Variation for N Uptake System in Maize: Genotypic Response to N Supply

Trevor Garnett, Darren Plett, Vanessa Conn, Simon Conn, Huwaida Rabie, J. Antoni Rafalski, Kanwarpal Dhugga, Mark Tester, Brent Kaiser

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    19 Citations (Scopus)

    Abstract

    An understanding of the adaptations made by plants in their nitrogen (N) uptake systems in response to reduced N supply is important to the development of cereals with enhanced N uptake efficiency (NUpE). Twenty seven diverse genotypes of maize (Zea mays, L.) were grown in hydroponics for 3 weeks with limiting or adequate N supply. Genotypic response to N was assessed on the basis of biomass characteristics and the activities of the nitrate (NO3) and ammonium (NH+4) high-affinity transport systems. Genotypes differed greatly for the ability to maintain biomass with reduced N. Although, the N response in underlying biomass and N transport related characteristics was less than that for biomass, there were clear relationships, most importantly, lines that maintained biomass at reduced N maintained net N uptake with no change in size of the root relative to the shoot. The root uptake capacity for both NO3 and NH+4 increased with reduced N. Transcript levels of putative NO3 and NH+4 transporter genes in the root tissue of a subset of the genotypes revealed that predominately ZmNRT2 transcript levels responded to N treatments. The correlation between the ratio of transcripts of ZmNRT2.2 between the two N levels and a genotype's ability to maintain biomass with reduced N suggests a role for these transporters in enhancing NUpE. The observed variation in the ability to capture N at low N provides scope for both improving NUpE in maize and also to better understand the N uptake system in cereals.

    Original languageEnglish
    Article number936
    Number of pages13
    JournalFrontiers in Plant Science
    Volume6
    Issue numberNOVEMBER
    DOIs
    Publication statusPublished - 2015

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