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The fertility segregations of F1, F2, BCF1 descended from crosses between PSGMR and japonica varieties, and F1's anther cultured homozygous diploid pollen plant populations (H2) were studied to reveal the genetic mechanism of photoperiod sensitive genic male sterility in PSGMR under natural daylight length at Shanghai. Rate of bagged seed-setting was used as an indicator of fertility. Fifteen F1 showed...
A plant regeneration system from rice protoplasts using calli derived from mature embryos was established for the two Brazilian modern rice cultivars IAC-201 and IAC-165. After 30 to 40 days of in vitro culture it was possible to obtain on average 6 million protoplasts per gram of callus. Microscopic selection of embryogenic calli was a key step for protoplast isolation. The production of embryogenic...
Magnitudes of genetic variation within each of major varietal groups of cultivated rice were surveyed in terms of isozyme polymorphism and allelic differentiation of hybrid sterility loci, both of which are considered to have litt le selective value. Allelic differences for 20 isozyme loci were examined in a total of 337 accessions, including Indica and Japonica rices. Aus cultivars from India, Javanica...
The morphology and cytology of selected hybrid swarms of wild and cultivated rices were studied following natural hybridization between the native species Oryza rufipogon Griff and exotic species Oryza sativa L. (var. Thaothabi and Moirangphoe). Similar studies were also conducted on populations developed through artificial hybridization of those two species. The morphological variation in plant height,...
Hybrid sterility of the cross between Silewah, an Indonesian native variety and Hayakogane, a Hokkaido rice variety in Japan was confirmed to be caused by anther indehiscence, based on a lot of spikelets with fewer numbers than 3 of dehiscent anthers and fewer numbers of pollens poured onto stigma per spikelet in Silewah/Hayakogane F1. In Silewah/Hayakogane//Hayakogane BC1F1, spikelet fertility was...
The mode of inheritance of five semidwarf (SD) mutants and allelic relationship with DGWG (sd1) locus was studied. The five SD mutants viz., Basmati 370 (SD1), Basmati 370 (SD2), Basmati 370 (SD3), TCA 2 (SD) and TCA P2-5 (SD) when crossed with their tall parents exhibited monogenic inheritance of 3 tall: 1 semidwarf in the F2 progenies. The SD mutants were also crossed with semidwarf varieties (DGWG...
Recent genetic analyses on heading-time of rice indicated that almost all the well-adapted varieties in the temperate zone carry a strong photoperiod-sensitivity gene E1, a dominant allele of E1 locus. In order to identify the chromosome on which E1 is located, a trisomic analysis was made using two primary trisomic series originating from the japonica varieties, Nipponbare and Kinmaze, respectively...
Following anther culture of various F1 hybrids of indica restorer (R) lines/wide compatible varieties (WCVs) and japonica R lines/WCVs, the homozygous diploid plants (2n) generated were test-crossed with indica WA type cytoplasmic-genetic male sterile (CMS) line Zhanshan 97A (WA), indica testers Nanjing 11 and Nante, japonica BT CMS line Hanfeng A (BT), and japonica testers Balilla and Akihikari to...
In the past, utilisation of African cultivated rice, Oryza glaberrima, in O. sativa breeding was hampered by high sterility in interspecific F1 and in early progenies. Recent development of mapped molecular markers provides the opportunity to rationalise and to monitor introgressions between the two cultivated rice species. Development of such introgressed lines through interspecific hybridisation...
Embryo-derived calli of four rice varieties cultivated at high altitude in Burundi — Facagro 57, Facagro 76, Kirundo 3 and Kirundo 9 — were submitted to different temperature regimes. The percentage of regenerating calli greatly varied depending on variety, length of culture and callus temperature treatment. The reduction of regeneration percentages induced by low temperature was more pronounced in...
Southern United States long grain rice (Oryza sativa L.) is a unique market type characterized by intermediate amylose content, gelatinization temperature, and amylograph viscosity profile characteristics. Rice breeders sometimes use long grain germplasm with differing amylograph viscosity profiles. The inheritance of rice amylograph viscosity profiles has not been ascertained and, thus, was the objective...
A selection procedure is described that isolated Al-resistant individuals from a sensitive rice (Oryza sativa L.) genotype. Somaclonal variation was used as the only source of variability and selection pressures were applied at both callus and regenerated plant levels. When 10 week-old, embryo-derived calli were submitted to different Al stresses for a period of 20 weeks. After this in vitro stress...
Hybrid varieties developed by making use of the wild abortive cytoplasmic male sterility system account for 90% of hybrid rice produced. Previous inheritance studies have established that the fertility restoration in this system is controlled by two major loci, but the chromosomal locations of the fertility restorer (Rf) loci have yet to be resolved. In this study we determined the genomic locations...
Two rice ecotypes, the so-called lowland and upland populations, which carry different isozyme genotypes mostly at a single locus, are cultivated in Japan. The aim of this study was to examine the origin and the mechanism for keeping these genetic differences. The upland population is cultivated in upland fields and carries a different allele for a particular isozyme gene, Pgd-1, which has never been...
Moderate to high heterosis for yield and ten related characters was studied in 45 crosses involving six indica (I) and four tropical japonica (J) varieties of rice under three (E1-optimum sowing and high fertility, E2-both optimum sowing and fertility and E3- late sowing and high fertility) environments. Trends of magnitude of heterosis for grain yield and plant height were I/J > I/I > J/J and...
The rice (Oryza sativa L.) crop in Arkansas is seeded from late March through early June each year. Farmers need new rice cultivars that not only produce both high rough rice yields and high head rice across this range of seeding dates but do so consistently. Thus, a seeding date study was conducted during 1994 and 1995 at Stuttgart, Arkansas, to study seeding date effects on rough rice yield and...
A simple and efficient technique for in vitro unpollinated ovary culture in rice which is also applicable for indica genotypes was developed for breeding and genetic studies. Sampling explants at the auricle distance of 7–12 cm between the two uppermost leaves of a tiller, providing a chilling pretreatment and ovaries with 1/3 of the hulls intact gave optimum response to culture. For callus induction...
A genic male-sterility gene newly induced by chemical mutagenesis, tentatively designated as ms-h(t), was located on the molecular map of rice and tested for its effect on chalky endosperm. Bulked segregant analysis was used to determine the chromosomal location of the ms-h(t) locus by screening four to five RFLP markers per chromosome. After confirming that the gene was located on chromosome 9, twenty-four...
Plants derived from unpollinated ovary culture of ten rice genotypes showed significant variability in agro-morphological characteristics. The ovary-derived plant (H1) populations were completely haploid, doubled haploid or haploid-doubled haploid mixture. Haploids had very drastic reduction in plant height, panicle length, grain length, breadth and number and spikelet fertility (0.0%–2.1%). Doubled...
Ten microsatellite loci were analysed for 43 cultivars or breeding lines of rice. Polymorphism-Information-Content values ranged from 0.62 to 0.92. The microsatellite markers were found to be useful for cultivar identification and assessment of genetic relationships. Most of the cultivars could be uniquely identified by at least one microsatellite marker. Genetic heterogeneity was detected within...
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