Chromosome studies in the family Magnoliaceae.

Biswas, Biswajit; Sharma, Arun Kumar

doi:10.1508/cytologia.49.193

Cited by 8 publications

(4 citation statements)

References 9 publications

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“…Furthermore, besides the presence of palaeoploidy and high basic numbers certain families and genera are characterized by the evolution of well developed polyploid series. Notable among these are Alangium (2x,3x), et al, 1982;OHRI, 1996) , 1986), Magnolia (2x,4x,6x) (BISWAS and SHARMA, 1984;PARRIS et al, 2010), Annona (2x,4x), Cochlospermum (2x,3x,4x,6x), Barringtonia (2x,4x) (MORAWETZ, 1986), and Betula (2x,4x,6x,10x) (FURLOW, 1990), Leucaena (2x,4x) (PALOMINO et al, 1995), Trigonobalanus (2x,6x) (CHEN et al, 2007), Desoxylum (2x,8x) (KHOSLA and STYLES, 1975), Aglaia (2x,4x) , Urvillea (2x,4x,8x) (FERRUCCI, 2000, URDAMPILLETA et al, 2006.…”

Section: Inter and Intraspecific Polyploidymentioning

confidence: 99%

How small and constrained is the genome size of angiosperm woody species

Ohri

2015

Silvae Genetica

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Angiosperm hardwood species are generally considered to show an average smaller genome size with a narrow range of variation than their herbaceous counterparts. Various explanations pertaining to limitations of cell size exerted by wood fibers, the requirement of smaller stomata, longer generation time, large population size, etc., have been put forward to account for their small and constrained genome size. Yet studies done in the past several years show that genomically as well as evolutionarily, hardwoods are as diverse and active as their herbaceous counterparts. This is entirely supported by the presence of well developed inter and intraspecific polyploid series and natural triploidy in many genera. Polyploidy, in some instances has been shown to confer adaptability to arid and salt stress conditions and in colonization of new areas. Moreover, hardwoods also show reasonable amenability to the induced polyploidy which abruptly changes the balance between nuclear and cell size. Polyploidy has been induced in many hardwoods to restore fertility in interspecific hybrids and for the production of triploids.Furthermore, some cases studied show that genome size variation in hardwoods can be as variable as that of herbaceous species. Genome size has been shown to vary remarkably both at homoploid level as well as by polyploidy in certain genera. In the same way, the genome size is not correlated with the habit in certain groups having both herbaceous and woody taxa. This point is further proved by the presence of secondary and insular woody habit in certain cases where either the transition to woodiness is not followed by any diminution in the genome size, or the genome size of insular woody species may be even more than that of the congeneric herbaceous species. This shows that woody habit does not by itself put any constraints on the genome size either at homoploid or at polyploidy levels. The genome size in fact, not only varies significantly in many congeneric woody species but also may not show any correlation with the habit when woody and herbaceous species are compared in some narrow taxonomic groups studied.

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Section: Inter and Intraspecific Polyploidymentioning

confidence: 99%

How small and constrained is the genome size of angiosperm woody species

Ohri

2015

Silvae Genetica

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“…The occurrence of a pentavalent in the material at meiosis may be considered as a positive evidence of the pentaploid nature of the taxon. As for M. liliflora, the chromosome numbers reported earlier are 2n=38 (Chen et al 1984, Huang et al 1985 and 2n=78 (Janaki Ammal 1952, Biswas 1979, Biswas and Sharma 1984. The finding of 95 bivalents (2n=190) in the present material shows that this is a new polyploid cytotype (10x) of the species in the x=19 basic line.…”

Section: Discussionmentioning

confidence: 89%

New Polyploid Cytotypes in Species of Magnolia.

