Huang Juan, Liu Fei, Zhang Jieqiong, Tang Bin, Deng Jiao, Shi Taoxiong, Zhu Liwei, Li Hongyou, Chen Qingfu
Research Center of Buckwheat Industry Technology, College of Life Science, Guizhou Normal University, Guiyang 550025, China.
Guizhou Provincial Agricultural Technology Extension Station, Guiyang 550001, China.
Plants (Basel). 2025 Jan 13;14(2):203. doi: 10.3390/plants14020203.
Tartary buckwheat is a nutrient-rich pseudo-cereal whose starch contents, including amylose and amylopectin contents, and their properties hold significant importance for enhancing yield and quality. The granule-bound starch synthase (GBSS) is a key enzyme responsible for the synthesis of amylose, directly determining the amylose content and amylose-to-amylopectin ratio in crops. Although one has already been cloned, the genes at the genome-wide level have not yet been fully assessed and thoroughly analyzed in Tartary buckwheat. This study comprehensively analyzed the in Tartary buckwheat. Based on the genome data of Tartary buckwheat, five genes, namely to , were identified on three chromosomes, exhibiting about 1800 bp lengths in their CDSs and numerous exons and introns in gene structures. Amino acid analyses revealed high homology in ten GBSS proteins from Tartary buckwheat, rice, maize, and , with a specific starch synthase catalytic domain and ten conserved motifs. The Tartary buckwheat GBSS proteins had a closer relationship with GBSS proteins from monocot based on evolutionary relationship analysis. Expression analyses suggested that the genes showed distinct tissue-specific expression patterns in Tartary buckwheat and rice-Tartary buckwheat. Among them, , , and were higher expressed in the root, stem, or flower, suggesting that they have a role in the amylose synthesis of these tissues. Notably, and were more highly expressed in seeds than in other tissues, suggesting that they have a pivotal role in amylose synthesis of the seeds of Tartary buckwheat. Furthermore, the cis acting elements in the promoters of and their binding transcription factors (TFs) were investigated. A protein-protein interaction network was constructed and co-expression was analyzed based on the gene expression patterns of the , and the identified TFs, belonging to bZIP, ERF, bHLH, and MADS-box TF families, were identified within this network, and their expression patterns were significantly correlated to the expression patterns of two seed-specific genes ( and ). Finally, was successfully transformed into rice through transgenic manipulation, and the overexpression lines showed an increase in amylose content accompanied by a reduction in amylopectin and total starch contents compared with WT. Overall, this research not only deepens our understanding of the molecular mechanisms of amylose synthesis in Tartary buckwheat, but also provides scientific insights for enhancing crop amylose content and quality through molecular breeding.
苦荞是一种营养丰富的假谷物，其淀粉含量（包括直链淀粉和支链淀粉含量）及其特性对于提高产量和品质具有重要意义。颗粒结合型淀粉合酶（GBSS）是负责直链淀粉合成的关键酶，直接决定作物中的直链淀粉含量和直链淀粉与支链淀粉的比例。尽管已经克隆了一个GBSS基因，但苦荞全基因组水平的GBSS基因尚未得到充分评估和深入分析。本研究对苦荞中的GBSS基因进行了全面分析。基于苦荞的基因组数据，在三条染色体上鉴定出五个GBSS基因，即FtGBSS1到FtGBSS5，其编码序列（CDS）长度约为1800 bp，基因结构中有多个外显子和内含子。氨基酸分析显示，苦荞、水稻、玉米和拟南芥的十种GBSS蛋白具有高度同源性，具有特定的淀粉合酶催化结构域和十个保守基序。基于进化关系分析，苦荞GBSS蛋白与单子叶植物的GBSS蛋白关系更为密切。表达分析表明，GBSS基因在苦荞和水稻-苦荞杂种中表现出明显的组织特异性表达模式。其中，FtGBSS1、FtGBSS2和FtGBSS3在根、茎或花中高表达，表明它们在这些组织的直链淀粉合成中发挥作用。值得注意的是，FtGBSS4和FtGBSS5在种子中的表达高于其他组织，表明它们在苦荞种子的直链淀粉合成中起关键作用。此外，还研究了FtGBSS4和FtGBSS5启动子中的顺式作用元件及其结合转录因子（TFs）。构建了蛋白质-蛋白质相互作用网络，并根据FtGBSS4和FtGBSS5以及已鉴定的TFs的基因表达模式进行了共表达分析，在该网络中鉴定出属于bZIP、ERF、bHLH和MADS-box TF家族的TFs，它们的表达模式与两个种子特异性GBSS基因（FtGBSS4和FtGBSS5）的表达模式显著相关。最后，通过转基因操作将FtGBSS4成功转入水稻，与野生型相比，FtGBSS4过表达株系的直链淀粉含量增加，支链淀粉和总淀粉含量降低。总体而言，本研究不仅加深了我们对苦荞直链淀粉合成分子机制的理解，也为通过分子育种提高作物直链淀粉含量和品质提供了科学依据。
