e-journal

Auxin distribution is differentially affected by nitrate in roots of two rice cultivars differing in responsiveness to nitrogen

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Background and Aims:
Although ammonium (NH4+) is the preferred form of nitrogen over nitrate (NO3-) for rice (Oryza sativa), lateral root (LR) growth in roots is enhanced by partial NO3- nutrition (PNN). The roles of auxin distribution and polar transport in LR formation in response to localized NO3- availability are not known.
Methods:
Time-course studies in a split-root experimental systemwere used to investigateLRdevelopment patterns, auxin distribution, polar auxin transport and expression of auxin transporter genes in LR zones in response to localized PNN in ‘Nanguang’ and ‘Elio’ rice cultivars, which show high and low responsiveness to NO3+, respectively. Patterns of auxin distribution and the effects of polar auxin transport inhibitors were also examined in DR5::GUS transgenic plants.
Key Results:
Initiation of LRs was enhanced by PNN after 7 d cultivation in ‘Nanguang’ but not in ‘Elio’. Auxin concentration in the roots of ‘Nanguang’ increased by approx. 24 % after 5 d cultivation with PNN compared
with NH4+ as the sole nitrogen source, but no difference was observed in ‘Elio’. More auxin flux into the LR zone in ‘Nanguang’ roots was observed in response to NO3+ compared with NH4+ treatment. A greater number of auxin influx and efflux transporter genes showed increased expression in the LR zone in response to PNN in
‘Nanguang’ than in ‘Elio’.
Conclusions:
The results indicate that higher NO3+ responsiveness is associated with greater auxin accumulation in
the LR zone and is strongly related to a higher rate of LR initiation in the cultivar ‘Nanguang’.

Key words: Auxin distribution, lateral root, nitrate, rice, Oryza sativa.

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Informasi Detail

Judul Seri

Annals of Botany

No. Panggil

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Penerbit

Oxford : Oxford University Press on behalf of the Annals of Botany Company., 2013

Deskripsi Fisik

Annals of Botany 112: 1383–1393, 2013

Bahasa

English

ISBN/ISSN

10958290

Klasifikasi

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Tipe Isi

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Tipe Media

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Tipe Pembawa

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Edisi

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Subjek

BIOLOGI

Info Detail Spesifik

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Pernyataan Tanggungjawab

agus

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