Disruption of the Karrikin Receptor DWARF 14 LIKE (D14L) Gene Leads to Distinct Effects on Root and Shoot Growth, and Reprogramming of Central Metabolism in Rice.

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The rice (Oryza sativa L.) α/β hydrolase D14 LIKE (D14L), a paralog of the strigolactone receptor D14, is essential for the establishment of arbuscular mycorrhizal (AM) symbiosis and responses to karrikins, smoke-derived compounds that regulate several developmental processes. It is supposed that D14L is the receptor for a yet unidentified endogenous growth regulator. Herein, we determined the effects of disrupting the D14L on rice growth and metabolism. Our results revealed that the D14L loss of function altered rice architecture, leading to a significant increase in root growth and mesocotyl elongation, while hindering shoot growth, and a notable decrease in the number of tillers, especially under phosphate limiting conditions. Furthermore, d14l mutants exhibited significant reduction in the total grain yield. Metabolomics analysis revealed a notable shift of key metabolites, such as carbohydrates and amino acids involved in energy production and growth, from shoots to roots. This redistribution likely reflects an adaptive strategy to enhance nutrient acquisition and increase root biomass, albeit at the cost of shoot growth and productivity. Our findings highlight the pivotal role of D14L in regulating the root-to-shoot growth ratio and in coordinating the metabolism and allocation of resources across the rice plant.