Physiological status of plant tissue affects the frequency and types of mutations induced by carbon-ion irradiation in Arabidopsis

Yoshihiro Hase,Katsuya Satoh,Yutaka Oono,Satoshi Kitamura

doi:10.1038/s41598-018-19278-1

Yoshihiro Hase, Katsuya Satoh + Show 2 more

Open Access

https://doi.org/10.1038/s41598-018-19278-1

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Abstract

Ionizing radiation including heavy-ion beams has been widely used in mutation breeding. Dry seeds, seedlings, and cultured tissues are often used for mutagenesis; however, little is known about the differences in induced mutations among them. Here, we examined the characteristics of mutations using randomly chosen Arabidopsis M2 plants derived from dry seeds and seedlings irradiated with carbon ions. The mutation frequency was 1.4–1.9 times higher in dry-seed irradiation than in seedling irradiation. This difference was mainly due to the three-times higher frequency of insertions and deletions (InDels) in dry-seed irradiation than in seedling irradiation. This difference increased the proportion of mutations predicted to affect gene function among all mutations identified by whole genome re-sequencing. Our results demonstrate that the physiological status of plant tissue greatly affects the characteristics of mutations induced by ionizing radiation, and that dry seeds are more suitable materials than seedlings for inducing loss-of-function mutations. The results also showed that single base deletions often occurred in homopolymeric sequences, while InDels larger than 2–3 bp often occurred in or near polynucleotide-repeat or microhomologous sequences. Interestingly, microhomology was less commonly found around large deletions (≥50 bp), suggesting that the rejoining process differs depending on the deletion size.

Highlights

Mutagenesis with heavy-ion beams, which are characterized by their high linear energy transfer (LET), is an effective means to generate new plant varieties, and there is increasing evidence that ion beams induce mutations more efficiently than do gamma-rays or X-rays[1,2]
This suggests that the shoot meristem of the plants derived from irradiated dry seeds contains more deleterious mutations, which lead to abnormal gametogenesis and embryonic lethality, compared with plants derived from seedlings irradiated at the same effective dose
We demonstrated that the size of the mutant sector increased as the LET of ionizing radiation increased in Arabidopsis[4,5]

Summary

Introduction

Mutagenesis with heavy-ion beams, which are characterized by their high linear energy transfer (LET), is an effective means to generate new plant varieties, and there is increasing evidence that ion beams induce mutations more efficiently than do gamma-rays or X-rays[1,2]. Compared with mock-treated petunia seedlings, those treated with sucrose (to stimulate colour pigment biosynthesis) yielded a higher frequency of flower-colour mutants after ion beam irradiation, the frequency of chlorophyll mutants was unaffected[13]. These results strongly suggest that physiological status of plant tissue is an important factor in efficient mutagenesis. Physiological status of plant tissue on the frequency and types of mutations induced by carbon ion irradiation in Arabidopsis. This study provides strong evidence for the first time that the physiological status of plant tissue greatly affects the frequency and types of mutations at the molecular level

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Conclusion