Rice seeds, after space flight and low dose heavy ion radiation treatment were cultured on ground.
Leaves of the mature plants were obtained for examination of genomic/epigenomic mutations by using
amplified fragment length polymorphism (AFLP) and methylation sensitive amplification polymorphism
(MSAP) method, respectively. The mutation sites were identified by fragment recovery and sequencing.
The heritability of the mutations was detected in the next generation. Results showed that both space
flight and low dose heavy ion radiation can induce significant alterations on rice genome and epigenome
(P < 0.05). For both genetic and epigenetic assays, while there was no significant difference in mutation
rates and their ability to be inherited to the next generation, the site of mutations differed between
the space flight and radiation treated groups. More than 50% of the mutation sites were shared by
two radiation treated groups, radiated with different LET value and dose, while only about 20% of the
mutation sites were shared by space flight group and radiation treated group. Moreover, in space flight
group, we found that DNA methylation changes were more prone to occur on CNG sequence than CG
sequence. Sequencing results proved that both space flight and heavy ion radiation induced mutations
were widely spread on rice genome including coding region and repeated region. Our study described and
compared the characters of space flight and low dose heavy ion radiation induced genomic/epigenomic
mutations. Our data revealed the mechanisms of application of space environment for mutagenesis and
crop breeding. Furthermore, this work implicated that the nature of mutations induced under space flight
conditions may involve factors beyond ion radiation.