Flooding tolerance and cell wall alterations in maize mesocotyl during hypoxia.

ABSTRACT - This research aimed to characterize the tolerance to flooding and alterations in pectic and hemicellulose fractions from mesocotyl of maize tolerant to flooding when submitted to hypoxia. In order to characterize tolerance seeds from maize cultivars Saracura BRS-4154 and BR 107 tolerant and sensitive to low oxygen levels, respectively, were set to germinate. Plantlet survival was evaluated during five days after having been submitted to hypoxia. After fractionation with ammonium oxalate 0.5% (w/v) and KOH 2M and 4M, Saracura BRS-4154 cell wall was obtained from mesocotyl segments with different damage intensities caused by oxygen deficiency exposure. The cell wall fractions were analyzed by gel filtration and gas chromatography, and also by Infrared Spectrum with Fourrier Transformation (FTIR). The hypoxia period lasting three days or longer caused cell lysis and in advanced stages plant death. The gelic profile from pectic, hemicellulose 2M and 4M fractions from samples with translucid and constriction zone showed the appearance of low molecular weight compounds, similar to glucose. The main neutral sugars in pectic and hemicellulose fractions were arabinose, xilose and mannose. The FTIR spectrum showed a gradual decrease in pectic substances from mesocotyl with normal to translucid and constriction appearance respectively RESUMO - Objetivou-se caracterizar a tolerancia ao alagamento e alteracoes nas fracoes pecticas e hemicelulosicas de mesocotilos de milho submetidos a hipoxia. Sementes de milho cultivar Saracura BRS-4154 e BR 107, tolerante e sensivel a hipoxia, respectivamente, foram submetidas a germinacao e a sobrevivencia das plantulas em condicoes de hipoxia, foi avaliada durante cinco dias. O material de parede celular, obtido de segmentos de mesocotilos da cultivar Saracura BRS-4154 com diferentes intensidades de danos causados por hipoxia, foi submetido a fracionamento com oxalato de amonio 0,5% e KOH 2M e 4M. As fracoes de parede celular obtidas foram analisadas por cromatografia em gel, cromatografia gasosa e espectro de infravermelho com transformacao dos dados pela serie de Fourrier (FTIR). Periodos de hipoxia superiores a tres dias causaram a lise celular (aparencia translucida),e, em estadios mais avancados, a morte das plantas. O perfil gelico das fracoes pecticas, hemicelulose 2M e 4M das amostras de mesocotilos translucidos e com constricao apresentaram compostos de baixos pesos moleculares semelhantes a glicose. Os principais acucares neutros nas fracoes pecticas e hemicelulosicas foram arabinose, xilose e manose. O espectro de FTIR mostrou um decrescimo gradual nas substancias pecticas do mesocotilo com aparencia normal, para translucido e constricao respectivamente.

Bibliographic Details

Main Authors:	VITORINO, P. G., ALVES, J. D., MAGALHAES, P. C., MAGALHAES, M. M., LIMA, L. C. O., OLIVEIRA, L. E. M. de
Other Authors:	PAULO CESAR MAGALHAES, CNPMS.
Format:	Artigo de periódico biblioteca
Language:	English eng
Published:	2001-11-01
Subjects:	Substancias pecticas, Maize, Pectic substances., Hemicelulose, Milho, Zea Mays., hemicellulose.,
Online Access:	http://www.alice.cnptia.embrapa.br/alice/handle/doc/485067
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