Frequent generation of mutants with coincidental changes in multiple traits via ion-beam irradiation in soybean

Abstract

Ion beams are powerful mutagens that can induce novel mutants in plants. We previously established a system for producing a mutant population of soybean via ion-beam irradiation, isolated plants that had chlorophyll deficiency, and maintained their progeny via self-fertilization. Here we report the characterization of the progeny plants in terms of chlorophyll content, flowering time and isoflavone content in seeds. Chlorophyll deficiency in the leaf tissues was linked with reduced levels of isoflavones, the major flavonoid compounds accumulated in soybean seeds, which suggested the involvement of metabolic changes associated with the chlorophyll deficiency. Intriguingly, flowering time was frequently altered in plants that had a reduced level of chlorophyll in the leaf tissues. Plant lines that flowered either earlier or later than the wild-type plants were detected. The observed coincidental changes were presumed to be attributable to the following origins: structural changes of DNA segments leading to the loss of multiple gene functions, or indirect effects of mutations that affect one of these traits, which were manifested as phenotypic changes in the background of the duplicated composition of the soybean genome.

Effects of Carbon Ion Beam Irradiation on Phenotypic Variations and Biochemical Parameters in Early Generations of Soybean Plants

“…Changes in DNA base and ribose, strand breaks, cross-linking with proteins and a higher mutation rate were also reported [16][17][18]. Furthermore, many novel mutants, which are barely identifiable by other mutagens have been obtained by CIBR, such as pink, red and yellow petals in carnations, the number of petals, flower size, shape and color mutants in roses, complex and striped color mutants in chrysanthemums [19] and multifarious compound leaves mutants and chlorophyll deficiency mutants in soybean [20]. Though phenotype variation is the most common method for screening mutants, many traits are not visually observed and thus cannot easily be screened out.…”

A Soybean Deletion Mutant That Moderates the Repression of Flowering by Cool Temperatures

“…We selected a new early-flowering mutant (N2-ef1) from a mutant population of Nourin No. 2 (N2) generated by ion-beam irradiation (Arase et al, 2011), from which several mutants with altered flowering have been selected and characterized (Mikuriya et al, 2017). We crossed N2-ef1 with the early-flowering cultivar "Tokachi Nagaha" (TN) in place of N2 to facilitate mapping of the mutant with simple sequence repeat (SSR) markers.…”

“…We previously selected and characterized mutants with altered flowering in the mutant population of Nourin No. 2 generated by ion-beam irradiation (Arase et al, 2011;Mikuriya et al, 2017). All of the mutants had yellowish leaves with reduced chlorophyll contents, and also showed promoted or delayed flowering.…”

“…A number of mutant lines with altered flowering have been selected from the same mutant population, but most of these lines had yellowish leaves with reduced chlorophyll contents (Mikuriya et al, 2017). The mutant N2-ef1 and its derived lines, however, had no phenotypic aberration in plant architecture or growth, even though 11 genes were deleted.…”

Irradiation with carbon ion beams affects soybean nutritional quality in early generations

“…It has also been reported that irradiation of grain cereals and leguminous crops seeds leads to increased protein content and higher carbohydrate and vitamin levels ( Jan et al, 2012 ). Mikuriya et al (2017) demonstrated that the populations mutagenized by carbon ion beam irradiation exhibited lower isoflavone concentration in soybean seeds, which was closely related to the reduction of leaf chlorophyll concentration. The increased concentration of genistin, genistein, daidzin and glycitein, but decreased concentration of glycitein and daidzein in soybean seedlings were found by laser irradiation ( Jin et al, 2011 ).…”