The success of conventional breeding and selection relies heavily on available genetic variation. The depletion of genetic diversity is therefore a crucial limiting factor to next generation plant breeding, and therefore an obstacle to feed the increasing world. While spontaneous mutation adds new alleles to the gene pool at a slow rate, radiation- and mutagen-induced mutations rapidly trigger structural and nucleotide changes in the genome. It is commonly accepted that induced mutagenesis generates random alteration on DNA sequences and structural changes at genome-wide scale. However, new evidence show that radiation mutagenesis generates specific local lesions and structural changes in the genome. For instance, next generation sequencing revealed that irradiation generates high density of single nucleotide variation of which over 80% is duplicated with spontaneous variation. In addition, selection under stresses may generate more specific gain/lost-of-function mutants which carry specific genomic changes and allelic variation similar to what can be found in natural genetic variation. What are the exact mechanisms allowing the rapid generation of genetic variation remain unclear. Identifying those will empower breeders to rapidly develop better plant varieties to cope with the imminent climate changes and respond to specific nutritional needs of the populations.

In this Research Topic, research communities are welcome to provide more evidence on mutagen-induced genomic and phenotypic variation in different plant species. Studies focusing on identifying the genetic mechanisms, pathways, and mutagenic conditions controlling new mutant alleles generation are particularly welcome. Manuscripts aimed at discussing - or at presenting new data about - maximization of genetic diversity to improve functional genomics and mutation breeding will also be considered.

Keywords: induced mutagenesis, allelic change, genetic diversity, mutation breeding, functional genomics

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