1994a,b; this study), signifying a significant, ment, 2nd edn (ed EG Heyne), Agronomy Monograph qualitative difference in the composition of the con- 13. ASA-CSSA-SSSA, Madison, p. 243-254. stitutive heterochromatin (GILL 1987). Kellogg EA, (1989). Comments on genomic genera in the The obvious divergent chromosomal characters of Triticeae (Poaceae). Am. J. Bot. 76: 796-805. the four genera indicate that these are not closely Kellogg EA, Appels R and Mason-Gamer RJ, (1996). When genes tell different stories: the diploid genera of related and support their recognition as individual Triticeae (Gramineae). Syst. Bot. 21: 1-27. genera. Judged from their overall similarity in kary- Levan A, Fredga K and Sandberg, AA (1965). Nomencla- otype morphology there is some support for a ture for centromeric position on chromosomes. Heredi- closer relationship between Crithopsis and Tae- tas 52: 201-220. niatherum than between either of these genera and Linde-Laursen I, (1975). Giemsa C-banding of the chromo- somes of ‘Emir’ barley. Hereditas 81: 285-289. Psathyrostachys and Hordeum. In spite of this, the Linde-Laursen I, (1981). Giemsa banding patterns of the cladistic analyses of KELLOGG(1989) and FRED- chromosomes of cultivated and wild barleys. In: Barley ERIKSEN and SEBERG(1992, and unpubl.) suggest Genetics IV. Proc. 4th Int. Barley Genet. Symp.. Edin- that these genera are each other’s nearest relatives burgh 1981 (eds MJC Asher, RP Ellis, AM Hayter and among the Triticeae. RNH Whitehouse), Edinburgh Univ. Press, Edinburgh, The relationships of the four genera have recently p. 786-795. Linde-Laursen I, (1984). Nucleolus organizer polymor- been approached through the elaboration of gene phism in barley, Hordeum vulgare L. Hereditas 100: trees based on molecular markers. In the Triticeae 33-43. there is limited agreement between gene trees Linde-Laursen I and Baden C, (1994a). Giemsa C-banded derived from nuclear genes (the two 5s rDNA ar- karyotypes of two cytotypes (2x, 4x) of Psathyrostachys rays and ITS) and those derived from the chloro- lanuginosa (Poaceae; Triticeae). Hereditas 120: 1 13- 120. Linde-Laursen I and Baden C, (1994b). Comparison of the plast (cpDNA RFLPs and rpoA; KELLOGGet al. Giemsa C-banded karyotypes of the three subspecies of 1996; PETERSENand SEBERG1997), and both devi- Psathyrostachys fragilis, subspp. villosus (2x), secali- ate considerably from the morphologically based formis (2x, 4x), and fragilis (2x) (Poaceae), with notes on phylogenies. However, on gene trees where all gen- chromosome pairing. PI. Syst. Evol. 191: 183-198. era are included, Crithopsis and Taeniatherum as a Linde-Laursen I and Bothmer R von, (1984a). Identifica- rule belong to the same clade, which in addition tion of the somatic chromosomes of Psathyrostachys fragilis (Poaceae). Can. J. Genet. Cytol. 26: 430-435. includes several other taxa, mostly Aegilops L. Linde-Laursen I and Bothmer R von, (1984b). Somatic cell s.lat., but invariably excludes Psathyrostachys and cytology of the chromosome-eliminating, intergeneric Hordeum. PsathyroJtachys and Hordeum have a hybrid Hordeum vulgare x Psathyrostachys fragilis. basal position on the gene trees, often one or the Can. J. Genet. Cytol. 26: 436-444. other is sistergroup to the rest of the diploid Trit- Linde-Laursen I and Bothmer R von, (1986). Comparison of the karyotypes of Psathyrostachys juncea and P. iceae. This position is in contrast to their position huashanica studied by banding techniques. P1. Syst. on the morphologically derived gene trees (FRED- Evo~.151: 203-213. ERIKSEN and SEBERG1992, and unpubl.). Linde-Laursen I and Frederiksen S, (1989). Giemsa C- banded karyotypes of three subspecies of Taeniatherum caput-medusae and of two intergeneric hybrids with Psathyrostachys spp. (Poaceae). Hereditas 1 10: 283-288. ACKNOWLEDGEMENTS Linde-Laursen I, Bothmer R von and Jacobsen N, (1980). Giemsa C-banding in Asiatic taxa of Hordeum section Mrs. Elly Ibsen is thanked for her skilful technical assis- Stenostachys with notes on chromosome morphology. tance and Dr. Bo Johansen for his scanning of Fig. 1. Hereditas 93: 235-254. Hereditas 130 (1999) C-banded karvotvpe of Crithopsis delileanu 55

Linde-Laursen I, Bothmer R von and Jacobsen N, Sakamoto S, (1973). Patterns of phylogenetic differ- (1995). Karyotype differentiation and evolution in the entiation in the tribe Triticeae. Seiken Ziho 24: Il- genus Hordeum (Poaceae). In: Kew Chromosome 31. Conference IV (eds PE Brandham and MD Bennett), Sakamoto S and Muramatsu M, (1965). Morphological Royal Botanic Gardens, Kew, p. 233-247. and cytological studies on various species of Love A, (1984). Conspectus of the Triticeae. Feddes Gramineae collected in Pakistan, Afghanistan and Repert. 95: 425-521. . In: Results of the Kyoto University Scientific Morris KLD and Gill BS, (1987). Genomic affinities of Expedition to Karakoram and Hindukush, 1955, vol. I individual chromosomes based on C- and N-banding (ed K. Yamashita), p. 119-140. Cited after Sakamoto analyses of tetraploid species and their diploid (1973). progenitor species. Genome 29: 247-252. Xu J and Kasha KJ, (1992). Identification of a barley Petersen G and Seberg 0, (1997). Phylogenetic analysis chromosomal interchange using N-banding and in situ of the Triticeae (Poaceae) based on rpoA sequence hybridization techniques. Genome 35: 392-397. data. Molec. Phyl. Evol. 7: 217-230.