论文部分内容阅读
Sugars in plants,derived from photosynthesis,act as substrates for energy metabolism and the biosynthesis of complex carbohydrates,providing sink tissues with the necessary resources to grow and to develop.In addition,sugars can act as secondary messengers,with the ability to regulate plant growth and development in response to biotic and abiotic stresses.Under phosphorus(P)starvation,plants accumulate sugars and starch in their leaves.Sucrose transporters(SUTs)play important roles in regulating the partition of sucrose in the intracellular,particularly between the vacuole and cytoplasm.It is unclear whether changes in sucrose supply to the root precede transcriptional and morphological responses to P starvation.One full-length cDNA that encode the wheat(Triticum aestivum L.)sucrose transporter gene(TaSUT 1A)were isolated from the young leaves of cv.Shijiazhuang8.The transformants for TaSUT1A gene in wheat were produced by a particle bombardment-mediated transformation method,and transcripts of TaSUT1A gene accumulated at higher levels in leaves and in roots of primary transgenic plants.We then investigated the changes in sucrose delivery to the root in response to P starvation and their impact on biomass partitioning,gene expression,and root morphology in TaSUT1A overexpressing wheat lines.Our results indicated an increased metabolic level in TaSUT1A-overexpressed plants,which showed higher total soluble sugars concentrations and sucrose concentrations in leaf and root under low and normal P supply levels.Moreover,increase in the biomass of root,sucrose content in root and total phosphorus content in the whole plant were observed in the transgenic lines under low phosphorus supply levels.The root elongation and root surface area of TaSUT1A-overexpressed plants were increased by 24.1-39.5%and 27.8-41.9%relative to wild-type controls under P starvation.The increased phosphorus uptake under P starvation may have resulted from the fact that the overexpression of TaSUT1A in transgenic wheat plants stimulated root development and increased the partition of sucrose from leaves to roots.Our results suggest that TaSUT1A plays essential roles in root development and in phosphorus usage in wheat.Further,our results provide new knowledge and valuable gene resources that should be useful in efforts to breed crops targeting high yield with less fertilizer input