Rice Soluble Starch Synthase I: Allelic Variation, Expression, Function, and Interaction With Waxy.

Area of Science:

• Plant Biology
• Agricultural Science
• Genetics

Background:

• Starch composition (amylose and amylopectin) is crucial for rice quality.
• Soluble starch synthase I (SSSI) is a key enzyme in amylopectin synthesis, accounting for most soluble starch synthase activity.

Purpose of the Study:

• Investigate SSSI allelic variation, its impact on rice physicochemical properties and quality.
• Explore interactions between SSSI and the Waxy (Wx) gene in rice.

Main Methods:

• Analyzed SSSI nucleotide polymorphisms in 165 rice varieties.
• Utilized promoter-Beta-Glucuronidase (β-GUS) assays and RNA interference (RNAi) to study gene expression and function.
• Generated near-isogenic lines (NILs) to assess SSSI effects and Wx gene interactions.

Main Results:

• SSSI promoter polymorphisms correlate with differential expression between indica and japonica subspecies.
• SSSI variation affects thermal properties, gel consistency, and granule structure.
• SSSI knockdown impacts apparent amylose content and taste value, with effects modulated by Wx alleles.

Conclusions:

• SSSI allelic variation significantly influences rice physicochemical properties and eating quality.
• SSSI's effect on rice quality is context-dependent, involving interactions with the Wx gene.
• Findings provide insights for breeding rice with improved eating and cooking qualities.