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).