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Abstract Detail


Secondary Metabolism

Echeverry-Solarte, Morgan [1], Figueroa, Annette [2], Siritunga, Dimuth [2].

Expression Quantification of Genes Associated with Cyanogenic Glucosides in Cassava.

Cassava (Manihot esculenta Crantz) has cyanogenic glycosides in its roots and leaves. These compounds function in plants as protective agents against herbivores as well as the translocable form of reduced nitrogen. For this reason, cassava foods must be processed to remove cyanogens prior to consumption. The genes involved in the cyanogenic pathway, CYP79D1, CYP79D2, linamarase, alpha-hydroxynitrile lyase (HNL) and beta-cyanoalanine synthase (b-CAS) have been identified, though very little is known regarding their transcriptional regulation. Our work aimed to identify the differential expression of these genes using Real-Time PCR. Bioinformatics analysis allowed the design of gene specific primers. Conventional PCR and Real-Time PCR (with SYBR Green ® as fluorochrom) was developed using cDNA from leaves and roots of three varieties of cassava: Mcol 2215 (low cyanide), TMS 60444 (intermediate cyanide), and Mtai16 (high cyanide) grown under in vitro conditions. The statistical analysis of the results show differential expression of these genes between leaves and roots, consistent with the model that cyanogens, synthesized predominantly in the leaves, are transported to the roots where it is converted to asparagine. This conversion is due to the presence of equal or higher levels of b-CAS in the root than leaves in cassava, while HNL and linamarase are at negligible levels in the roots. This demonstrates that cyanogens have an important function as a source of mobile reduced nitrogen to the plant. We will also present data on the expression pattern of the above mentioned genes in the presence of different concentration of reduced nitrogen in the media.


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1 - University of Puerto Rico Mayaguez, Department of Biology, PO Box 9012, Mayaguez, PR, 00680, USA
2 - University of Puerto Rico Mayaguez, Department of Biology

Keywords:
cassava
gene expression
cyanide.

Presentation Type: Plant Biology Abstract
Session: P
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM
Number: P20043
Abstract ID:1696


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