籼稻背景下导入Wx~(in)等位基因改良稻米食味和理化品质

水稻Wx~b等位基因已广泛用于籼稻的品质改良,但携带该等位基因的一些籼稻米饭往往偏软,仍需进一步改良。为明确籼稻背景下导入Wxin等位基因对稻米食味品质和理化品质的效应,分别以携带Wxin的IR64和携带Wx~b的9311为供体,以携带Wxa的籼稻SIR3611 (3611)为受体,基于分子标记辅助选择,通过杂交和连续回交的方式构建了3611背景下携带Wxin和Wx~b的近等基因系。系统比较了不同近等基因系间的农艺性状以及稻米的食味和理化品质。结果表明,近等基因系与受体亲本3611的主要农艺性状基本接近,无显著差异。NIL(Wxin)稻米的表观直链淀粉含量较亲本3611极显著下降而胶稠度极显著增加。NIL(Wx~b)稻米表观直链淀粉含量最低且与之对应的胶稠度最高。近等基因系NIL(Wxin)和NIL(Wx~b)稻米的食味值较亲本极显著提高。NIL(Wx~(in))和NIL(Wx~b)稻米的GBSSI丰度与对应的表观直链淀粉含量具有明显的正相关。稻米粉的黏滞性谱、热糊化特性和晶体结构与直链淀粉含量显著相关性。本研究为在我国籼稻品种品质改良中有效利用Wxin等位基因提供了重要依据。

Improvement of rice eating quality and physicochemical properties by introgression of Wx in allele in indica varieties

Nowadays, the Wx ^b allele has been widely used to improve grain quality of indica rice. However, some indica varieties carrying Wx ^b allele usually has a much softer texture, which is not favored by consumers in South China. So the grain quality of these varieties needs to be further improved. To understand the effect of Wx ⁱⁿ allele on rice eating quality and physicochemical properties in indica rice, we developed two Near-Isogenic Lines (NILs) carrying Wx ⁱⁿ and Wx ^b alleles by crossing an indica variety 3611 (receptor, carrying Wx ^a) with IR64 (carrying Wx ⁱⁿ) and 9311 (carrying Wx ^b), and seven times of backcrossing based on molecular marker assistant selection (MAS). The Wx effects in controlling the synthesis of amylose, grain quality, and physicochemical properties were investigated. There were non-significant differences in the agronomic traits among the NILs. However, for grain quality characters, we found that the NIL(Wx ⁱⁿ) rice showed significantly lower apparent amylose content (AAC) and higher gel consistency (GC), compared with the wild type 3611. Besides, the NIL(Wx ^b) rice showed the lowest AAC and highest GC among three lines. The NIL(Wx ⁱⁿ) rice had a significantly higher taste value than the wild type 3611, while the NIL(Wx ^b) rice exhibited the highest taste value among the three samples. The granule-bound starch synthase I (GBSSI) level was the highest in 3611, moderate in NIL(Wx ⁱⁿ) and lowest in NIL(Wx ^b), which showed a positive correlation with the AAC level. Also, the starch viscosity, thermal gelatinization property and crystal structure of different rice flours had a high correlation with the AAC level. To sum up, our results proved that both Wx ⁱⁿ and Wx ^b allele can improve the grain quality in 3611 background, and what is more, the Wx ⁱⁿ allele might be more useful for the improvement of grain quality in indica rice.