Cytologia 41: 23-30, 1976
Cytological Observations on some W. Himalayan Monocots lll. Alliaceae
P. N. Mehra and S. K. Sachdeva Departmentof Botany,Panjab University, Chandigarh, India
Received May 16, 1974
The family Alliaceae is represented by a single genus Allium in the W. Himalayas. A perusal of the literature reveals that this genus has been fairly well investigated since it yields ideal material for cytological studies. Cytological data of about 300 species out of a total of nearly 450 is available (cf. Fedorov 1969). Although as many as 20 species are reported to occur in the W. Himalayas (Hooker 1894), no comprehensive attempt has so far been made to study the cytology of these in any great detail. The present communication reports the data on five species only. The results on more species from this region and also from the eastern wing of the Himalayas will be published later.
Material and methods
Collections were made from two distant areas i.e. Kashmir and Kumaon hills.
Specific localities with their altitude are given in Table 1. Voucher specimens have been deposited in the Herbarium, Department of Botany, Panjab Univer
sity, Chandigarh. The technique adopted is the same as mentioned in our previous
paper (Mehra and Sachdeva in this Journal). The photomicrographs are made at a uniform magnification of •~1500.
Observations
The chromosome numbers of the five species are presented in Table 1.
Allium blandum Wall occurs in the interior ranges of Kashmir hills at an altitude
of 2,700-3,300m. The chromosome number was determined both from PMC's
and root-tip mitoses. PMC's revealed n=16 at M1 (Fig. 1). Meiosis was normal.
Root-tip mitoses showed 2n=32 (Figs. 2, 2a). The karyotype consists of eight
pairs of median, seven pairs of submedian and one pair of subterminal chromo somes (Fig. 8). None of the chromosomes revealed any secondary constriction.
Chromosome size ranges from 10ƒÊ to 6ƒÊ.
A. consanguineum Kunth. is widely distributed in the Kashmir hills at 2,700
- 3,000m. PMCs revealed n=8 (Fig. 3). Meiosis was regular. Root-tip cells
showed 2n=16 (Figs. 4, 4a). The karyotype is highly symmetrical with four pairs
of median and four pairs of submedian chromosomes (Fig. 9). No secondary con
striction was observed. The chromosome size ranges from 10ƒÊ to 6ƒÊ.
A. stracheyi Baker grows commonly in the valley of flowers in Almora District
from where the material was collected. Somatic chromosome number was found 24 P. N. Mehra and S. K. Sachdeva Cytologia 41
to be 2n=16 (Figs. 5, 5a). The karyotype consists of three pairs of median, four
pairs of submedian and one pair of subterminal chromosomes (Fig. 10). The chromosome size ranges from 12ƒÊ to 7ƒÊ.
A. tuberosum Roxb. is cultivated in the Kumaon hills at an altitude of 1,500
- 1,800m. Meiotic chromosome number as determined from PMCs was found to
be n=16 (Figs. 6, 6a).
Table 1.
* Species investigated for the first time. •ª New chromosome number report. ** Literature cited from Chromosome Census of the Plant Ki ngdom I, Monocotyledons. Compiled by Archna Sharma, Nucleus: Vol . 15 (iii) 1972.
A. victorialis L. occurs in the Kashmir hills at 2 ,700-3,000m. The chromo somes were studied only from root-tip mitoses which showed 2n=16 (Figs . 7, 7a). The karyotype consists of one pair of median , six pairs of submedian and one pair of subterminal chromosomes (Fig . 11). One pair with submedian primary con striction also possesses a subterminal secondary constriction in the long arm . Maj ority of the chromosome pairs were heteromorphic , individual chromosomes of a pair varying in length and arm ratio (Fig. 11). The chromosome size ranges from 18ƒÊ to 10ƒÊ. 1976 Cytological Observations on some W. Himalayan Monocots III 25
Discussion
Of the five species of the genus Allium, presently studied, n=16, 2n=32 for A. blandum and n=8, 2n=16 for A. consanguineum furnish the first cytological reports for the species. The present report of 2n=16 for A. stracheyi is at variance with
Figs. 1-4. 1-2. Allium blandum; 1, Mr showing 16 bivalents, 2, root-tip mitosis showing 2n=32.
3-4. A. consanguineum; 3, MI showing 8 bivalents, 4, root-tip mitosis showing 2n=16. All •~1 500. 26 P. N. Mehra and S. K. Sachdeva Cytologia 41 the finding of Sharma and Aiyangar (1961) who observed 2n=14+2-10B; 28. The count of 2n=16 for A. victorialis is in conformity with the report of Levan (1935), Sato (1942), Ono (1960) and Love and Love (1961). However, Matsuura and Suto (1935) and Sokolovskaya (1963) recorded a tetraploid race in this species
Figs. 5-7. 5, Allium stracheyi, 2n=16 in root-tip mitosis. 6, A. tuberosum, n=16 at MI. 7, A. victorialis, 2n=16 in root-tip mitosis. All•~1500.
with 2n=32. The present report of n=16 for A. tuberosum conforms to the find
ings of Kurita (1962).
