Rice ORMDL controls sphingolipid homeostasis affecting fertility resulting from abnormal pollen development.

Area of Science:

• Plant molecular biology
• Genetics
• Biochemistry

Background:

• Orosomucoid (ORM) and ORMDL (ORM-like) genes encode ER-resident polypeptides.
• In humans, ORMDL3 is linked to asthma risk; in yeast, ORMs regulate sphingolipid synthesis.
• The function of ORM/ORMDL genes in plants remains largely uncharacterized.

Purpose of the Study:

• Investigate the role of rice ORMDL genes in plant fertility.
• Identify candidate genes responsible for temperature-sensitive genetic male sterility (TGMS) in rice.
• Elucidate the function of rice ORMDL genes in sphingolipid homeostasis and pollen development.

Main Methods:

• Quantified expression of candidate ORMDL genes in wild-type rice anthers under fertile and sterile conditions.
• Generated RNAi transgenic rice plants to suppress specific ORMDL genes (LOC_Os07g26940) or all three ORMDL genes.
• Analyzed sphingolipid metabolism and gene expression in tms2 mutant rice.

Main Results:

• The rice ORMDL gene (LOC_Os07g26940) exhibited differential expression in anthers correlating with fertility.
• RNAi-suppressed rice plants showed sterility with abnormal pollen morphology and staining.
• Sphingolipid metabolism and synthesis gene expression were perturbed in the tms2 mutant.

Conclusions:

• Plant ORMDL proteins are essential for maintaining sphingolipid homeostasis.
• Disruption of ORMDL gene function leads to male sterility due to impaired pollen development.
• Rice ORMDL genes play a critical role in plant reproductive success.