To investigate the function of PsnSWEET7 in nitrogen response and regulation of carbon and nitrogen metabolism,the transgenic lines overexpressing PsnSWEET7 were generated in Populus simonii × P. nigra via Agrobacterium-mediated transformation. The effects of this gene on plant growth and carbon-nitrogen metabolism were investigated by subcellular localization and phenotype analysis,as well as determinations of physiological indices and gene expression under treatments with different concentrations of ammonium nitrate (NH4NO3). The PsnSWEET7 protein was localized to the plasma membrane. Under NH4NO3 treatments,compared with the wild type,the plant height and ground diameter of PsnSWEET7 overexpressing plants increased by 17.3% and 17.8%,respectively(P<0.05);the mass fractions of sucrose,glucose,soluble protein and free amino acids in stems increased by 20.1%,25.4%,9.3% and 7.5%,respectively(P<0.05);the cellulose mass fraction increased by 10.5%(P<0.05),while the lignin mass fraction decreased by 12.2%(P<0.05). Under normal and high nitrogen conditions,the activities of vacuolar invertase and cell wall invertase were significantly elevated in transgenic plants. This study indicates that PsnSWEET7 can remodel the carbon and nitrogen metabolism of P.simonii×P. nigra by regulating sugar transport,thereby promoting plant growth,and provides new genetic resources and theoretical basis for the molecular breeding of high-yield and high-quality poplars.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |