CBN-V Video Archives - 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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