Screening 192 Thai indica rice accessions revealed wide variation in underwater coleoptile elongation and weak correspondence between anaerobic germination and anaerobic seedling development, r=0.29. Higher temperature was associated with lower dissolved oxygen and reduced elongation. Multiple QTLs and three candidate genes were identified, but gene function and field yield benefits remain unproven.
Key findings
- Stage-specific responses correlated only r=0.29, so one stage should not represent total tolerance.
- Four coleoptile-length and three elongation-index QTLs were found under anaerobic germination, plus one length QTL under anaerobic seedling development.
- OsSWEET13, OsNAM, and OsARF24 are candidates, not functionally confirmed tolerance genes.
Why this matters globally
The work may refine breeding for direct seeding and flood-prone areas by incorporating developmental stage and temperature. Food-security relevance remains prospective pending replication, field establishment, and yield testing.
Thai researcher contribution
Six Chulalongkorn University researchers placed Thai indica diversity at the centre of experiments conducted with collaborators in China, Japan, and Taiwan, linking Thai germplasm to international questions about flooding, temperature, and crop adaptation.
Limitations to consider
Temperature and dissolved oxygen covaried, candidate loci require replication and functional testing, coleoptile elongation is not equivalent to field establishment or yield, and the Thai indica panel may not represent other rice groups.