Characterization of <i>SHATTERPROOF</i> Homoeologs and CRISPR-Cas9-Mediated Genome Editing Enhances Pod-Shattering Resistance in <i>Brassica napus</i> L.

Abstract

<i>Brassica napus</i> is the most important oil crop plant for edible oil and renewable energy source worldwide. Yield loss caused by pod shattering is a main problem during <i>B. napus</i> harvest. In this study, six <i>BnSHP1</i> and two <i>BnSHP2</i> homoeologs were targeted by the CRISPR (clustered regularly interspaced short palindromic repeats)-Cas9 (CRISPR-associated protein 9) genome editing system and multiple <i>SHP1</i> and <i>SHP2</i> mutated lines were identified for evaluating the contribution for pod-shattering resistance. Our data suggest that <i>BnSHP1A09</i> is probably a promising homoeolog for controlling lignin contents at dehiscence zone. Simultaneous mutation of <i>BnSHP1A09/C04-B/A04</i> and <i>BnSHP2A05/C04-A</i> exhibited reduced lignified layer and separation layer adjacent to valves and replum. The pod-shattering resistance index (SRI) subsequently increased to 0.31 in five homoeolog mutation lines compared with the wild type (SRI = 0.036), which provide the theoretical basis for breeding of commercial pod-shattering resistance variety.