Table_10_Transcriptome Analysis Reveals Differences in Anthocyanin Accumulation in Cotton (Gossypium hirsutum L.) Induced by Red and Blue Light.csv

Many factors, including illumination, affect anthocyanin biosynthesis and accumulation in plants. light quality is the key factor affecting the process of photoinduced anthocyanin biosynthesis and accumulation. We observed that the red color of the Upland cotton accession Huiyuan with the R1 mutation turned to normal green color under light-emitting diodes (LEDs), which inspired us to investigate the effect of red and blue lights on the biosynthesis and accumulation of anthocyanins. We found that both red and blue lights elevated accumulation of anthocyanins. Comparative transcriptomic analyses, including Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) and GSEA, revealed that genes differentially expressed under different light conditions were enriched with the pathways of circadian rhythm, phenylpropanoid biosynthesis, anthocyanin biosynthesis, and flavone and flavonol biosynthesis. Not surprisingly, all the major structural genes related to biosynthesis of anthocyanins, including the key regulatory MYB transcription factor (GhPAP1D) and anthocyanin transporter (GhGSTF12), were induced by red or blue light treatment. However, LARs and MATEs related to biosynthesis of proanthocyanidins were more significantly up-regulated by red light radiation than by blue light radiation. Vice versa, the accumulation of anthocyanins under red light was not as high as that under blue light. In addition, we demonstrated a potential role of GhHY5, a key regulator in plant circadian rhythms, in regulation of anthocyanin accumulation, which could be achieved via interaction with GhPAP1D. Together, these results indicate different effect of red and blue lights on biosynthesis and accumulation of anthocyanins and a potential module including GhHY5 and GhPAP1D in regulation of anthocyanin accumulation in cotton. These results also suggest that the substrates responsible the synthesis of anthocyanins under blue light is diverted to biosynthesis of proanthocyanidin under red light.

诸多环境因子（包括光照条件）均可影响植物体内花青素的生物合成与积累。其中光质是调控光诱导型花青素生物合成与积累过程的关键因子。本研究观察到，携带R1突变的陆地棉种质系“汇源”在发光二极管（light-emitting diodes, LEDs）照射下，原本的红色表型转变为正常绿色，这一现象启发我们开展红光与蓝光对花青素生物合成及积累影响的相关研究。研究发现，红光与蓝光均可促进花青素的积累。包括基因本体论（Gene Ontology, GO）、京都基因与基因组百科全书（Kyoto Encyclopedia of Genes and Genomes, KEGG）以及基因集富集分析（Gene Set Enrichment Analysis, GSEA）在内的比较转录组分析结果显示，不同光照条件下的差异表达基因显著富集于昼夜节律、苯丙烷生物合成、花青素生物合成以及黄酮与黄酮醇生物合成通路。不出所料，所有与花青素生物合成相关的核心结构基因，包括关键调控型MYB转录因子（GhPAP1D）以及花青素转运蛋白（GhGSTF12），均在红光或蓝光处理下被诱导表达。然而，与原花青素生物合成相关的无色花青素还原酶（leucoanthocyanidin reductase, LAR）家族基因和多药和毒性化合物外排转运蛋白（multidrug and toxic compound extrusion, MATE）家族基因，在红光照射下的上调幅度显著高于蓝光照射。反之，红光处理下的花青素积累量并未高于蓝光处理。此外，本研究证实了植物昼夜节律核心调控因子GhHY5在花青素积累调控中的潜在功能，其调控作用可通过与GhPAP1D的互作实现。综上，本研究结果揭示了红光与蓝光对花青素生物合成与积累的差异化调控效应，并提出了棉花中由GhHY5与GhPAP1D组成的潜在调控模块参与花青素积累的调控机制。本研究结果同时表明，蓝光条件下用于花青素合成的底物，在红光条件下会被分流至原花青素的生物合成途径。