BrAP2 Gene Holds Key to Improved Seed Production in Brassica

Many vegetable and oilseed crops belong to Brassica species. The seed production of these crops is limited by abnormal floral organs, especially under unfavorable abiotic conditions. Furthermore, the genetic mechanisms for abnormal floral organs remains poorly understood. The team of Yanfeng Zhang from the Hybrid Rape Research Center in China, report a novel pistil-like flower mutant of turnip (Brassica rapa).

The mutant possesses a flower where the four sepals are merged into one carpel, enveloping some abnormal stamens and a pistil, and resulting in poor seed production. This novel mutant is named sepal-carpel modification (scm). Analysis revealed that the BrAP2a gene, which specifies sepal identity, loses its function in scm mutants due to an insertion.

Expression of BrAP2b, as well as its paralog BrAP2a, rescues the sepal defective phenotype of the ap2-5 mutant of Arabidopsis. The researchers then used CRSIPR-Cas9 on oilseed rape (Brassica napus) targeting its BnAP2 gene, an ortholog of the BrAP2 genes. The resulting CRISPR mutants exhibited scm-like phenotype, proving their hypothesis.

These results suggest that the BrAP2 gene plays a key role in sepal modification. This provides a look into the mechanism underlying controlling floral organs and will be useful for genetic manipulation for the improvement of flowering and seed production of Brassica crops.

For more information, read the article in Frontiers in Plant Science.