Synaptic variation derived plausible cytogenetical basis of rarity and endangeredness of endemic Mantisia spathulata Schult

Sharma, Santosh Kumar; Kumaria, Suman; Tandon, Pramod; Rao, Satyawada Rama

doi:10.1007/s13237-011-0033-1

Cited by 12 publications

(9 citation statements)

References 33 publications

(46 reference statements)

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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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“…Recently, Bhowmik et al (2010a) reported comparatively low in vivo germination of seeds for M. spathulata and M. wengeri (20 and 24 %, respectively). Other factors like, squat cross-pollination, entomophily (Bhowmik 2009), imbalanced meiotic events (Sharma et al 2011b), low karyo-morphological variation also depicts the confirma-tion of rarity and endangered status of both the species of genus Mantisia.…”

Section: Discussionmentioning

confidence: 78%

“…Mantisia species are annual or perennial herbs (Bhowmik et al 2009) and aerial shoots of these species used to appear after the development of inflorescence with numerous splendid flowers (Rahman and Yusuf 2002). Due to natural calamities and anthropogenic activities, M. spathulata and M. wengeri have become critically-endangered in the natural habitat (Ganeshaiah 2005, Tandon et al 2007, Bhowmik et al 2009, 2010a, Sharma et al 2011b and are listed in the Red Book of rare and endangered Indian plants (www.envfor.nic.in/bsi/research.html). Few reports are available for the phylogenetic analysis related to Mantisia and allied genus Globba (Takano andOkada 2003, Kress et al 2001).…”

Section: Introductionmentioning

confidence: 99%

Low genetic diversity as revealed by SPAR methods possibly leads to extinction of two critically-endangered and endemic species of Mantisia

Sharma¹,

Bhowmik²,

Kumaria³

et al. 2011

Biol Plant

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Mantisia spathulata Schult. and M. wengeri Fischer, two critically-endangered, endemic and rare species of the genus Mantisia (Zingiberaceae), have been rediscovered from Lunglei province of Mizoram, India, after two decades. For sustainable conservation and utilization of the Mantisia species, in vitro seed and clonal propagation methods have been developed earlier by our research group and plantlets have been reintroduced to their natural habitat for species recovery. To comprehend the plausible reasons for endemism and endangeredness of both the species at DNA level, they were analyzed to assess natural genetic variation using three different polymerase chain reaction (PCR) based DNA markers viz. random amplified polymorphic DNA (RAPD), inter simple sequence repeat (ISSR) and directed amplification of minisatellite DNA regions (DAMD), both individually and cumulatively, which are popularly regarded as single primer amplification reaction (SPAR) methods. A total of 107 primers belonging to three SPARs are used which collectively endow low genetic variation (15 and 20 %, respectively) in both M. spathulata and M. wengeri. The use and efficacy of SPAR methods to reveal the natural genetic variation in Mantisia species at intra-specific level has been recorded for the first time. To impede the extinction risk of these two species of genus Mantisia, large scale conservation strategies including in situ and ex situ conservation are recommended.

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“…Generally, the meiotic course in such asynaptic mutants is accompanied by a large number of meiotic anomalies such as scattered distribution of univalents in the cytoplasm, laggards at anaphases, unequal distribution of chromosomes at anaphases and multipolar PMCs. Several reserchers have reported a similar type of irregular behaviour as a result of asynaptic mutations (Koduru and Rao 1981, Kaul and Murthy 1985, Singh 2002, Sharma et al 2010, Kumar and Singhal 2012b, Kumar et al 2012.…”

Section: Discussionmentioning

confidence: 86%

High Pollen Sterility and 2n Pollen Grains in an Asynaptic 4x Cytotype (2n=48) of Solanum nigrum L.

et al. 2012

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Summary Cytological investigations have been carried out on the 9 wild accessions of Solanum nigrum L., a medicinally important species having wide-range therapeutic properties. Male meiotic studies performed in 9 accessions revealed the presence of 3 intraspecific cytotypes, 2x (n=12), 4x (n=24) and 6x (n=36) in the species. The course of meiosis in 8 of the 9 accessions among the 2x, 4x, 6x cytotypes was noticed to be perfectly normal resulting in very high pollen fertility (95-100%). However, 1 accession of 4x cytotype scored from Palchan (Solang Valley, Kullu, Himachal Pradesh) depicted irregular chromosomal behaviour during meiosis due to the presence of all 48 chromosomes as univalents. The further course of meiosis in this individual was highly irregular with the presence of large number of lagging and unoriented chromosomes, eccentric positioned univalents in the PMCs and unequal distribution of chromosomes at anaphase-I. Microsporogenesis was also abnormal which is characterized by the presence of irregular sporads, such as dyads, triads and polyads. Lagging chromosomes constituted micronuclei at sporad stages. Consequent to all these meiotic irregularities, 95% of the pollen grains were observed to be sterile. Pollen grains were also recorded to be of different sizes. In meiotically abnormal 4x accession, pollen grains were of 2 different types compared to normal 4x plants showing perfectly normal meiosis. The large pollen grains, which were measured to be 1.25-1.5 times bigger than normal sized pollen grains, were considered as unreduced or 2n pollen grains. The role of such 2n (unreduced) pollen grains in producing polyploid genotypes through sexual polyploidization in a chromosomally variable S. nigrum (2x, 3x, 4x, 5x, 6x, 8x, 9x, 12x) has also been discussed.

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Synaptic variation derived plausible cytogenetical basis of rarity and endangeredness of endemic Mantisia spathulata Schult

Cited by 12 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

Low genetic diversity as revealed by SPAR methods possibly leads to extinction of two critically-endangered and endemic species of Mantisia

High Pollen Sterility and 2<i>n</i> Pollen Grains in an Asynaptic 4<i>x</i> Cytotype (2<i>n</i>=48) of <i>Solanum nigrum</i> L.

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