Background

Rice amylose content and amylopectin structure corporately determine rice eating and cooking qualities (ECQs). Soluble starch synthase (SS) IV-2 is a member of the soluble starch synthesis gene family but with unknown effects on ECQs.

Results

In this study, three populations derived from a cross of two parents who possess the same major genes of starch bio-synthesis were employed to investigate the influence of SSIV-2 and its combined effects with ADPglucose pyrophorylase large unit (AGPlar) and Pullulanase (PUL) on ECQs. The results illustrated that the polymorphism of SSIV-2 alleles significantly affected gel consistency (GC), gelatinization temperature (GT), percent of retrogradation (PR) and three crucial rapid viscosity analysis (RVA) profile parameters: peak viscosity (PKV), breakdown viscosity (BDV) and setback viscosity (SBV). And SSIV-2 allele derived from CG173R had better quality traits with lower GT, SBV and PR. Moreover, its interaction with AGPlar was responsible for the variations of GC, apparent amylose content (AAC), GT, PR and all RVA parameters except for pasting temperature (PaT) and peak time (PeT), in terms of GC, PKV and CSV, AGPlar derived from CG173R had an epistatic effect on SSIV-2; additionally, interaction of SSIV-2 and PUL mainly affected GC, AAC, PKV, CPV, CSV and SBV. I-C and C-1 (I, allele of AGPlar from Guangzhan 63S; C, allele of SSIV-2 from CG173R; 1, allele of PUL from Guangzhan 63S) combinations had better ECQs.

Conclusions

SSIV-2 alleles significantly affect rice quality, especially the parameters relevant to gelatinized and thermal characteristics of starch (GC, PR, GT, PKV, BDV and SBV) under the same major genes (Waxy and SSII-3) background. It indicates that SSIV-2 functions elongation of starch chain. These findings suggest that the effects of SSIV-2 and its interaction with AGPlar and PUL are vital for rice quality breeding with the same major genes.

中文翻译：

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可溶性淀粉合酶IV-2及其与ADP葡萄糖焦磷酸化酶大单位和支链淀粉酶对水稻品质的遗传效应。

背景

大米的直链淀粉含量和支链淀粉的结构共同决定了大米的食用和烹饪质量（ECQ）。可溶性淀粉合成酶（SS）IV-2是可溶性淀粉合成基因家族的成员，但对ECQ的影响未知。

结果

在这项研究中，使用了具有相同淀粉生物合成主要基因的两个亲本的杂交衍生的三个种群，以研究SSIV-2的影响及其与ADP葡萄糖焦脱氧酶大单位（AGPlar）和支链淀粉酶（PUL）的联合作用）上的ECQ。结果表明，SSIV-2等位基因的多态性显着影响凝胶稠度（GC），糊化温度（GT），回生率（PR）和三个关键的快速粘度分析（RVA）曲线参数：峰粘度（PKV），分解粘度（BDV）和缩进粘度（SBV）。和SSIV-2源自CG173R的等位基因具有较好的品质性状，而GT，SBV和PR较低。此外，它与AGPlar的相互作用导致GC，表观直链淀粉含量（AAC），GT，PR和所有RVA参数（除了糊化温度（PaT）和峰值时间（PeT））以外的变化（以GC，PKV和CSV表示） ，AGPlar从CG173R衍生对一个上位性效应SSIV-2 ; 另外，SSIV-2和PUL的相互作用主要影响GC，AAC，PKV，CPV，CSV和SBV。IC和C-1组合（I，来自广站63S的AGPlar的等位基因； C，来自CG173R的SSIV-2的等位基因； 1，来自广站63S的PUL的等位基因）组合具有更好的ECQ。

结论

在相同的主要基因（Waxy和SSII-3）背景下，SSIV-2等位基因显着影响水稻品质，特别是与淀粉（GC，PR，GT，PKV，BDV和SBV）的糊化和热特性相关的参数。这表明SSIV-2具有延长淀粉链的功能。这些发现表明，SSIV-2的作用及其与AGPlar和PUL的相互作用对于具有相同主要基因的水稻品质育种至关重要。