Towards incorporating the biosynthetic transformation required for Striga inhibition from Desmodium into edible legume intercrops

Lead Research Organisation: Rothamsted Research
Department Name: Unlisted

Abstract

The aim of this project is to identify the C-glycosyltransferases responsible for the biosynthesis of isoschaftoside, a C-glycosylflavone isolated from Desmodium uncinatum responsible for interfering with the development of the parasitic weed Striga hermonthica on maize.

Specific objectives are;
1. Prepare substrates to identify CGT activity. The chemical preparation of putative intermediates in the pathway to isoschaftoside will be performed. Glucosyl donors that are not commercially available will also be prepared.

2. The metabolome of D. uncinatum and D. intortum roots and root cultures and the root materials of, V. unguiculata, L. japonicus and M. truncatula metabolome will be examined for compounds arising from CGT transformations and to determine the extent that the biosynthetic pathway to isoschaftoside is present.

3. Determine the CGT activity in plant tissues of desmodium and genome-sequenced legumes. The protein extracts will be assayed for the downstream biochemical conversion of intermediates prepared in Objective 1 in the biosynthetic pathway of isoschaftoside to identify the glycosylated substrate and glycosyl donor.

4. Obtain CGT amino acid sequence data. The protein will be analysed by MALDI-TOF mass spectroscopy and Q-TOF mass spectrometry. Partial amino acid sequences will be identified in this fashion, and homologous protein sequences searched for.

5. Identify CGT gene sequence, clone and functionally express. Candidate genes can be expressed in E. coli and these protein products then assayed for CGT activity.

6. Identify legumes that interfere with striga development. The CGT gene also provides the basis for future genetic transformation of cowpea to directly transfer the striga protection mechanism from desmodium.

Publications

10 25 50