[en] Several herbicide-tolerant crops have been developed and commercialized from herbicide-tolerant mutants obtained through chemical mutagenesis followed by herbicide selection or direct herbicide selection of spontaneous mutations. All mutations used in commercial herbicide-tolerant crops are derived from a single nucleotide substitution of genes that encode enzymes or proteins targeted by herbicides. The alleles of all commercial herbicide-tolerant mutations are incompletely-dominant except for the triazine-tolerant mutation. (author)

[en] A novel Arabidopsis EMS mutant population was produced aiming at identifying until now unknown meiotic mutants. The M₂ EMS mutant families were first screened for their reduced fertility. These plants with a reduced fertility were subjected to a second screening at the cytological level. Plants with abnormal meiosis, namely abnormal chromosome segregation and chromosome fragmentation were selected for further characterization and SNP mutation mapping. So far, 232 sterile and semi-sterile M₂ candidates have been identified in the fertility screen, of which 110 sterile mutants were further analyzed at the cellular level; 15 of these have been analysed at the cytological level. Mapping has been carried out. (author)

[en] Induced mutagenesis work was conducted from 1971 to July 2007, using both physical and chemical mutagens for improvement of a wide range of crops viz. vegetables, medicinal, pulse, oil-bearing, and ornamental crops. All classical and advanced methods were extensively used for the success of induced mutagenesis for the development of new and novel cultivars of economic importance. Being deeply engaged for the last 30 years on improvement of ornamentals through Gamma-ray induced mutagenesis, I have produced a large number of new and promising varieties in different ornamentals. A good number of ornamental mutant varieties have already been commercialized. A novel technique has been developed for management of floral chimeric sector in chrysanthemum through direct regeneration of mutated individual florets. A series of in vitro experiments were conducted and solid mutants developed through direct regeneration. In vitro mutagenesis has been successfully used for development of a salt-resistant strain in chrysanthemum, supported by biochemical analysis and field trials. (author)

[en] A large number of new somatic flower color/type mutants have been evolved by induced mutations in different ornamental plants. Few reports are available on the systematic work being done on the comparative analysis of the original and mutant cultivars. This paper reports the result of comparative analysis on cyto-palynological, biochemical and molecular characters of original and mutant cultivars for a better understanding of the exact mechanism involved in the origin and evolution of flower color mutations. Cultivar identification and cultivar relatedness are important issues for horticultural breeders. Proper characterization and identification of new mutant cultivars is extremely important to protect plant breeder's rights for commercial exploitation. (author)

[en] Root architecture influences the acquisition of mineral elements required by plants. In general, plants with a greater root/shoot biomass quotient and a more extensive root system acquire mineral elements most effectively. In barley (Hordeum vulgare L.) induced mutation has produced commercial cultivars with greater root system size, and genotypes with greater root spread, longer roots and roots with denser root hairs. Work is in progress investigating whether these phenotypes improve the acquisition of mineral elements and, thereby plant growth and grain yield. (author)

[en] Starch debranching enzymes in plants are divided into two groups based on their ability to hydrolyze different substrates. The first group, pullulanases, hydrolyze α-1,6-glucosidic linkages in substrates such as pullulan, amylopectin and glycogen. The second group of debranching enzymes, isoamylases, hydrolyze glycogen and amylopectin and are not active on pullulan. Three isoforms of isoamylase and a pullulanase have been isolated from a cDNA library of Pisum sativum. These isoamylases have been characterized following their heterologous expression in E. coli. Based on the DNA sequence that encodes these debranching enzymes, a specific mutagenesis targeting these enzymes will be attempted. The technique involves the homologous recombination of DNA mediated by zinc-finger endonucleases. Vectors will be constructed to include a fragment that will modify these genes. Using this technique, it is hoped that null mutants for each enzyme will be created and the exact role of these enzymes for the synthesis and degradation of starch in plants will be elucidated. (author)

[en] The rice material Hangai-1 that is studied here is a stable dwarf mutant obtained by space mutation of rice cultivar Texianzhan 13(indica). Genetic analysis showed that its dwarf trait was controlled by two recessive semi-dwarf genes, sd1 and a new semi-dwarf gene, named iga-1. This new semi-dwarf gene iga-1 was located between microsatellite markers RM6645 and RM3837 on chromosome 5, the genetic distances between them were 0. 07cM and 1.21cM, respectively. The iga-1 gene is possibly a multiple allele to the d-1 gene. The semi-dwarf mutant with the new semi-dwarf gene iga-1 was found to be insensitive to gibberellin 3(GA₃). (author)

[en] A large spectrum of mutations was observed as a result of winter wheat T. aestivum L. irradiation for two consecutive vegetative seasons (during 1986-87) in the fields close to the ruined reactor of the Chernobyl Nuclear Power Station. Mutants taken from the different generations (L147/91, BC 47 square head, dwarf 20104/89) were used for development of the varieties Lybid, Yasochka and Tsarivna to utilize traits from the mutants such as hardiness, drought tolerance, disease and lodging resistance and bread quality. These varieties were included in the State Variety Register of Ukraine, while another one, Lisova Pisnya is included in the list of perspective varieties. (author)

[en] Two new high-quality and early-yielding indica rice cultivars, Jiahezaozhan and Jiafuzhan, have been developed, certified, and cultivated by farmers in the provinces of Southern China. These new rice varieties were created by a new mutation breeding technique in which mature rice pollen irradiated with Gamma (γ)-ray was used to produce parents for crossing. The optimal dose for the irradiation was approximately 46Gy. The cumulative effects of the mutations increased in advanced generations and most of the mutant traits became stable in the fifth generation. These results showed that the mutations generated by Gamma-radiation on mature rice pollen were largely of quantitative trait loci. (author)

[en] Physical availability and economic accessibility of food are the most important criteria of food security. Induced mutations have played a great role in increasing world food security, since new food crop varieties embedded with various induced mutations have contributed to the significant increase of crop production at locations people could directly access. In this paper, the worldwide use of new varieties, derived directly or indirectly from induced mutants, was reviewed. Some highlights are: rice in China, Thailand, Vietnam, and the USA; barley in European countries and Peru, durum wheat in Bulgaria and Italy, wheat in China, soybean in China and Vietnam, as well as other food legumes in India and Pakistan. An exact estimate of the area covered by commercially released mutant cultivars in a large number of countries is not readily available, but the limited information gathered clearly indicates that they have played a very significant role in solving food and nutritional security problems in many countries. (author)