Impaired Male Meiosis due to Irregular Synapsis Coupled with Cytomixis in a New Diploid Cytotype of Dianthus angulatus (Caryophyllaceae) from Indian Cold Deserts

Kumar, Puneet; Singhal, Vijay Kumar; Kaur, Dalbir

doi:10.1007/s12224-011-9107-8

Cited by 45 publications

(28 citation statements)

References 33 publications

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“…In a number of plants earlier workers have reported that synaptic mutation causes pollen sterility [15, 31, 36–38, 69–72]. However, in the present study pollen fertility was not affected seriously and was quite high (92%) which may be due the fact that dyads produced through restitution nuclei are genetically balanced which lead to a higher degree of pollen fertility.…”

Section: Discussioncontrasting

confidence: 77%

Erratic Male Meiosis Resulting in2nPollen Grain Formation in a 4x Cytotype (2n=28) ofRanunculus laetusWall. ex Royle

Kumar

Singhal

2012

The Scientific World Journal

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Two accessions were studied for male meiosis in Ranunculus laetus from the cold regions of Northwest Himalayas. One accession showed the presence of 14 bivalents at diakinesis and regular segregation of bivalents at anaphase I which lead to normal tetrad formation with four n microspores and consequently n pollen grains and 100% pollen fertility. Second accession from the same locality revealed the erratic meiosis characterized by the presence of all the 28 chromosomes as univalents in meiocytes at metaphase I. Univalent chromosomes failed to segregate during anaphases and produced restitution nuclei at meiosis I and II. These restitution nuclei resulted into dyads and triads which subsequently produced two types of apparently fertile pollen grains. On the basis of size, the two types of pollen grains were categorized as n (normal reduced) and 2n (unreduced, 1.5-times larger than the n pollen grains). The estimated frequency of 2n pollen grains from dyads and triads (61.59%) was almost the same as that of the observed one (59.90%), which indicated that 2n pollen grains in R. laetus were the result of dyads and triads. The present paper herein may provide an insight into the mechanisms of the formation of various intraspecific polyploids through sexual polyploidization in R. laetus.

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Section: Discussioncontrasting

confidence: 77%

Erratic Male Meiosis Resulting in2nPollen Grain Formation in a 4x Cytotype (2n=28) ofRanunculus laetusWall. ex Royle

Kumar

Singhal

2012

The Scientific World Journal

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“…The occurrence of different meiotic abnormalities at the intra-population level indicates the intraspecific genetic diversity among these species. Similar observations have also been made lately in different plant species by Sheidai et al (2003), Gupta et al (2009), Kumar (2011), Kumar et al (2012), etc. In case of P. orientale, an association of four chromosomes (35% of PMCs) forms a translocation ring at diakinesis (Fig.…”

Section: Meiotic Abnormalitiessupporting

confidence: 85%

Meiotic Studies in Some Species of <i>Pennisetum</i> Pers. (Poaceae) from the Western Himalayas

Kaur¹,

Mubarik²,

Kumari³

et al. 2014

CYTOLOGIA

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Summary At present, cytological studies have been carried out on a population basis for assessing the genetic diversity in seven species of the genus Pennisetum, P. alopecuroides (n = 18), P. americanum (n = 7), P. flaccidum (n = 27), P. lanatum (n = 18, 21), P. orientale (n = 18), P. purpureum (n = 14, 18, 21) and P. ramosum (n = 5), from phytogeographically different areas of Himachal Pradesh and Kashmir in the Western Himalayas. For P. lanatum and P. purpureum, the chromosomal counts of n = 21 make first ever records of new cytotypes on a worldwide basis. In addition, P. lanatum and P. purpureum with n = 18 make new records in India. Both the cytotypes of P. lanatum and three different cytotypes of P. purpureum show some marked differences in their morphological features. Meiotic course is abnormal in almost all the species. The vary basis of the intraspecific genetic diversity, i.e. the variability of chromosome numbers, has been discussed not only for the Western Himalayas taxa, but also on India basis in light of worldwide data, pointing out slight differences in various parameters.

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“…A number of genotypes with different levels of abnormal meiotic behavior caused by extreme cold and xeric conditions have been evaluated in the plants of cold deserts of Pangi Valley, Chamba District, Himachal Pradesh. Already a large number of meiotic irregularities due to cold stress conditions affecting pollen size and fertility have been detected in the plants of the cold deserts of Lahaul‐Spiti and Kinnaur District of Himachal Pradesh (Kumar & Singhal, 2008; Kumar et al, 2008, 2010, 2011; Singhal & Kumar, 2008, 2010; Singhal et al, 2008, 2009; Singhal & Kaur, 2009; Kaur & Singhal, 2010). In the present study we report the occurrence of syncyte formation due to the fusion of two PMCs during the early stages of prophase I in L. longiflora , whereas the fusion of more than two cells forming syncytes have also been recorded in Brachiaria decumbens Stapf and Brachiaria jubata (Fig.…”

Section: Discussionmentioning

confidence: 99%

Syncytes during male meiosis resulting in 2n pollen grain formation in Lindelofia longiflora var. falconeri

Singhal

Rana

Kumar

2011

J of Sytematics Evolution

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Lindelofia longiflora (Royle ex Benth.) Baill. var. falconeri (Cl.) Brand (Family: Boraginaceae) is investigated cytologically (n= 12) for the first time from the cold deserts of Pangi Valley, Chamba District (Himachal Pradesh) in India. We report the formation of syncytes and 2n pollen grains in the species. During meiosis, the majority of the pollen mother cells (PMCs) exhibited 12 bivalents, equal segregation of chromosomes during anaphases, regular tetrads, and normal‐sized pollen grain formation. Occasionally, two proximate PMCs fused during the early stages of prophase‐I and resulted in the formation of syncytes. The frequency of syncytes in the accession is rather low, at 25 out of 1866 (1.33%). Such syncyte PMCs are detectable during meiosis due to their larger size compared to typical PMCs. The syncytes or polyploid cells showed normal 24 bivalents and depicted perfectly regular meiotic course. But the products of such PMCs yield 2n or larger sized pollen grains that are almost double the size of typical normal or n pollen grains. The origin of syncytes as a consequence of the fusion of meiocytes during the early stages of meiosis‐I could be attributed to low temperature stress conditions prevailing in the Pangi Valley, where temperature during May and June dip to below freezing, the time the plants enters the reproductive/flowering bud stage. It is possible that such apparently fertile 2n pollen grains originating from syncytes might play a role in the origin of intraspecific polyploids in the species.

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Impaired Male Meiosis due to Irregular Synapsis Coupled with Cytomixis in a New Diploid Cytotype of Dianthus angulatus (Caryophyllaceae) from Indian Cold Deserts

Cited by 45 publications

References 33 publications

Erratic Male Meiosis Resulting in2nPollen Grain Formation in a 4x Cytotype (2n=28) ofRanunculus laetusWall. ex Royle

Erratic Male Meiosis Resulting in2nPollen Grain Formation in a 4x Cytotype (2n=28) ofRanunculus laetusWall. ex Royle

Meiotic Studies in Some Species of <i>Pennisetum</i> Pers. (Poaceae) from the Western Himalayas

Syncytes during male meiosis resulting in 2n pollen grain formation in Lindelofia longiflora var. falconeri

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