Data/hora: 29/06/2024 10:30:47

Biblioteca(s): 	Epagri-Sede.	
Data corrente: 	18/02/2016	
Data da última atualização: 	18/02/2016	
Autoria: 	LAVINSKI, A. O.; DETMANN, K. C.; SANGLARD, L. M. V.; RODRIGUES, F. A.; ARAUJO, L.; RIBEIRO, D. M.; ARAÚJO, W. L.; MATTA, F. M.	
Título: 	SILICON ENHANCES ROOT DIAMETER AND AERENCHYMA FORMATION AND INDUCES CHANGES IN METABOLISM AND FERMENTATIVE PATHWAY IN WATERLOGGED RICE PLANTS VIA ETHYLENE-SIGNALING PATHWAYS.	
Ano de publicação: 	2015	
Fonte/Imprenta: 	In: BRAZILIAN CONGRESS OF PLANT PHYSIOLOGY, 15., 2015, Foz do Iguaçu, Paraná, Brazil . Annals... Rio Claro, SP: SBFV, 2015.	
Idioma: 	Inglês	
Conteúdo: 	In stagnant culture solutions, we have previously identified altered morphology of roots (i.e., 
thicker  and  shorter  roots)  of  rice  (Oryza  sativa  L.)  plants  when  supplemented  with  silicon 
(Si).  Here,  we  hypothesized  that  Si  may  exert  its  effects  on  root  morpho-anatomical  traits 
through a ethylene signaling pathways. To clarify the relationship between Si and root traits 
we  first  conducted  a  root  structural/anatomical  characterization  of  rice  plants  supplemented 
with Si and then the underlying mechanisms were investigated  by combining hormonal and 
metabolite profiles with expression of a range of genes presumably affected by ethylene. Si 
addition did not alter root biomass, but led to decreases in root length together with increased 
root  diameter.  In  +Si  plants,  there  was  a  geater  suberization  of  schlerenchyma  and 
lignification of the endodermis and exodermis, whereas in  ?Si plants differential lignification 
was only observed in the exodermis. Si was also associated with remarkable increases in the 
cross-sectional  areas  of  vasculature  (93%),  xylem  vessels  (50%),  cortex  (92%)  and 
particularly  aerenchyma  (448%).  Relative  to  ?Si  plants,  their  +  Si  counterparts  displayed 
lower  (80%)  concentration  of  ACC  (the  immediate  ethylene  precursor)  in  parallel  to 
remarkable  higher  concentrations  of  ethylene  (600%),  salicylic  acid  (300%)  and  jasmonic 
acid  (2500%),  whereas  the  pools  of  indol-3-acetic  acid  (auxin)  and  abscisic  acid  were 
unresponsive to Si. In the +Si plants, we observed a global up-regulation of transcripts from 
genes associated with ethylene biosynthesis (in some cases exceeding 200 times, e.g., ACC 
oxidase and the homologue for ACC synthase). Overall, Si nutrition caused an up-regulation 
of a range of genes associated with synthesis of lignin and suberin and genes associated  with 
acclimation  responses  of  rice  to  submergence  whose  expressions  are  triggered  by  ethylene, 
with significantly higher abundance for  Sub1B  (10 fold) and  SK1  (100 fold). Overall, Si did 
not affect the root levels of sugars, but it reduced the levels of organic acids associated with 
the  tricarboxylic  acid  cycle  and  increased  a  range  of  amino  acids.  Our  data  suggest  an 
upregulation  of  fermentative  pathway,  in  line  with  an  up-regulation  of  genes  encoding  for 
enzymes related to the anaerobic pathway. However,  increases in fermentative pathway seem 
not to be associated with hypoxic conditions but they could simply be an additional route to
supply  energy  that  is  required  for  several  energy-consuming  processes  that  seem  strongly 
upregulated in the +Si plants such  as biosynthesis of cell wall components. In summary, Si 
apparently triggers ethylene production which in turn seems to induce a range of molecular 
and metabolic alterations that culminate with the observed changes in root anatomy upon Si 
supplementation.	
Palavras-Chave: 	Flooding; Gene expression; Rice; Silicon.	
Categoria do assunto: 	F Plantas e Produtos de Origem Vegetal	
URL: 	http://intranetdoc.epagri.sc.gov.br/producao_tecnico_cientifica/DOC_36879.pdf	
Registro original: 	Epagri-Sede (Epagri-Sede)	
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