Valsaladevi

Mathew

1998

CYTOLOGIA

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Summary Meiosis in two species of Magnolia from South Indian, namely M. obovata and M. liliflora, has been studied. Meiosis in the former was abnormal due to formation of multivalents (penta-, quadri-and trivalent) along with bivalents and univalents together making up a count of 2n=95, while meiosis in the latter was normal with regular formation of 95 bivalents (2n=190). The findings show that the present materials of the two species are new polyploid cytotypes, M obovata 5x and M liliflora 10x on x=19. The n=95 reported here in M liliflora is the highest chromosome number known in the Magnoliaceae. On the speculation that the x=19 in the Magnoliaceae could be a derived one of tertiary origin, representing a 'paleo 6x' state, the present cytotypes of M obovata and M. liliflora may be reckoned as representing very high 'paleopolyploids'-15x and 30x respectively.The genus Magnolia L. (Magnoliaceae) has over 80 species which are deciduous or evergreen trees and shrubs distributed in the Northern Hemisphere. Great bulk of them occur in the temperate and tropical South-East Asia, and many species are horticulturally important. Indian species are mostly confined to the Himalayan region; and in South India a few species occur as introduced plants in some high altitude localities like Munnar (Kerala) and Kodaikanal (Tamil Nadu). The earliest known chromosome report in the genus is the one in a Japanese species (M. foetida) as early as 1916 by Yamakawa (Federov 1969). Janaki Ammal (1952) has reported the chromosome numbers in a number of species. This paper reports new polyploid cytotypes in two species. M obovata Thumb. and M. liliflora Desr. from South India. Materials and methodsChromosomes of the two species are studied from PMCs at meiosis of materials procured from Kodaikanal, a high elevation (1500 m) hill resort in the South Indian State of Tamil Nadu. The plants of both the species are known to be of East sub-Himalayan origin. The voucher specimens are conserved at the Kerala University Department of Botany, Trivandrum. Young flower buds were fixed in 1 : 3 acetic alcohol, and chromosome preparations were made by the simple acetocarmine (2%) smear technique. Observations of meiotic behaviour and chromosome counts were made from a number of PMCs at division. Pollen fertility was assessed on the basis of stainability of mature pollen grains in 1 : 1 mixture of acetocarmine and glycerine. ObservationsMagnolia obovata Thumb.Meiosis in the material was not normal due to formation of multivalents and univalents, and consequent irregular separation of chromosomes at anaphase resulting in very low pollen fertility (31 %). Analysis of associations of chromosomes at diakinesis and metaphase-I showed penta-, Former Head,

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“…The chromosome structure among Magnolia species varies little and the karyotypes of all the species remain constantly at type 2B (Stebbins 1971, Okada 1975, Biswas and Sharma 1984, Li et al 1998. The chromosome behavior during meiosis is usually examined to determine the numerical and structural features of chromosomes.…”

mentioning

confidence: 99%

“…The chromosome number is 2n=4x=76 (Whitaker 1933, Biswas and Sharma 1984, Li et al 1998. M. liliiflora Desr.…”

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confidence: 99%

Cytological Study of Tetraploid Species of <i>Magnolia</i> subgenus <i>Yulania</i> (Magnoliaceae)

Wang

Ejder

et al. 2016

CYTOLOGIA

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Summary Cytological studies were conducted on five tetraploid species plus two varieties of Magnolia subgenus Yulania and a hybrid between two of these species. Two different chromosome configurations in meiosis are observed in this article. The first group was typical for M. acuminata, M. liliiflora and their relatives which share several cytological characteristics including chromosome configurations and behavior in meiosis. The cytological evidence indicate autotetraploid origin for these species, despite the homologous chromosomes likely having changed their structures causing the formation of heteromorphic multivalents, chromosome bridges and fragments during meiosis. The second group of chromosome configuration was found in M. cylindrica and M. concinna. These species were characterized by very rare trivalents and tetravalents. These observations suggest these taxa as allotetraploids which may have been formed from hybridisation between hexaploid and diploid parents as deduced from trivalents observed at some rate. Multivalent formation and possible translocations and inversions of chromosomes in M. liliiflora influence its propagation by causing low fertility. M. liliiflora is probably a comparatively new species with an unstable chromosome constitution and is growing only in small populations at low elevation. It is vulnerable, and the species could already be extinct in nature. On the other hand, M. acuminata shows a more regular chromosome behavior and fewer abortion spores than M. liliiflora, and should be a more stable species with longer evolution time. Thus, the superior fertility of M. acuminata has enabled it to develop a stable and extensive distribution from NE to SE USA.

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Chromosome studies in the family Magnoliaceae.

Cited by 8 publications

References 9 publications

How small and constrained is the genome size of angiosperm woody species

How small and constrained is the genome size of angiosperm woody species

New Polyploid Cytotypes in Species of Magnolia.

Cytological Study of Tetraploid Species of <i>Magnolia</i> subgenus <i>Yulania</i> (Magnoliaceae)

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