New Zealand Journal of Botany

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Chromosome number in formosa ()

Z. Zulkarnain , A. Taji & N. Prakash

To cite this article: Z. Zulkarnain , A. Taji & N. Prakash (2002) Chromosome number in (Fabaceae), New Zealand Journal of Botany, 40:2, 331-333, DOI: 10.1080/0028825X.2002.9512792

To link to this article: http://dx.doi.org/10.1080/0028825X.2002.9512792

Published online: 17 Mar 2010.

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Download by: [180.254.165.196] Date: 23 April 2016, At: 18:49 New Zealand Journal of Botany, 2002, Vol. 40: 331-333 331 0028-825X/02/4002-0331 $7.00 © The Royal Society of New Zealand 2002

Short communication Chromosome number in Swainsona formosa (Fabaceae)

Z. ZULKARNAIN One of the impediments to commercialisation of A. TAJI Sturt's Desert Pea as a cut flower is the production of large amounts of pollen grains. This causes reduc- School of Rural Science and Agriculture tion in flower quality because of petal staining by University of New England pollen grains which are shed during transport. In Armidale, NSW 2351, Australia addition, pollination may occur during transport re- N. PRAKASH sulting in rapid degeneration of flowers and, thus, School of Environmental Sciences and Natural reduction in the vase life of the flowers. Our work Resources Management focuses on the production of male-sterile or University of New England plants with no pollen grains, by manipulating the Armidale, NSW 2351, Australia ploidy level and obtaining triploids. To our knowledge this is the first report of the chromosome number of Start's Desert Pea. It is part Abstract Chromosome number has been deter- of our comprehensive study on breeding systems of mined for Start's Desert Pea, Swainsona formosa, a this . Determining the diploid chromosome legume endemic to Australia. Mitotic chromosome number of untreated material allows us to assess the counts of 2n = 16 were found in root tip squashes success of treatment to induce polyploidy. and meiotic chromosome counts of n = 8 were found in microspore mother cells.

Keywords chromosome number; Fabaceae; MATERIALS AND METHODS ; Start's Desert Pea; Swainsona formosa; Plants used in this study were collected as seeds in formosus; legume South Australia, Australia, then germinated and propagated in a glasshouse. Voucher specimen NE 79130 is lodged in the NCW Beadle Herbarium, INTRODUCTION University of New England. Materials for root tip squash were sampled from seeds and materials for Sturt's Desert Pea, Swainsona formosa (G.Don) anther squash were taken from young flower buds. Downloaded by [180.254.165.196] at 18:49 23 April 2016 J.Thompson (syn. Clianthus formosus (G.Don) Ford Both seeds and flower buds were from 20 plants. & Vick.), is one of Australia's most spectacular wild flowers (Williams & Taji 1991) and is the floral Root tip squash emblem of South Australia. It has large flag-shaped Sixty seeds from 20 different plants were germinated flowers which are generally coloured bright red but in Petri dishes in a 16:8 h light:dark cycle and roots may be pure white to deep purple in some wild speci- from 3-day-old seedlings were collected 1 h after mens. The economic importance of this is in lights were switched on. These roots were immedi- its use as a hanging basket or container plant or as ately soaked in 0.1% colchicine solution for 4 h at cut flowers. It is in demand in the domestic cut room temperature to prevent spindle elongation. flower markets and is exported particularly to Japan. Roots were then rinsed with sterile distilled water and stored in 70% alcohol at 4°C until required. The roots were hydrolysed with stain-acid mix- tare (9 parts of 1% aceto-orcein + 1 part of 1N HCl) and gently heated over an alcohol flame for 1 min B01015 to help the uptake of the stain. The roots remained Received 26 April 2001; accepted 11 February 2002 in the stain-acid mixture for ± 10 min. The stained 332 New Zealand Journal of Botany, 2002, Vol. 40

