Cytotaxonomic Studies in Apocynaceae and Delineation of the Different Evolutionary Tendencies Operating within the Family

Tapadar, N. N. Roy

doi:10.1080/00087114.1964.10796120

Cited by 19 publications

(11 citation statements)

References 20 publications

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“…This procedure is contrary to the one employed by some cytologists who dealt with Apocynaceae. Roy Tapadar and Sen (1960), Tapadar (I 964) and Banerjee (1974) distinguished differences in length of 0.1 ~am, but Datta and Maiti (1972) even registered differences as small as 0.01 #m. The accuracy pursued by these authors is of disputable value: the length of the chromosomes of A Ilamanda cathartiea rangesaccordingto RoyTapadar and Sen (1960) from 1.5 to 4.1 ~m, whereas the first author in a later publication (Roy Tapadar, 1964) mentions a range of 2.1 to 4.8 ~m for this species. Table 1 shows that the size of the somatic metaphase chromosomes of most of the species analysed in this study fall in a range of l to 2 #m. Longer chromosomes (l to 3 #m) occur in the tribe Tabernaemontaneae.…”

Section: Chromosome Length and Karyoope Morphologymentioning

confidence: 90%

“…In order to reduce the size of the reference list, most references already included in other collective documents have been omitted in this paper. These documents are the publications of Roy Tapadar (1964), Fedorov (1969, Datta and Maiti (1972), R. J. Moore ( 1973Moore ( , 1974Moore ( , 1977 and Goldblatt (1981 and.…”

Section: Chromosome Numbers; Other Reports Andsvnonymsmentioning

confidence: 97%

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Cytotaxonomy of the apocynaceae

Laan

Arends

1985

Genetica

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At present there is karyological information on ca 10% of the species and ca 30% of the genera of the Apocynaceae. Basic numbers of x = 6, 8, 9, I 0, 11, 12, 16, 18, 20, 21 and 23 have been assessed. Of these x = 11 is primitive, occurring in ca 60% of the genera.Those ofx = 6, 8, 9 and 10 have evolved by reduction, and x = 12 by increase from x = 1 I. In the subtribe Secondatiinae however, x = 12 is most likely the result of doubling x = 6. The numbers x = 16, 18 and 20 are likewise doubles of x = 8, 9 and 10 respectively. Those of x = 21, 23, and in one case, x = 20 are probably aneuploid products of doubles of x = 11.The two larger subfamilies, Plumerioideae and Apocynoideae have the basic numbers.x = 8, 9, 10 and 11 in common and are not separable on the basis of chromosomal evidence. The third small subfamily Cerberoideae is more homogeneous according to basic number, i.e. x = 10 and 20. Most genera are characterized by a constant basic number, but some have two basic numbers; these clearly are cases of infrageneric aneuploidy.Based on records in the literature two closely related genera Apocynum and Trachomitum appear to be characterized by a basic number of x = 8 as well as x = 1 i. This conflicting situation should be clarified by further karyological research. From the level of subtribe onwards some taxa have one basic number, but others are characterized by two or more numbers. The occurrence of similar basic numbers in different phylads of the family is considered to be the result of similar chromosomal evolution mechanisms.Approximately 22% of the investigated species are polyploid. Intrageneric polyploidy occurs with a frequency of about 12.5% and infraspecific polyploidy with less than 4%.The karyotypes observed are symmetrical: the chromosomes within a karyotype are similar in length with primary constrictions usually in a median position. In the Tabernaemontaneae however, it was observed that the karyotypes comprise one pair of distinctly heterobrachial chromosomes in addition to the metacentric ones. This tribe is also characterized by chromosomes which are relatively long.Most genera of the African continent, which are well known regarding their chromosome number, are characterized by x = ! 1. Exceptions are Strophantus (x = 9) with a mainly tropical African distribution. Two other genera with derived numbers, i.e. Gonioma with x = I 0 and Pachypodium with x = 9, occur in southern Africa and Madagascar. The genera with a non-African distribution are less known for their chromosome number. However, the available evidence suggests that evolution of derived numbers has occurred more frequently outside Africa than on this continent.

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Section: Chromosome Length and Karyoope Morphologymentioning

confidence: 90%

Section: Chromosome Numbers; Other Reports Andsvnonymsmentioning

confidence: 97%

Cytotaxonomy of the apocynaceae

Laan

Arends

1985

Genetica

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“…1). The previous reports revealed 22 somatic chromosomes in wild type T. coronaria (Roy Tapadar and Sen 1960, Roy Tapadar 1964, Dutta and Maity 1972. The chromosomes are mostly medium in size in three varieties ranging between 1.45 to 4.04 μm in length.…”

Section: Cytological Datamentioning

confidence: 99%

“…The chromosome complement of this species has been found to be homogeneous with 2n=22 and n=11 (Roy Tapadar and Sen 1960, Roy Tapadar 1964, Dutta and Maity 1972 except one report by Van der Laan and Arends (1985), where they found 2n=33 chromosomes. The different species of this genus contain 2n=22 chromosomes revealing basic number to be x=11 (Van der Laan and Arends 1985).…”

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confidence: 99%

Karyomorphological Analysis of Different Varieties of <i>Tabernaemontana coronaria</i>

et al. 2015

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Summary Tabernaemontana coronaria of Apocynaceae is an economically important medicinal plant, distributed throughout the tropics of the world. The different alkaloids produced by this species are effective against various disorders like abdominal tumors, asthma, diarrhoea, epilepsy, eye infections and fever. Morphological characters including internode length, petiole length, leaf area and leaf index varied between these varieties. Cytological analysis revealed three diploid varieties with 2n=22 chromosomes (Wild type T. coronaria, T. coronaria var. Variegata, T. coronaria var. Dwarf) and a triploid variety with 3n=33 chromosomes (T. coronaria var. Florepleno). A variation was recorded in total chromosome length and volume among the diploid varieties of T. coronaria. Most of the centromeric chromosomes were either median or median region. The present study indicated that cryptic structural changes of chromosomes might be responsible in the evolution of different varieties of T. coronaria except the Flore-pleno variety. Moreover, differential condensation of chromosomes attributing to variable chromosome length and volume has been suggested.

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“…Chromosomal analysis has been viewed as an important tool for establishing variability but owing to difficulty in the study of chromosomes of tree species, no attention has been paid so far in this genus. Although there are reports on the chromosome counts (Gajapathy 1962, Raman and Kesavan 1963, Tapadar and Roy 1964, Mehra and Bawa 1969) of these species but no studies have been carried out on chromosome complements. Thus the present investigation was undertaken with an aim to carry out cytogenetic analyses of these 2 important tree species of Aravallis in Rajasthan, in order to gain valuable information on genetic basis of interspecific variations in the genus Wrightia.…”

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confidence: 99%