ICAR-National Institute for Plant Biotechnology, New Delhi, India.
ICAR-Central Arid Zone Research Institute, Jodhpur, India.
Sci Rep. 2021 Feb 17;11(1):4000. doi: 10.1038/s41598-021-83507-3.
Galactomannan is a polymer of high economic importance and is extracted from the seed endosperm of clusterbean (C. tetragonoloba). In the present study, we worked to reveal the stage-specific galactomannan biosynthesis and its regulation in clusterbean. Combined electron microscopy and biochemical analysis revealed high protein and gum content in RGC-936, while high oil bodies and low gum content in M-83. A comparative transcriptome study was performed between RGC-936 (high gum) and M-83 (low gum) varieties at three developmental stages viz. 25, 39, and 50 days after flowering (DAF). Total 209,525, 375,595 and 255,401 unigenes were found at 25, 39 and 50 DAF respectively. Differentially expressed genes (DEGs) analysis indicated a total of 5147 shared unigenes between the two genotypes. Overall expression levels of transcripts at 39DAF were higher than 50DAF and 25DAF. Besides, 691 (RGC-936) and 188 (M-83) candidate unigenes that encode for enzymes involved in the biosynthesis of galactomannan were identified and analyzed, and 15 key enzyme genes were experimentally validated by quantitative Real-Time PCR. Transcription factor (TF) WRKY was observed to be co-expressed with key genes of galactomannan biosynthesis at 39DAF. We conclude that WRKY might be a potential biotechnological target (subject to functional validation) for developing high gum content varieties.
半乳甘露聚糖是一种具有重要经济价值的聚合物，从兵豆（C. tetragonoloba）的种胚乳中提取。在本研究中，我们致力于揭示兵豆中半乳甘露聚糖生物合成的阶段性及其调控机制。结合电子显微镜和生化分析，发现 RGC-936 中蛋白质和胶含量高，而 M-83 中油体含量高且胶含量低。在三个发育阶段（开花后 25、39 和 50 天）对 RGC-936（高胶）和 M-83（低胶）品种进行了比较转录组研究。在 25、39 和 50 DAF 分别发现了 209525、375595 和 255401 个全长基因。在两个基因型之间，差异表达基因（DEGs）分析表明共有 5147 个共享基因。39 DAF 的转录本总体表达水平高于 50 DAF 和 25 DAF。此外，鉴定并分析了 691 个（RGC-936）和 188 个（M-83）候选基因，这些基因编码参与半乳甘露聚糖生物合成的酶，通过定量实时 PCR 实验验证了 15 个关键酶基因。在 39 DAF 时观察到 WRKY 转录因子与半乳甘露聚糖生物合成的关键基因共表达。我们得出结论，WRKY 可能是开发高胶含量品种的潜在生物技术靶点（有待功能验证）。
