S5-06
A New Gene from Cassava
Storage Roots Related to Secondary Xylem
de
Souza C.RB, E.R.P. de Almeida, L.J.C.B. Carvalho and E.S. Gander
EMBRAPA-Genetic
Resources and Biotechnology, CP 02372, CEP 70770-900 Sain Parque
Rural, Brazilia, Brazil carvalho@cenargen.embrapa.br
The
compartmentalization model of storage root (SR) of cassava considers the
central cylinder a tissue system composed of vessels and store
parenchyma cells with varying proportion from the outside to the inside
SR diameter. Each cell
complex component has its proper developmental fate maturing inward.
To isolate genes developmentally regulated in this system we used
our previously isolated 17 kDa unknown protein to isolate its
corresponding gene with PCR, and analysis with MALDI-TOF, BLAST query
search, gene expression and genomic restriction digestion analysis.
This strategy allowed us to isolate a cDNA clone with ORF of 531
bp which codes for a 177aa protein.
The deduced protein is rich in glutamic acid (30%) and showed
identity of 48% with root nodule protein ag13
and HEV-B5 from rubber tree. The
MALDI-TOF analysis identified peptides of 16 kDa and 18kDa mass
indicating a postranslational modification of this gene product.
Total RNA blot analysis showed specificity to a gene expressed in
vessels as indicated by weak hybridization with rich parenchyma cells
tissue. The hybridization signal of the RNA blot of parenchyma cell
zones increased from the outer layer of the central cylinder of the SR
to the inner layer. The gene also showed as a single copy gene in the
cassava genome. Full gene
structure and mapping in the cassava genome is in progress.
This research financed by: National Biotechnology Program (EMBRAPA), and
National Research Council (CNPq).
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