Hu Zheng-Yu, He Pei-Xin, Li Yu-Jie, Liu Hong-Juan, Ahmad Rafiq, Ali Izhar, Si Cheng-Cheng
School of Tropical Agriculture and Forestry and Sanya Institute of Breeding and Multiplication, Hainan University, Haikou, 570228, China.
Hainan Seed Industry Laboratory, Sanya, 572025, China.
BMC Plant Biol. 2025 Mar 4;25(1):281. doi: 10.1186/s12870-025-06295-2.
Invertases (INVs) included CWIN, CIN and VIN, are key enzymes in sucrose hydrolysis into glucose and fructose and essential for plant root development. Yet the effects of nitrogen and planting density on IbINVs expression remains unexplored in sweetpotato.
This study identified 22 invertase (IbINV) genes in the sweetpotato genome and conducted comprehensive analyses of their subcellular localization, gene structure, and conserved motifs and domains. Gene Ontology functional and protein interaction network analysis suggested that IbCWIN1/2/5/6 potentially interact with HKL1/3, HXK2/3/4, and other proteins, significantly influencing carbohydrate metabolic functions and biological processes in sweetpotato. Transcriptome data revealed that IbCIN2 and IbVIN3 were highly expressed in fibrous root (FR) and potential storage root (PSR), while IbVIN4 exhibited high expression levels in storage roots (SR), and IbCWIN2 was highly expressed in both FR and SR. Moreover, the field experiments demonstrated that, compared with EN (180 kg N ha) combined with LD (50,000 plant ha), MN (120 kg N ha) combined with MD (62,500 plant ha) enhanced storage roots number and weight. Notably, compared with LDEN treatment, IbCIN2, IbCWIN2, IbVIN3 and IbVIN4 under MDMN treatment were significantly upregulated, extremely significant differences at 15DAP, of which IbCIN2 showed a maximum of 23.24-fold change, showing a positive correlation with increased INV enzyme activity, glucose (GLc), and fructose (FRc) content. Additionally, screening of homologous genes showed that IbCIN2 is homologous to AtA/N-INVI and AtA/N-INVG, IbCWIN2, IbVIN3 and IbVIN4 are homologous to VACUOLAR, INVERTASE1 and BFRUCT4, with similar functions, further supporting their involvement in storage root formation and development.
These observations underscore the expansion of IbINVs in sweetpotato and provide a theoretical basis for optimizing the interaction between nitrogen application and planting density in sweetpotato, allowing for more efficient nitrogen use and improved growth.
转化酶（INVs）包括细胞壁转化酶（CWIN）、细胞质转化酶（CIN）和液泡转化酶（VIN），是蔗糖水解为葡萄糖和果糖的关键酶，对植物根系发育至关重要。然而，氮素和种植密度对甘薯中IbINVs表达的影响尚未得到研究。
本研究在甘薯基因组中鉴定出22个转化酶（IbINV）基因，并对其亚细胞定位、基因结构、保守基序和结构域进行了综合分析。基因本体功能和蛋白质相互作用网络分析表明，IbCWIN1/2/5/6可能与HKL1/3、HXK2/3/4和其他蛋白质相互作用，显著影响甘薯的碳水化合物代谢功能和生物学过程。转录组数据显示，IbCIN2和IbVIN3在须根（FR）和潜在贮藏根（PSR）中高表达，而IbVIN4在贮藏根（SR）中表达水平较高，IbCWIN2在FR和SR中均高表达。此外，田间试验表明，与高氮（180 kg N ha）结合低密度（50,000株 ha）处理相比，中氮（120 kg N ha）结合中密度（62,500株 ha）处理增加了贮藏根的数量和重量。值得注意的是，与低密度高氮处理相比，中密度中氮处理下的IbCIN2、IbCWIN2、IbVIN3和IbVIN4显著上调，在块根膨大15天时差异极显著，其中IbCIN2变化倍数最大，为23.24倍，与转化酶活性、葡萄糖（GLc）和果糖（FRc）含量的增加呈正相关。此外，同源基因筛选表明，IbCIN2与AtA/N-INVI和AtA/N-INVG同源，IbCWIN2、IbVIN3和IbVIN4与液泡转化酶1和BFRUCT4同源，功能相似，进一步支持它们参与贮藏根的形成和发育。
这些观察结果强调了甘薯中IbINVs的扩展，并为优化甘薯施氮量与种植密度之间的相互作用提供了理论依据，从而实现更高效的氮素利用和更好的生长。
