Postgraduate Institute of Agriculture, University of Peradeniya, Peradeniya, Sri Lanka.
Food Research Unit, Department of Agriculture, Peradeniya, Sri Lanka.
BMC Plant Biol. 2024 Sep 28;24(1):884. doi: 10.1186/s12870-024-05623-2.
Antioxidant properties of rice provide various health benefits due to its ability to inhibit cellular oxidation. Antioxidant content of rice is known to be linked with the pericarp pigmentation. The Rc gene of rice (Os07g0211500) codes for a basic helix-loop-helix (bHLH) protein, acting as a transcriptional factor in regulating proanthocyanidin biosynthesis. The current study was carried out to evaluate the variation of antioxidant properties in a selected panel of rice accessions and assess the possibility of using haplotypes defined based on the Rc gene to predict pericarp pigmentation and antioxidant content in rice.
Thirty-two rice accessions were evaluated for grain pericarp colour and antioxidant properties; total phenolic content (TPC), total flavonoids (TFC), proanthocyanidins (PAC) and radical scavenging activity (RSA). The parameters TPC, TFC and PAC showed significant positive correlation with RSA (r > 0.69; P < 0.01). The study panel showed a wide variation for antioxidant properties and rice accessions such as Sudu Heenati, Deweraddiri, Madathawalu, Masuran, Ld 368, At 311, Kalu Heenati, Bw 272-6B, Pokkali, At 362 and Wanni Dahanala exhibited profound potential with respect to antioxidant properties. Based on three-target sites previously reported as critical for the function of the coded bHLH protein (an A/C SNP at 1,353-bp, a 1-bp insertion/deletion at 1,388-bp, and a 14-bp insertion/deletion at 1,408-1,421-bp positioned in the mRNA corresponding to the exon 6 of rice Rc gene), three haplotypes were defined (H1-H3). Pigmentation of the rice pericarp could be successfully explained based on the defined haplotypes (H1 (C/G/+): red, and H2 (A/G/+) and H3 (C/G/-): white), and the H1 haplotype corresponded to a significantly (P < 0.05) higher TPC, TFC, PAC and RSA compared to the other haplotypes.
The studied rice accessions showed a significant variation with respect to antioxidant properties. Haplotype H1 defined based on the three-target sites in the exon 6 of Rc gene can detect rice accessions with red pigmented pericarp and high antioxidant properties effectively. Hence, its use can be recommended as an alternative to biochemical assays for screening during rice breeding programs.
由于其抑制细胞氧化的能力，大米的抗氧化特性为其提供了各种健康益处。已知大米的抗氧化含量与种皮色素沉着有关。水稻的 Rc 基因（Os07g0211500）编码一个碱性螺旋-环-螺旋（bHLH）蛋白，作为调节原花青素生物合成的转录因子。本研究旨在评估选定的水稻品系的抗氧化特性变化，并评估基于 Rc 基因定义的单倍型是否有可能预测水稻的种皮色素沉着和抗氧化含量。
对 32 个水稻品系的籽粒种皮颜色和抗氧化特性进行了评价；总酚含量（TPC）、总类黄酮（TFC）、原花青素（PAC）和自由基清除活性（RSA）。参数 TPC、TFC 和 PAC 与 RSA 呈显著正相关（r > 0.69；P < 0.01）。研究小组在抗氧化特性方面表现出广泛的变化，Sudu Heenati、Deweraddiri、Madathawalu、Masuran、Ld 368、At 311、Kalu Heenati、Bw 272-6B、Pokkali、At 362 和 Wanni Dahanala 等水稻品系表现出了显著的抗氧化特性。基于先前报道的三个关键功能位点（位于编码 bHLH 蛋白的外显子 6 的 1,353-bp 处的 A/C SNP、1,388-bp 处的 1-bp 插入/缺失以及 1,408-1,421-bp 处的 14-bp 插入/缺失），定义了三个单倍型（H1-H3）。根据定义的单倍型（H1（C/G/+）：红色，和 H2（A/G/+）和 H3（C/G/-）：白色）可以成功解释水稻种皮的色素沉着，并且 H1 单倍型与 TPC、TFC、PAC 和 RSA 显著相关（P < 0.05）与其他单倍型相比，更高。
研究的水稻品系在抗氧化特性方面表现出显著差异。基于 Rc 基因外显子 6 中的三个目标位点定义的单倍型 H1 可以有效地检测具有红色种皮和高抗氧化特性的水稻品系。因此，建议在水稻育种计划中作为生化分析的替代方法进行筛选。
