Abstract：
BACKGROUND: Colored barley, which may have associated human health benefits, is more desirable than the standard white variety, but the metabolites and molecular mechanisms underlying seedcoat coloration remain unclear.
RESULTS: Here, the development of Tibetan hulless barley was monitored, and 18 biological samples at 3 seedcoat color developmental stages were analyzed by transcriptomic and metabolic assays in Nierumuzha (purple) and Kunlun10 (white). A total of 41 anthocyanin compounds and 4186 DEGs were identified. Then we constructed the proanthocyanin-anthocyanin biosynthesis pathway of Tibetan hulless barley, including 19 genes encoding structural enzymes in 12 classes (PAL, C4H, 4CL, CHS, CHI, F3H, F3\'H, DFR, ANS, ANR, GT, and ACT). 11 DEGs other than ANR were significantly upregulated in Nierumuzha as compared to Kunlun10, leading to high levels of 15 anthocyanin compounds in this variety (more than 25 times greater than the contents in Kunlun10). ANR was significantly upregulated in Kunlun10 as compared to Nierumuzha, resulting in higher contents of three anthocyanins compounds (more than 5 times greater than the contents in Nierumuzha). In addition, 22 TFs, including MYBs, bHLHs, NACs, bZips, and WD40s, were significantly positively or negatively correlated with the expression patterns of the structural genes. Moreover, comparisons of homologous gene sequences between the two varieties identified 61 putative SNPs in 13 of 19 structural genes. A nonsense mutation was identified in the coding sequence of the ANS gene in Kunlun10. This mutation might encode a nonfunctional protein, further reducing anthocyanin accumulation in Kunlun10. Then we identified 3 modules were highly specific to the Nierumuzha (purple) using WGCNA. Moreover, 12 DEGs appeared both in the putative proanthocyanin-anthocyanin biosynthesis pathway and the protein co-expression network were obtained and verified.
CONCLUSIONS: Our study constructed the proanthocyanin-anthocyanin biosynthesis pathway of Tibetan hulless barley. A series of compounds, structural genes and TFs responsible for the differences between purple and white hulless barley were obtained in this pathway. Our study improves the understanding of the molecular mechanisms of anthocyanin accumulation and biosynthesis in barley seeds. It provides new targets for the genetic improvement of anthocyanin content and a framework for improving the nutritional quality of barley.
RESULTS: Here, the development of Tibetan hulless barley was monitored, and 18 biological samples at 3 seedcoat color developmental stages were analyzed by transcriptomic and metabolic assays in Nierumuzha (purple) and Kunlun10 (white). A total of 41 anthocyanin compounds and 4186 DEGs were identified. Then we constructed the proanthocyanin-anthocyanin biosynthesis pathway of Tibetan hulless barley, including 19 genes encoding structural enzymes in 12 classes (PAL, C4H, 4CL, CHS, CHI, F3H, F3\'H, DFR, ANS, ANR, GT, and ACT). 11 DEGs other than ANR were significantly upregulated in Nierumuzha as compared to Kunlun10, leading to high levels of 15 anthocyanin compounds in this variety (more than 25 times greater than the contents in Kunlun10). ANR was significantly upregulated in Kunlun10 as compared to Nierumuzha, resulting in higher contents of three anthocyanins compounds (more than 5 times greater than the contents in Nierumuzha). In addition, 22 TFs, including MYBs, bHLHs, NACs, bZips, and WD40s, were significantly positively or negatively correlated with the expression patterns of the structural genes. Moreover, comparisons of homologous gene sequences between the two varieties identified 61 putative SNPs in 13 of 19 structural genes. A nonsense mutation was identified in the coding sequence of the ANS gene in Kunlun10. This mutation might encode a nonfunctional protein, further reducing anthocyanin accumulation in Kunlun10. Then we identified 3 modules were highly specific to the Nierumuzha (purple) using WGCNA. Moreover, 12 DEGs appeared both in the putative proanthocyanin-anthocyanin biosynthesis pathway and the protein co-expression network were obtained and verified.
