EMS-induced point mutations in ALCATRAZ homoeologs increase silique shatter resistance of oilseed rape (Brassica napus)

In Arabidopsis ( Arabidopsis thaliana ), the transcription factor ALCATRAZ (ALC) is involved in the control of silique tissue identity, ensuring the establishment of a separation layer that contributes to the fragility of the dry fruit. The silique structure is retained in the related crop species oilseed rape ( Brassica napus ), in which it causes yield losses due to seed shedding. A more robust rapeseed silique through Bnalc loss-of-function mutations was hypothesized. We demonstrated the increased silique shatter resistance of oilseed rape through Cas9-induced targeted Bnalc mutations in a previous work. However, the effect was masked by the high shatter resistance of the transformed cultivar itself. In the present study, we used a rapeseed genotype with low shattering resistance and followed an approach of random mutagenesis. We identified 23 Bnalc mutants by TILLING of an EMS-mutagenized ‘Express’ population. By measuring tensile forces necessary to disrupt mature siliques, we determined a double mutant with significantly increased shatter resistance. This mutant can readily be introduced into breeding programs.