APETALA2 Gene Key to Improving Seed Production in Brassica Species

Several vegetable and oilseed crops belong to Brassica species. The seed production of these crops is often affected by abnormal flowers, especially under the unfavorable abiotic conditions. However, the molecular reasons for these abnormal floral organs remain unknown.

A team led by Yanfeng Zhang from the Hybrid Rapeseed Research Center in China aims to shed light on this by studying a flower mutant of turnip (Brassica rapa). In the flower of this mutant, named sepal-carpel modification (scm), the four sepals are modified to one merged carpel that look like a ring, enveloping abnormal stamens and a pistil, and resulting in poor seed production.

DNA analysis of the mutant showed that the BrAP2a gene, the ortholog of Arabidopsis APETALA2 (AP2) that specifies sepal identity, lost its function in the scm mutant due to an insertion. Furthermore, the CRISPR-Cas9-knockout of the two BnAP2 genes, BrAP2a, and its ortholog BrAP2b, in oilseed rape (Brassica napus) resulted in scm-like phenotype, suggesting that BrAP2 plays a key role in sepal modification.

These findings could provide an insight into the morphological modification of floral organs and will be useful for improvement of seed production of Brassica crops.

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