Characterization of a semidominant dwarfing PROCERA allele identified in a screen for CRISPR/Cas9-induced suppressors of loss-of-function alleles.

Gibberellin (GA) is a plant hormone that regulates important growth processes including germination, flowering, and fruit development. DELLA proteins inhibit GA responses. GA signaling increases through GA triggered destruction of the DELLA protein. Several mutants with reduced stature due to mutations that stabilize the DELLA protein are known. Many of these mutations cause deletions within the DELLA domain. Here we report several new dwarfing alleles of the tomato DELLA protein, PROCERA, generated using the CRISPR/Cas9 system to create intragenic suppressors of two pro loss-of-function alleles. The new mutations affected the DELLA domain and one of the alleles, pro GF8 , which has a 12 amino acid insertion and 2 amino acid substitution affecting the LExLE motif of DELLA domain was further characterized. This allele is semidominant. PRO/pro GF8 plants are extreme dwarfs and do not respond to exogenous GA3 . However, a minor response to exogenous GA3 was found when it was applied together with the GA biosynthesis inhibitor paclobutrazol. Germination of PRO/pro GF8 seeds was delayed and pro GF8 /proGF8 seeds did not germinate without scarification. This article is protected by copyright. All rights reserved.