Glycine max Transcriptome or Gene expression

RNA-seq data from three soybean (Glycine max (L.) Merr.) fast neutron mutants were compared to the cultivar from which they are derived (cv. 'M92-220'). The three mutants include a gnarled trichome mutant (known as R55C01 or FN0175501), a high seed protein mutant (known as R15C01 or FN0171501) and a short petiole architecture mutant (known as 'Christmas tree', 6R44C72 or FN0164472). Genetic mapping of the gnarled trichome mutant using whole genome sequence-based bulked segregant analysis identified a 26.6 megabase interval on chromosome 20 that co-segregates with the phenotype. Comparative genomic hybridization analysis of the mutant indicated that the chromosome 20 interval included a small structural variant within the coding region of a soybean ortholog (Glyma.20G019300) of Arabidopsis Nck-Associated Protein 1 (NAP1), an important regulator of actin nucleation during trichome morphogenesis. Sequence analysis of the candidate allele revealed multiple rearrangements within the coding region, including two deletions (approximately 1-2 kb each), a translocation, and an inversion. Further analyses revealed that the mutated allele perfectly co-segregated with the phenotype, and a wild-type soybean NAP1 transgene functionally complemented the Arabidopsis nap1 mutant (grl-4). Additionally, mapping and exon sequencing of NAP1 in a spontaneous soybean gnarled trichome mutant (T31) identified a frame shift mutation resulting in a truncation of the coding region. These data indicate that the soybean NAP1 gene is essential for proper trichome development and that the soybean gnarled phenotype resulted from complex structural rearrangements induced by fast neutron mutagenesis at the NAP1 locus

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