Study Explains Auxin's Role in Rice Root Proliferation

A well-developed root system in rice (Oryza sativa) and other crops can ensure efficient absorption of nutrients and water. Auxin is a vital regulator for root development, however, the mechanisms by which auxin controls root development in rice are not fully understood. Researchers from the Huazhong Agricultural University in China, led by Tao Zhang, aim to explain these mechanisms.

The team found that overexpression of a YUC gene, which is vital for auxin synthesis, causes massive proliferation of crown roots. On the other hand, the disruption of the TAA1 gene, which functions upstream of the YUC genes, greatly reduces rice crown root development. Further analysis found that the crown root proliferation from YUC overexpression lines required the transcription factor WOX11.

The team also developed taa1 mutants via CRISPR-Cas9. These mutants exhibited crown rootless phenotype, which was partially rescued by overexpression of the transcription factor WOX11. WOX11 expression was also found to be induced in YUC overexpression lines, but is repressed in the taa1 mutants.

These results indicate that auxin synthesized by the TAA/YUC pathway is sufficient for crown root development in rice. Auxin activates WOX11 transcription, which drives root initiation and development. This establishes the YUC-Auxin-WOX11 complex for crown root development in rice.

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