AUTHOR=Liang Cheng , Xu Haoyang , You Hui , Zhang Ouling , Han Yiman , Li Qingyu , Hu Yungao , Xiang Xunchao 

TITLE=Physicochemical properties and molecular mechanisms of different resistant starch subtypes in rice

JOURNAL=Frontiers in Plant Science

VOLUME=14

YEAR=2024

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2023.1313640

DOI=10.3389/fpls.2023.1313640

ISSN=1664-462X

ABSTRACT=<p>Resistant starch (RS) can help prevent diabetes and decrease calorie intake and that from plants are the main source of mankind consumption. Rice is many people’s staple food and that with higher RS will help health management.  A significantly positive correlation exists between apparent amylose content (AAC) of rice and its RS content. In this study, 72 accessions with moderate or high AAC were selected to explore the regulatory mechanisms and physicochemical properties on different proceeding types of rice RS. RS in raw milled rice (RSm), hot cooked rice (RSc), and retrogradation rice (RSr) showed a wide variation and distinct controlling mechanisms. They were co-regulated by <italic>Waxy</italic> (<italic>Wx</italic>), <italic>soluble starch synthase</italic> (<italic>SS</italic>) <italic>IIb</italic> and <italic>SSI</italic>. Besides that, RSm was also regulated by <italic>SSIIa</italic> and <italic>SSIVb</italic>, RSc by <italic>granule-bound starch synthase</italic> (<italic>GBSS</italic>) <italic>II</italic> and RSr by <italic>GBSSII</italic> and <italic>Pullulanase</italic> (<italic>PUL</italic>). Moreover, <italic>Wx</italic> had significant interactions with <italic>SSIIa</italic>, <italic>SSI</italic>, <italic>SSIIb</italic> and <italic>SSIVb</italic> on RSm, but only the dominant interactions with <italic>SSIIb</italic> and <italic>SSI</italic> on RSc and RSr. <italic>Wx</italic> was the key factor for the formation of RS, especially the RSc and RSr. The genes had the highest expression at 17 days after flowering and were beneficial for RS formation. The longer the chain length of starch, the higher the RS3 content. RSc and RSr were likely to be contained in medium-size starch granules. The findings favor understanding the biosynthesis of different subtypes of RS.</p>