Nitrogen-source preference in blueberry (Vaccinium sp.): Enhanced shoot nitrogen assimilation in response to direct supply of nitrate

摘要: Blueberry (Vaccinium sp.) is thought to display a preference for the ammonium (NH4+) form over nitrate (NO3-) of inorganic nitrogen (N). This N-source has been associated with generally low capacity assimilate NO3- N, especially within shoot tissues. Nitrate assimilation mediated by reductase (NR), rate limiting enzyme that converts nitrite (NO2-). We investigated potential limitations in two blueberry species, rabbiteye ashei) and southern highbush corymbosum) supplying roots, leaf surface, or through cut stem. Both species displayed relatively but similar root uptake rates both forms N. roots transiently increased NR activity up 3.3-fold gene expression 4-fold. However, did not increase its transport xylem, nor it leaves, indicating acquired N was largely assimilated stored roots. Foliar application 3.5-fold, alter metabolism-related expression, suggesting blueberries are capable post translational regulation shoots. Additionally, ends stems resulted around 5-fold activity, 10-fold transcript accumulation, 195-fold accumulation NITRITE REDUCTASE (NiR1) which codes catalyzing conversion NO2- NH4+. These data indicate shoots assimilating when directly supplied these Together, suggest translocation may limit overall blueberry.