CONCLUSIONS: Our study constructed the proanthocyanin-anthocyanin biosynthesis pathway of Tibetan hulless barley. A series of compounds, structural genes and TFs responsible for the differences between purple and white hulless barley were obtained in this pathway. Our study improves the understanding of the molecular mechanisms of anthocyanin accumulation and biosynthesis in barley seeds. It provides new targets for the genetic improvement of anthocyanin content and a framework for improving the nutritional quality of barley.
摘要：
背景：彩色大麦，可能对人类健康有益，比标准的白色品种更可取，但是种皮着色的代谢物和分子机制尚不清楚。
结果：这里，对西藏无壳大麦的发展进行了监测，通过转录组学和代谢测定，在Nierumuzha（紫色）和Kunlun10（白色）中分析了3个种皮颜色发育阶段的18个生物样品。共鉴定出41种花色苷化合物和4186种DEGs。构建了西藏无壳大麦原花青素-花青素生物合成途径,包括12类结构酶的19个基因(PAL，C4H,4CL,CHS,CHI,F3H,F3\'H,DFR,ANS,ANR,GT,和ACT）。与Kunlun10相比，Nierumuzha中除ANR以外的11个DEG显着上调，导致该品种中15种花青素苷化合物的含量很高（比Kunlun10中的含量高25倍以上）。与Nierumuzha相比，Kunlun10中的ANR显着上调，导致三种花色苷化合物的含量较高（比Nierumuzha中的含量高5倍以上）。此外,22个TFs，包括MYBs,bHLHs,NAC,bZips,和WD40，与结构基因的表达模式呈显著正相关或负相关。此外，两个品种之间同源基因序列的比较在19个结构基因中的13个中鉴定出61个推定的SNP。在Kunlun10中的ANS基因的编码序列中鉴定出无义突变。这种突变可能编码一种无功能的蛋白质，进一步减少Kunlun10的花色苷积累。然后，我们使用WGCNA鉴定了3个模块对Nierumuzha（紫色）具有高度特异性。此外，获得并验证了12个DEGs同时出现在假定的原花青素-花青素生物合成途径和蛋白质共表达网络中。
结论：我们的研究构建了西藏无壳大麦原花青素-花青素的生物合成途径。一系列的化合物,在该途径中获得了负责紫色和白色无壳大麦之间差异的结构基因和TFs。我们的研究提高了对大麦种子中花色苷积累和生物合成的分子机制的理解。为大麦花青素含量的遗传改良提供了新的靶点,为提高大麦营养品质提供了框架。
结果：这里，对西藏无壳大麦的发展进行了监测，通过转录组学和代谢测定，在Nierumuzha（紫色）和Kunlun10（白色）中分析了3个种皮颜色发育阶段的18个生物样品。共鉴定出41种花色苷化合物和4186种DEGs。构建了西藏无壳大麦原花青素-花青素生物合成途径,包括12类结构酶的19个基因(PAL，C4H,4CL,CHS,CHI,F3H,F3\'H,DFR,ANS,ANR,GT,和ACT）。与Kunlun10相比，Nierumuzha中除ANR以外的11个DEG显着上调，导致该品种中15种花青素苷化合物的含量很高（比Kunlun10中的含量高25倍以上）。与Nierumuzha相比，Kunlun10中的ANR显着上调，导致三种花色苷化合物的含量较高（比Nierumuzha中的含量高5倍以上）。此外,22个TFs，包括MYBs,bHLHs,NAC,bZips,和WD40，与结构基因的表达模式呈显著正相关或负相关。此外，两个品种之间同源基因序列的比较在19个结构基因中的13个中鉴定出61个推定的SNP。在Kunlun10中的ANS基因的编码序列中鉴定出无义突变。这种突变可能编码一种无功能的蛋白质，进一步减少Kunlun10的花色苷积累。然后，我们使用WGCNA鉴定了3个模块对Nierumuzha（紫色）具有高度特异性。此外，获得并验证了12个DEGs同时出现在假定的原花青素-花青素生物合成途径和蛋白质共表达网络中。
结论：我们的研究构建了西藏无壳大麦原花青素-花青素的生物合成途径。一系列的化合物,在该途径中获得了负责紫色和白色无壳大麦之间差异的结构基因和TFs。我们的研究提高了对大麦种子中花色苷积累和生物合成的分子机制的理解。为大麦花青素含量的遗传改良提供了新的靶点,为提高大麦营养品质提供了框架。
