Rice Non-Specific Phospholipase C6 Is Involved in Mesocotyl Elongation

Area of Science:

• Plant Biology
• Molecular Biology
• Biochemistry

Background:

• Mesocotyl elongation is vital for rice seedling emergence from deep soil.
• Phospholipid signaling mechanisms in rice mesocotyl growth remain largely unknown.
• Non-specific phospholipase C (NPC) enzymes play roles in cellular signaling pathways.

Purpose of the Study:

• To investigate the role of rice non-specific phospholipase C6 (OsNPC6) in rice mesocotyl elongation.
• To elucidate the involvement of phospholipid signaling, specifically phosphocholine (PCho), in this process.
• To understand the interaction between OsNPC6, PCho, and gibberellic acid (GA) signaling.

Main Methods:

• Analysis of OsNPCs' substrate hydrolysis and subcellular localization.
• Phenotypic characterization of OsNPC6 overexpression (OE) and mutant (npc6) rice lines.
• Gibberellic acid (GA3) treatment and measurement of SLENDER RICE1 (SLR1) protein levels.
• Assessment of PCho supplementation effects on mesocotyl elongation and gene expression.

Main Results:

• All five rice OsNPCs hydrolyze phosphatidylcholine to phosphocholine (PCho) and localize to the plasma membrane.
• OsNPC6 overexpression resulted in shorter mesocotyls, while npc6 mutants showed GA3-enhanced elongation.
• GA3 treatment increased SLR1 levels in OE plants but decreased them in npc6 mutants; PCho supplementation reversed these effects.
• PCho supplementation attenuated GA-induced mesocotyl elongation and weakened GA-induced expression of phospho-base N-methyltransferase 1 in npc6 mutants.

Conclusions:

• OsNPC6 plays a significant role in rice mesocotyl development.
• OsNPC6 modulates mesocotyl elongation through the regulation of phosphocholine (PCho) levels.
• The OsNPC6-PCho pathway interacts with gibberellic acid (GA) signaling, specifically affecting SLR1 stability and downstream gene expression.