FLOURY ENDOSPERM 2 Coordinates Starch Biosynthesis to Maintain Endosperm Structural Integrity in Rice

Area of Science:

• Plant Biology
• Molecular Genetics
• Food Science

Background:

• FLOURY ENDOSPERM 2 (FLO2) is implicated in rice endosperm development and starch quality.
• The precise quantitative impact of FLO2 on flour physicochemical behavior and endosperm integrity remains undefined.

Purpose of the Study:

• To investigate the role of FLO2 in rice by analyzing the effects of its loss of function on starch organization.
• To quantitatively define how mutations in FLO2 alter the functional properties of rice flour and endosperm microstructure.

Main Methods:

• Generated homozygous OsFLO2 knockout lines using CRISPR/Cas9 in japonica rice.
• Assessed grain appearance, flour physicochemical properties (RVA, DSC), amylopectin chain-length distribution, and endosperm microstructure (SEM).

Main Results:

• OsFLO2 mutants displayed floury, opaque endosperms with increased chalkiness (27-29%).
• Significant reductions in peak viscosity and pasting temperature were observed, alongside altered amylopectin chain lengths and increased endosperm porosity.
• Disrupted starch granule packing and a tendency toward reduced gelatinization enthalpy were noted in mutants.

Conclusions:

• FLO2 is essential for maintaining rice endosperm structural integrity.
• The gene plays a critical role in harmonizing amylopectin microstructure with starch thermal and gelatinization properties.
• Understanding FLO2 function provides insights into improving rice flour quality and endosperm characteristics.