China Tobacco Gene Research Center, Zhengzhou Tobacco Research Institute of CNTC, Zhengzhou, 450001, China.
Henan Agricultural University, Zhengzhou, 450002, China.
Funct Integr Genomics. 2022 Aug;22(4):537-552. doi: 10.1007/s10142-022-00851-x. Epub 2022 Apr 11.
Starch is an important primary metabolite in plants, which can provide bioenergy for fuel ethanol production. There are many studies focusing on starch metabolism in Arabidopsis, maize, and rice, but few reports have been made on the starch content of tobacco leaves. Hence, to identify the marker-trait associations and isolate the candidate genes related to starch content of tobacco leaf, the genome-wide association study (GWAS) was performed using a multiparent advanced generation intercross (MAGIC) population consisting of 276 accessions genotyped by a 430 K SNP array. In this study, we detected the leaf starch content of tobacco plants cultivated in two places (Zhucheng and Chenzhou), which showed a wide variation of starch content in the population. A total of 28 and 45 significant single-nucleotide polymorphism (SNP) loci associated with leaf starch content were identified by single-locus and multi-locus GWAS models, respectively, and the phenotypic variance explained by these loci varied from 1.80 to - 14.73%. Furthermore, among these quantitative trait loci (QTLs), one SNP, AX-106011713 located on chromosome 19, was detected repeatedly in multiple models and two environments, which was selected for linkage disequilibrium (LD) analysis to obtain the target candidate region. Through gene annotation, haplotype, and gene expression analysis, two candidate genes encoding E3 ubiquitin-protein ligase (Ntab0823160) and fructose-bisphosphate aldolase (Ntab0375050) were obtained. Results showed that the variety carrying the beneficial alleles of the two candidate genes had higher gene expression level and leaf starch content, suggesting the potential role of candidate genes in enhancing the level of tobacco leaf starch content. Furthermore, silencing of Ntab0823160 in tobacco leaves reduced the content of total starch to 39.41-69.75% of that in the wide type plants. Taken together, our results provide useful resources for further investigation of the starch metabolic pathway and are also beneficial for the creation of eco-friendly cultivars with increased accumulation of leaf starch content.
淀粉是植物中一种重要的初级代谢物，可以为燃料乙醇生产提供生物能。许多研究都集中在拟南芥、玉米和水稻的淀粉代谢上，但关于烟草叶片淀粉含量的报道很少。因此，为了鉴定与烟草叶片淀粉含量相关的标记-性状关联和分离候选基因，利用包含 276 个系谱的多亲本高级世代互交（MAGIC）群体，通过 430K SNP 芯片进行了全基因组关联研究（GWAS）。在这项研究中，我们检测了在两个地方（诸城和郴州）种植的烟草植株的叶片淀粉含量，发现群体中的淀粉含量存在广泛的变化。通过单基因座和多基因座 GWAS 模型，分别检测到与叶片淀粉含量相关的 28 个和 45 个显著单核苷酸多态性（SNP）位点，这些位点解释的表型方差从 1.80 到-14.73%不等。此外，在这些数量性状位点（QTL）中，一个 SNP，AX-106011713，位于 19 号染色体上，在多个模型和两个环境中被重复检测到，该 SNP 被选择进行连锁不平衡（LD）分析，以获得目标候选区域。通过基因注释、单倍型和基因表达分析，获得了两个候选基因，分别编码 E3 泛素蛋白连接酶（Ntab0823160）和果糖-1,6-二磷酸醛缩酶（Ntab0375050）。结果表明，携带这两个候选基因有利等位基因的品种，其基因表达水平和叶片淀粉含量更高，表明候选基因在提高烟草叶片淀粉含量方面具有潜在作用。此外，在烟草叶片中沉默 Ntab0823160 可使总淀粉含量降低到野生型植物的 39.41-69.75%。综上所述，本研究结果为进一步研究淀粉代谢途径提供了有用的资源，也有利于创造具有更高叶片淀粉含量的环保型品种。
