Abstract
Plant utilizes nitrate and/or ammonia as nutrient. There are plant species having preference to nitrogen sources: rice likes ammonia whereas cucumber prefers to nitrate. We consider that such preference arises from the different rate of nitrite uptake by chloroplast. We cloned a cDNA, CsNitr1, which encodes a putative nitrite transporter of chloroplast envelope in cucumber leaves and introduced it into rice (Oryza sativa L. cv. Nipponbare) to modify the transport process of nitrite in the nitrate assimilation pathway.
Transgenic rice grew hydroponically with nitrate or nitrite as well as non-transformed rice with ammonia. However, the latter died after the replacement to new hydroponic medium that contained nitrate as a sole nitrogen source. Uptake of nitrate by the transgenic rice was higher than that by non-transformed ones indicating that the metabolic speed of rice for nitrate could be improved by the introduction of CsNitr1.