The Swainsona is placed in the tribe Galegeae sub-tribe Coluteinea. Chromosome counts have been obtained from a number of Swainsona species. (Hair 1963) first reported chromosome number in S. novae-zelandiae { novae- zelandiae in Heenan (1998a)) as 2« = 32. The same chromosome count of 2« = 32 was also found in S. galegifolia (Ermayanti et al. 1993). In her revision of the genus, Thompson (1993) stated that Swainsona has a uniform chromosome number of 2« =32. (Heenan 1998b) also suggested that the chromosome number of Swainsona with standard modified as a boss is 2« = 32, but differs from a group of species lacking in modifications that have a chromosome number of 2« = 16 or 24. It seems that the chromosome number of 2n = 32 is common in Swainsona. However, the Australian genera in sub-tribe Coluteinea, , , Smirnowia, , and , Fig. 1 Polar view of meiotic chromosomes in the pollen all have species with 2« = 16 (Polhill & Raven mother cell of Swainsonaformosa (n = 8). Bar = 10 um. 1981). We suggest that the count of In =16 in S. formo sa favours the basic number of x = 8 in Swainsona and confirms the base chromosome meristematic tip was then excised (± 0.5 mm) on a number of x = 8 in Galegeae as previously proposed slide and macerated in a small drop of 1% aceto- by (Goldblatt 1991). orcein (without HCl), squashed, and gently warmed over an alcohol flame for 30 sec (Prakash 2000). Anther squash ACKNOWLEDGMENTS Twenty plants were selected as the sample of plant materials. Anthers from young flower buds (13.7— We thank Murray I. Dawson for advice and comments on the draft manuscript, and assistance in finding the 13.9 mm long) were squashed in a few drops of 1% relevant literature; and an anonymous referee for critical aceto-orcein (without HO) and gently warmed over comments on the draft manuscript. an alcohol flame for 30 sec (Prakash 2000). Slides were examined under a microscope, and 4- 6 cells from each sample were counted to ensure that

Downloaded by [180.254.165.196] at 18:49 23 April 2016 a consistent count was achieved. Chromosomes were REFERENCES photographed with Kodak ASA 400 film and scanned with a Hewlet Packard ScanJet 4200C scan- Ermayanti, T. M.; McComb, J. A.; O'Brien, P. A. 1993: ner. Whole images were then manipulated with Cytological analysis of seedling roots, transformed Adobe PhotoDeluxe Home Edition 3.0 for clearer root cultures and roots regenerated from callus of viewing. (Andr.) R. Br. Journal of Experimental Botany 44: 375-380. Goldblatt, P. 1991: Cytology and the phylogeny of Leguminosae. In: Polhill, R. M.; Raven, P. H. ed. RESULTS AND DISCUSSION Advances in legume systematics II. Kew, Royal Mitotic chromosomes at metaphase were examined, Botanic Gardens. but they were too small for karyotype analysis. Al- Hair, I. B. 1963: Contributions to a chromosome atlas of though photographs were not clear enough for count- the New Zealand flora—6. Miscellaneous fami- ing of chromosomes, counting under the microscope lies. New Zealand Journal of Botany 1: 243-257. indicated that 2« = 16. A clearer photograph was ob- Heenan, P. B. 1998a: Montigena (Fabaceae), a new genus tained from an anther squash showing that n = 8 in endemic to New Zealand. New Zealand Journal the pollen mother cell (Fig. 1). of Botany 36: 41-51. Zulkarnain et al.—Chromosome number in Swainsona formosa 333

Heenan, P. B. 1998b: Phylogenetic analysis of the complex, Clianthus, and Swainsona (Fabaceae), from Australia and New Zealand. New Zealand Journal of Botany 36: 21-40. Polhill, R. M.; Raven, P. H. 1981: Advances in legume systematics I. Kew, Royal Botanic Gardens. Pp. 357-360. Prakash, N. 2000. Methods in plant microtechnique. 3rd ed. Armidale, NSW, University of New England. Thompson, J. 1993; A revision of the genus Swainsona (Fabaceae). Telopea 4: 427-582. Williams, R.; Taji, A. 1991: Start's Desert Pea in review. Australian Horticulture 89: 85-88. Downloaded by [180.254.165.196] at 18:49 23 April 2016