Relationships among Genetic, Structural, and Functional Properties of Rice Starch

Abstract

We determined the relationships among the structural properties, in vitro digestibility, and genetic factors in starches of 14 rice cultivars. Weight-based chain-length distributions in amylopectin ranged from 18.07% to 24.71% (fa, DP 6-12), 45.01% to 55.67% (fb1, DP 13-24), 12.72% to 14.05% (fb2, DP 25-36), and 10.80 to 20.72% (fb3, DP > 36), respectively. The contents of rapidly digestible starch (RDS), slowly digestible starch (SDS), and resistant starch (RS) ranged from 78.5% to 87.5%, 1.2% to 6.0%, and 10.1% to 18.0%, respectively. AAC was negatively correlated with RDS content but positively correlated with RS content in rice starch. The proportion of short chains in amylopectin, i.e. the amount of fraction IIa (FrIIa) fractionated by gel permeation chromatography (GPC), was positively correlated with RDS. Starch synthase IIa (SSIIa) gene controlled the degree of crystallinity, the amount of fa chains of amylopectin. SSIIIa gene controlled the amount of fb1 chains. Wx gene controlled the FrI, FrIIa, RDS, and RS. Starch debranching enzyme isoamylase II (ISA2) gene also controlled the RDS, which may suggest that RDS was also affected by amylopectin structure, although no correlation between them was found. This study indicated that genetics (i.e., starch biosynthesis related genes) controlled the structural properties of starch, and both amylose content and amylopectin fine structure determined functional properties of rice starch (i.e., the digestion), each in a different way. Understanding the "genetics-structure-function" relationships in rice starches will assist plant breeders and food processors in developing new rice varieties and functional foods.

Association Analysis of Markers Derived from Starch Biosynthesis Related Genes with Starch Physicochemical Properties in the USDA Rice Mini-Core Collection

“…This pattern of genetic divergence could provide an explanation for the conflicting findings about rice starch physicochemical properties in some previous studies. For example, some studies reported that AAC was positively correlated with PV whereas others found that the two parameters were negatively correlated or had not a strong relationship (Caffagni et al, 2013; Yang et al, 2014; Kong et al, 2015). This kind of discrepancy is probably due to different sample constitutions in different studies.…”

“…Amylose is linear with few branches while amylopectin is highly branched. Amylose content and the fine structure of amylopectin are the main determinants of rice eating and cooking quality (Juliano, 1985; Bao et al, 2009; Syahariza et al, 2013; Kong et al, 2015). Apparent amylose content (AAC), gelatinization temperature (GT) and gel consistency had been established and still routinely used for grain quality evaluation (Juliano, 1985).…”

Physicochemical and structural characteristics of starches from Chinese hull‐less barley cultivars

“…The debranching reaction was conducted at room temperature with constant stirring overnight and terminated by heating. The sample was centrifuged and filtrated (pore size 0.45 μm) before injection into the HPLC system (Kong et al ., 2015a).…”

Characterization of the chemical and structural properties of native and acetylated starches from avocado (Persea americana Mill.) seeds

“…Madruga et al [19] reported round or bell shapes and sizes ranging from 6 to 13 µm for native starch granules of the soft jackfruit seed (Artocarpus heterophyllus L), while Li et al [33] observed granules of round, triangle, and elliptical forms with sizes ranging from 3.3 to 126.2 µm for the native starch granules of acorn seeds (Quercus glandulifera BL). Additionally, it is known that the functional properties of native and modified starches are related to the molecular structures and arrangements of amylose and amylopectin in the granules rather than to granule shape and size [34] . The X-ray diffractogram for native starch, shown in Fig.…”