Development of reproductive structures
Up to now, two nitrate transporters have been shown to be of importance
in silique and seeds: NPF2.12/NRT1.6, and NPF5.5. NPF2.12/NRT1.6 is
capable of transporting both nitrate and gibberellin
GA1/3, and is expressed intensively in funiculus
vascular bundles, which are mostly made of phloem tissue inArabidopsis (Almagro, Lin, & Tsay, 2008). InNPF2.12/NRT1.6 mutants, mature seeds contain effectively less
nitrate, suggesting that NPF2.12/NRT1.6 is involved in transporting
nitrate from maternal tissue to the developing embryo via the phloem
(Almagro et al., 2008). NPF5.5, which as been shown to transport
nitrate, is involved in controlling embryo N content: in knock-out
mutants, embryos at the bent cotyledon stage have a 7-8% reduction in
the N content suggesting that the import of nitrate to the developing
seed has been impacted (Léran et al., 2015).