Genetic control of meiosis in rice Oryza sativa L. II. Cytogenetical analyses of desynaptic mutants.

Abstract

Eleven desynaptic mutants of Oryza sativa L. were cytogenetically investigated.Mutants were induced by the treatment of fertilized egg cells with N-methyl-N-nitrosourea.Normal chromosome pairing occurred at pachytene in all mutants. Various numbers of univalents appeared at diakinesis and metaphase I in the mutants. The reduction of the mean chiasma frequency per bivalent as well as per cell were recognized in all mutants. The lower the mean chiasma frequency, the lower the mean bivalent frequency. The results of gene analyses indicate that each of the desynaptic mutants is governed by a single recessive gene and that at least 10 loci are represented.

Effect of Physical and Chemical Mutagens on Chiasma Frequency inLycopersicon EsculentumMill.

“…The role of mutated genes in creating the change in chiasma formation has been reported in desynaptic mutants by GoTTSCHALK and VILLAOBAS-PETRINI (1965) in peas, KITADA andOMURA (1983) in rice andSADANANDAM et al (1981) in Capsicum. According to STEIN and HoTTA (1969) the DNA and proteins have an important role on crossingover.…”

Meiosis-Driven Genome Variation in Plants

“…Asynaptic and desynaptic mutants have been documented in many plant species [see 108 for a review]. Some of the mutants have been extensively characterized in major crop and model species, including wheat [109], maize [see 110 for a review, 111], rice [112][113][114][115], tomato (L. esculentum) [116], soybean [117], and Arabidopsis thaliana [118][119][120][121][122]. Asynapsis and desynapsis are usually conditioned by single recessive genes, such as st2, st3, and st8 for asynapsis and st4 and st5 for desynapsis in soybean [117,123,124], dy and dsy1 for desynapsis and phs1 for poor homologous synapsis in maize [111,125], and spo11-1-3, dsy1, mpa1, and asy1 in Arabidopsis thaliana [118][119][120][121][122].…”

Cytogenetical studies on African rice, Oryza glaberrima Steud. 1. Colchicine-induced autotetraploid.

“…In autotetraploids of 0, sativa, the random pairing among four homologous chromosomes was proved from the fact that the F2 segregation ratios for various monogenic characters gave a good fit to the ratios expected from random pairing of homologous chromosomes or chromatids (Morinaga 1951;Oka 1955). Moreover, in the diploid species of Oryza, the number of chiasmata per bivalent was less than 2 (Chu et al 1969 ;Nayar 1973;Kitada and Omura 1983). On top of that, the number of chiasmata per bivalent in the autotetraploid of glaberrima in this experiment was also less than 2 because trivalents and univalents were observed.…”