Through combined high-resolution image-based phenotyping with functional mapping and genome prediction, a new research conducted at the Australia Plant Phenomics Facility (APPF) provides insights into the complex genetic architecture and molecular mechanisms underlying early shoot growth dynamics in rice.

The timing of developmental ‘triggers' or switches that initiate tiller formation and rapid exponential growth in rice are a critical component of early vigor trait which is important in aerobic rice environments. However, the search for the switch that initiates this growth has proven challenging due to the complex genetic basis and large genotype-by-environment effect, and the difficulty in accurately measuring shoot growth for large populations.

The APPF team led by PhD student Malachy Campbell phenotyped a panel of ~360 diverse rice accessions throughout the vegetative stage (11-44 day old plants) at APPF. A mathematical equation was used to describe temporal growth trajectories of each accession. Regions of the genome that may regulate early vigor were inferred using genome-wide association (GWA) mapping. Many loci with small effects on shoot growth trajectories were identified, indicating that many genes contribute to this trait. GWA, together with RNA sequencing identified a gibberellic acid (GA) catabolic gene, OsGA2ox7, which could be influencing GA levels to regulate vigor in the early tillering stage.

For more details, read the APPF News.

Figure: Dr Malachy Campell in The Plant Accelerator® at the Australian Plant Phenomics Facility’s Adelaide node