Three different base numbers 7, 8 and 9 have been reported in the genus (Dar
lington and Wylie 1955). Thus, with the exception of A. blandum and A. tuberosum 1976 Cytological Observations on some W. Himalayan Monocots III 27
Figs. 2a, 4a, 5a, 6a and 7a. Explanatory diagrams to Figs. 2, 4, 5, 6 and 7 respectively. 28 P. N. Mehra and S. K. Sachdeva Cytologia 41
which are tetraploids, the remaining three species are at diploid level. Amongst the diploid species A. consanguineum possesses the most primitive karyotype with
Figs. 8-11, Idiograms. 8, Allium blandum , 2n=32. 9, A. consanguineum, 2n=16. 10 , A. stracheyi, 2n=16. 11, A. victorialls, 2n=32 . 1976 Cytological Observations on some W. Himalayan Monocots III 29 four pairs of median and four pairs of submedian chromosomes; a little advanced condition exists in A. stracheyi which possesses three pairs of median, four pairs of submedian and one pair of subterminal chromosomes; and the most advanced condition is exhibited in A. victorialis with one pair of median, six pairs of sub median and one pair of subterminal chromosomes. Sato (1942) worked out the karyotype of A. victorialis subspecies platyphyllum in which he observed fourteen pairs of long chromosomes with median or submedian primary constriction and two pairs of short chromosomes with subterminal primary constriction. In A. victorialis individual chromosomes of a majority of the pairs were found to vary greatly in length and arm ratio, which could be due either to translocations or the hybrid nature of the taxon. The tetraploid species A. blandum possesses a symmetrical karyotype. The occurrence of only one pair of subterminal chromosomes in the complement of this species suggests either its origin from different parental sources or chromo somal repatterning.
Summary Five W. Himalayan species of the genus Allium have been studied. Two spe cies, A. blandum (2n=32) and A. consanguineum(2n=16) have been investigated for the first time. A. stracheyi was found to possess 2n=16. In the somatic com plement of A. victorialis the individual chromosomes of most of the pairs were found to be unequal varying greatly in length and arm ratio which is suggestive either of unequal translocations or hybrid nature of the taxon. The presence of only one pair of subterminal chromosomes in the complement of the tetraploid spe cies A. blandum suggests its origin either from different parental sources or chromo somal repatterning which seems more probable.
Acknowledgements We gratefully acknowledge the financial assistance from U.S. Department of Agriculture under PL 480 Project (Grant No. FG-In-281) to the senior author. Our thanks are due to the Head of the Division of Botany, F. R. I., Dehradun for help in the identification of plants. We are also thankful to the Atomic Energy Commission for providing the laboratory facilities at High Altitude Research Laboratory, Gulmarg.
Literature cited
Darlington, C. D. and Wylie, A. P. 1955. Chromosome Atlas of Flowering Plants. George Allen and Unwin Ltd., London. Fedorov, An. A. (Ed.) 1969. Chromosome Numbers of Flowering Plants. Leningrad. Hooker, J. D. 1894. The Flora of British India. Vol. VI. L. Reeve and Co., London. Kurita, M. 1962. Extreme fragmentation of meiotic chromosomes in Allium tuberosum. Mem. Ehime. Univ. Sec. II. Ser. B. 4: 395-401. Levan, A. 1935. Cytological studies in Alliums VI. Hereditas 22: 289-330. 30 P. N. Mehra and S. K. Sachdeva Cytologia 41
Love, A. and Love, D. 1961. Chromosome numbers of Central and Northwest European plant species. Opera Botanica 5: 1-581. Matsuura, H. and Suto, T. 1935. Contributions to the idiogram study in phanerogamous plants. Jap. Jour. Fac. Sci. Hokkaido. Imp. Univ. Ser. V. 5: 33-75. Ono, R. 1960. Cytological effects of extracts from noxious plants I. Meiotic abnormalities induced by the treatment of water extracts from Cicuta virosa L. in Allium victorialis subsp. platyphyllum Hulten. Jap. Jour. Genet. 35: 120-124. Sato, D. 1942. Karyotype alteration and phylogeny in Liliaceae and allied families. Jap. Jour. Bot. 12: 57-161. Sharma, A. K. and Aiyangar, H. R. 1961. Occurrence of B-chromosomes in diploid Allium stra cheyi and their elimination in polyploids. Chromosoma 12: 310-317. Sokolovskaya, A. P. 1963. Geographical distribution of polyploidy in plants. (Investigation of the flora of the Kamchatka Peninsula). Vest. Leningrad. Univ. 1963, No. 15, Ser. Biol. 38-52.