Variation of resistant starch content in different processing types and their starch granules properties in rice

Ninety-nine lines from recombinant inbred lines were selected to investigate the effects of starch synthesisrelated genes on resistant starch (RS) content in different proceeding types. RS in raw milled rice (RSm), hot cooked rice (RSc), and retrogradation rice (RSr) showed a wide variation among the lines, especially RSm arrived at 10.61%. Divergent variability of RSm, RSc and RSr indicated that there were different regulation mechanisms for them. Waxy wildtype allele (Wxa) could elevate RSm, RSc and RSr, but Soluble starch synthase IIa (SSIIa) only played a vital role in regulating RSm. Wxa-indica SSIIa could increase RSm, and Wxa-japonica SSIIa (SSIIaj) could elevate RSc and RSr. The mean diameter of Wxa-SSIIaj was significantly bigger than others. The bigger starch granules, the higher RSc and RSr. Starch granules morphology with high-RSm would have a higher percentage in polyhedral and angular shape. The results provide new information for rice breeding with high-RS content.

Automated summary

The study found that there is significant variability in resistant starch content in rice among different processing types, and different genes have different regulatory mechanisms for resistant starch content in different processing types. Strains with Waxy wildtype allele and SSIIa gene play a significant role in increasing resistant starch content.