Induced Desynaptic Male Sterile Lines in Soybean

Abstract

SummaryIn a study on soybean using gamma rays, we came across with some sterile mutants. Cytological studies of these mutants clearly revealed desynapsis in them. In these sterile plants only few bivalents and a high frequency of univalents have been recorded and they displayed a very high percentage of pollen sterility. Later meiotic stages were also found to be highly disturbed. The plants were identified as male sterile ones as few pods were formed. It might be possible that gamma rays have acted on some genes responsible for synapsis and chiasma formation and resulted in early chiasmate dissociation suggesting that gamma rays can act as a potential tool in the development of male sterile lines. Study of desynaptic mutants is a potentially important source of information on the chiasma maintenance mechanism. These mutants furthermore can provide useful cytological and genetical informations on the male sterility occured in higher plants.Key words Soybean, Desynapsis, Chromosomal abnormalities, Male-sterility, Gamma-rays.Meiosis occupies a central role in the life cycle of all sexually reproducing eukaryotes, and it is through this process that eukaryotes achieve chromosome reduction, ordered chromosome segregation into haploid products and recombination of chromosomes. This involves a complex orchestration of events including chromosome pairing at zygotene, genetic exchange at pachytene, chiasmata formation at diplotene and chromosome segregation at anaphase I and II (Franklin et al. 1999). At least one chiasmata per bivalent is essential for orderly disjunction, otherwise, some homologues may migrate to same pole and form aneuploid gametes. The pairing and recombination of chromosome is under genetic control (Rees 1961). A mutation in the genes controlling the meiotic recombination may lead to failure or early dissolution or reduction of chiasma formation. According to Gottschalk and Kleine (1976), chromosome pairing is under the control of 2 groups of genes designated as and ds which when present in recessive state, cause pairing to fail. The absence or failure of synapsis is termed as asynapsis, while the immediate separation of the homologues following normal pachytene pairing is specified as desynapsis (Gottschalk and Kaul, 1980a, b).Desynapsis has been studied in various plants like Pennisetum (Jauher et al. 1971), Zinnia Gupta, 1981), Chilli (Rao andKumar, 1983) In a mutation-breeding programme on soybean (Glycine max) through g-rays we came across with some sterile mutants. Cytogenetic analysis of these sterile mutants clearly revealed the occurrence of desynapsis in these plants. The present study is an attempt to understand the genetic behavior of sterility as well as its mechanism through cytogenetic analysis of these sterile-desynaptic mutants as our knowledge on these aspects is still very limited especially in case of soybean, although some very interesting facts have already been reported.

Spontaneous Occurrence of Structural Heterozygosity in ‘Buckwheat’ (<i>Fagopyrum acutatum</i>) from the Parvati Valley, Himachal Pradesh, India

“…Occurrence of high frequency of univalents (up to six) in 15.15% of the analysed meiocytes in the studied diploid taxon of F. acutatum could be attributed to the hybrid constitution of the genome (Stebbins and Pun 1953, Stoyanova 1970, Singhal 1982, Palakarcheva and Dorossiev 1992, Krusteva 1995, Doroszewska and Berbeć 1996, 2000, Legget 1998, Trojak-Goluch and Berbeć 2003, Kumar and Singhal 2013. However, asynapsis/desynapsis resulting into univalent chromosomes in the present case could also originate spontaneously (Kaul and Murthy 1985, Singh 2003, Bala et al 2010, Sharma et al 2010, Kumar and Singhal 2011, Ranjbar et al 2012 or be induced by various factors such as temperature, humidity, nutrients, radiations, mutagens and chemicals influencing chromosomal pairing during meiosis I (Prakken 1943, Ahloowalia 1969, Sjödin 1970, Singh et al 1977, Koduru and Rao 1981, Vishnuvardhan and Lakshmi 1987, Rao and Kumar 2003, Kumar and Rai 2006, 2007, Gulfishan et al 2010, Avijeet et al 2011. The studied individuals of this medicinal herb which grows at higher altitudes in the valley where due to low temperature conditions prevailing at a time when plants enter flowering/bud stage might have been responsible for causing synaptic irregularities in chromosomes during meiosis as has been suggested earlier in R. laetus , D. angulatus (Kumar et al ) and S. diversifolia (Kumar and Singhal 2013).…”

Induced desynaptic variation in poppy (Papaver somniferum L.)

“…Both spontaneous and induced types of desynapsis have been reported in different plant species like Pennisetum ramosum (Jauhar et al 1971), Zinnia haegena (Singh and Gupta 1981), Capsicum annum (Rao and Kumar 1983), Hordeum vulgare (Srivastava 1974, Kumar andSingh 2002), Oryza sativa (Reddi and Rao 2000), Cicer arietinum (Kumar and Sharma 2001), Anogeissussericea (Rao and Kumar 2003), Glycine max (Palmer and Horner 2000, Bione et al 2002, Kumar and Rai 2006, Corchorus fascicularis (Maity and Datta 2009). Thus, desynapsis is an important cytological phenomenon and desynaptic plants offer possibility for the production of aneuploids (Soost 1951, Burnham 1962.…”

Cytogenetical Study of Induced Desynaptic Variants in <i>Phaseolus vulgaris</i> L.

“…A mutation in the genes controlling the meiotic recombination may lead to failure or early dissolution or reduction of chiasma formation. At least one chiasmata per bivalent is essential for orderly disjunction; otherwise some homologues may migrate to the same pole and form aneuploid gametes (Kumar and Rai 2006).…”

“…The frequency of univalents formed will depend on the degree to which such mutations influence the chromosome pairing (Falistocco et al 1994). Spontaneous as well as induced desynapsis have been reported in different economical plants periodically, such as Pisum sativum (Gottschalk and Baquar 1971), Hordeum vulgare (Sharma and Reinbergs 1974), Corchorus olitorius (Basak and Paria 1980), Capsicum annum (Rao andKumar 1983, Sengupta et al 1999), Cicer arietinum (Kumar and Sharma 2001), Haplopappus gracilis (Jackson et al 2002), Glycine max (Bione et al 2002, Kumar andRai 2006), Corchorus fascicularis (Maity and Datta 2009), and Vicia faba (Bhat and Wani 2015), etc. Desynaptic plants open up new avenues for the production of aneuploid lines in breeding programmes. The desynaptic plants are used as a valuable resource for the study of male sterility in plants.…”