Novel temporal, fine‐scale and growth variation phenotypes in roots of adult‐stage maize (Zea mays L.) in response to low nitrogen stress

ABSTRACT There is interest in discovering root traits associated with acclimation to nutrient stress. Large root systems, such as in adult maize, have proven difficult to be phenotyped comprehensively and over time, causing target traits to be missed. These challenges were overcome here using aeropo...

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Published in:	Plant, cell and environment Vol. 34; no. 12; pp. 2122 - 2137
Main Authors:	GAUDIN, AMELIE C. M., MCCLYMONT, SARAH A., HOLMES, BRIDGET M., LYONS, ERIC, RAIZADA, MANISH N.
Format:	Journal Article
Language:	English
Published:	Oxford, UK Blackwell Publishing Ltd 01-12-2011 Blackwell
Subjects:	aeroponics architecture Biological and medical sciences Biomass corn crown root Fundamental and applied biological sciences. Psychology lateral root Nitrogen - metabolism Phenotype Plant Roots - growth & development Plant Roots - physiology root hair second‐order lateral root stochastic variation Time Factors Zea mays - genetics Zea mays - growth & development Zea mays - physiology Second order Monocotyledones Zea mays Architecture Root stochastic variation Lateral corn Root hair Plant ecology Variations Nitrogen lateral root second-order lateral root Cereal crop Stress Response aeroponics Phenotype Gramineae Aeroponic cultivation Angiospermae Spermatophyta crown root
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Summary:	ABSTRACT There is interest in discovering root traits associated with acclimation to nutrient stress. Large root systems, such as in adult maize, have proven difficult to be phenotyped comprehensively and over time, causing target traits to be missed. These challenges were overcome here using aeroponics, a system where roots grow in the air misted with a nutrient solution. Applying an agriculturally relevant degree of low nitrogen (LN) stress, 30‐day‐old plants responded by increasing lengths of individual crown roots (CRs) by 63%, compensated by a 40% decline in CR number. LN increased the CR elongation rate rather than lengthening the duration of CR growth. Only younger CR were significantly responsive to LN stress, a novel finding. LN shifted the root system architectural balance, increasing the lateral root (LR)‐to‐CR ratio, adding ∼70 m to LR length. LN caused a dramatic increase in second‐order LR density, not previously reported in adult maize. Despite the near‐uniform aeroponics environment, LN induced increased variation in the relative lengths of opposing LR pairs. Large‐scale analysis of root hairs (RHs) showed that LN decreased RH length and density. Time‐course experiments suggested the RH responses may be indirect consequences of decreased biomass/demand under LN. These results identify novel root traits for genetic dissection. The fine‐scale effects of low nitrogen stress on adult‐stage maize roots has not been fully characterized. Aeroponics, a system where roots grow in the air misted with a nutrient solution, was used for this analysis. The results show that low nitrogen impacts the adult maize root system at all scales of development including crown roots, first and second order lateral roots and root hairs, identifying novel traits for genetic dissection.
Bibliography:	ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23
ISSN:	0140-7791 1365-3040
DOI:	10.1111/j.1365-3040.2011.02409.x