Cytogenetics of synaptic mutants in higher plants

That meiosis is conditioned by a large number of genes majority of which are present in a dominant state, is evidenced by the detection of numerous monogenic recessive mutant genes which affect the premeiotic, meiotic and post-meiotic course of events. These genes are site- and stage-specific, and a few are sex specific. Of these, the most prevalent are the mutant genes affecting male meiosis and causing male sterility (ms genes) and those inhibiting synapsis and chiasma formation (synaptic genes) and leading to gametic sterility. Majority of the mutant genes affect the entire chromosomal complement but a few influence only specific chromosomes of a complement so that the chromosomes behave differentially within a genome of the same species. Some mutant genes alter chromosome form and function, others modify integrity, degree of spiralization, movement and migration of chromosomes. Their cytogenetic behaviour, genetic significance and breeding utility are described and discussed.

Mutant genes affecting higher plant meiosis.

Samples of traditional sorghum beer Ikigage was collected in the southern province of Rwanda and analyzed for microbiological and physico-chemical contents.Ikigage contained total aerobic mesophilic bacteria (33.55 x 106 cfu/ml), yeast (10.15 x 106 cfu/ml), lactic acid bacteria (35.35 x 104 cfu/ml), moulds (4.12 x 104cfu/ml), E. coli (21.90 x 103 cfu/ml), fecal streptococci (22.50 x 103 cfu/ml),Staphylococcus aureus (16.02 x 103 cfu/ml), total coliform (32.30 x 103 cfu/ml),  ethanol, soluble protein, reducing sugars, total acidity, pH and Brix were 2.2% (v/v), 9.2 g/l, 2.3, 1.7%, 3.9 and 11.5 bx, respectively. The yeast was identified by API 20 C test and confirmed by PCR-Sequencing of ITS-5.8S region of rDNA. Seventy yeasts isolated in the samples were found to belong to either Saccharomyces cerevisae, Candida inconspicua, Issatchenkia orientalis, Candida magnolia andCandida humilis. Lactic acid bacteria were identified using the API 50 CHL system. Ten different isolates of lactic acid bacteria belonged exclusively to the genus Lactobacillus: Lactobacillus fermentum, Lactobacillus buchneri, and Lactobacillussp. The micro-organisms of fecal origin are from the water and the operations post-fermentation process. The presence of potential pathogens emphasizes the importance of developing starter cultures with GRAS status for commercialization of ikigage.

	 

	Key words: Sorghum beer, Ikigage, alcohol fermentation, microbiology, physico-chemistry.

https://www.ajol.info/index.php/ajb/article/download/82637/72796

Microbiological and physico-chemical characteristic of Rwandese traditional beer " Ikigage "

Cytoplasmic male sterility was found in the progenies of intraspecific cross in oil seed rape. Sometimes partially male sterility segregated in the progenies and its expression seemed to depend upon environmental conditions. The degeneration of anther occurred between the stages of carpel differentiation III and male archesporial cell differentiation I. Out of 32 Japanese varieties and three lines tested, four fertility restoring, nine partially restoring and three non-restoring varieties to the male sterile lines were found. High seed yield obtained from open-pollinated male sterile lines may promise to be sufficient for production of hybrid seed.

Cytoplasmic Male Sterility in Oil Seed Rape. Brassica napus L., and its Utilization to Breeding.

Summary Isolation of seven different types of trisomics was possible in the advanced generations of an induced trisomic recovered earlier in grass pea cultivar BioR-231. The trisomic plants were phenotypically distinguishable from the diploid mother cultivar (2n� 14) by their contrasting morphological characteristics and cytologically by the presence of an extra chromosome (2n� 1� 15). Variations in several morphological traits were distinctive and stable in different trisomic plants during succeeding generations. Among the phenotypic manifestations, modifications in leaflet morphology, stipule character and seed coat colour were specific for each of the seven types of trisomics. The different trisomics could be distinguished instantly from one another by the characteristic shape, number, position and orientation of leaflets as well as stipules. Since leaflet character was specific and distinctly visible at the very seedling stage it could be used conveniently as a marker character for identification and classification of seven trisomics. Moreover, apical modification of leaflet, complete absence or occurrence of stipule in different forms and variations in floral morphology were also conspicuously different in different types. The extra chromosome appeared as univalent or in trivalent association and the trivalents occurring only in linear or frying pan or Y shaped configuration characterized all of the 7 types as primary types. Pollen sterility and reduced seed yield in these trisomic types might be the consequences of unequal separation, formation of laggard and anaphase bridge.

Seven Different Primary Trisomics in Grass Pea (Lathyrus sativus L.). I. Cytogenetic Characterisation

Cytological effects of three growth substances namely, Gibberellic acid (GA), Indole-butyric acid (IBA), and 2, 4-Dichlorophenoxyacetic acid (2, 4-D) were studied on root tip mitosis of Vicia faba treated with 10 and 50 ppm concentrations and 3, 6 and 12 hours durations. GA enhanced cell division while 2, 4-D and IBA inhibited it and were more toxic than GA. Main effects at chromosomal level were chromosome breakage, bridge formation, C-mitosis, micronuclei formation, stickiness and chromosome condensation.

Effects of Some Growth Substances on Mitosis

Cyto-morphological studies were conducted on male sterility in yellow and brown sarson. In the post-meiotic stages, the tapetum did not seem to function as a nutritive layer in yellow sarson as it persisted long after degeneration of tetrads. The non-dehiscence of anthers in brown sarson appeared to be due to the presence of large, irregular cells of anther wall in the form of a thick, compact layer. Meiotic studies on these two types of male sterility did not show any abnormality

Cyto-morphological Studies on Male Sterility in Brassica campestris L

Studies on Meiotic System of some Barley Mutants Induced through Alkylating Agents

A Note on Translocation-trisomic Plant From Gamma-irradiated Barley

The trisomic plant isolated from gamma-irradiated barley material was pheno-typically different from the normal diploid. The leaves of the trisome were narrow, margins rolled and light green in colour. Ear heads were also short, narrow and irregular. Ovule sterility (42.88 per cent) was relatively higher than pollen sterility (23.47 per cent).Cytological examination at metaphase I revealed 6II+1III, 7II, +1I and 6II+3I. The trivalents were chains of 3 and V, Y, frying pan and Q shaped indicating it to be a primary trisomic.The trisome was crossed with a set of translocation homozygotes and the cytology of the F1 hybrids was studied. This revealed that it was a trisomic for chromosome 3. However, the present trisomic looked different from the pale trisomic for chromosome 3 described by Tsuchiya in 2-rowed barley.Trisomics occurred more frequently in the progeny of smaller seeds of tri-somic plants. Transmission rate of the extra chromosome through ovule was high while it was nil through pollen.

https://www.jstage.jst.go.jp/article/cytologia1929/38/1/38_1_91/_pdf

K. Das

Papers

Effects of Some Growth Substances on Mitosis

Cyto-morphological Studies on Male Sterility in Brassica campestris L

Studies on Meiotic System of some Barley Mutants Induced through Alkylating Agents

A Note on Translocation-trisomic Plant From Gamma-irradiated Barley

A Primary Trisomic for Chromosome 4 in a Six-Rowed Barley