Farming Systems Research at the International Agricultural Research Centers

Final report of the Review of Farming Systems Research at CIAT, ICRISAT, IITA, and IRRI prepared by a team consisting of John Dillon, Donald Plucknett, and Guy Vallaeys. It also contains the proceedings of a May 1978 Workshop on Farming Systems Research in Nairobi based on the stripe review's analysis. This is the first CGIAR "stripe review," in which a particular topic common to a number or all the IARCs is examined. This was an agenda document at TAC Eighteen in February and TAC Nineteen in June, 1978, and at the CGIAR meeting in November 1978

Development and Extension of Agricultural Production Technology

The discussion in the previous chapters makes it clear that the environment for technological change in agriculture is highly variable across ecological regions and policy systems and is frequently exceedingly complex. Generally, the problems of technological change are especially intractable in the semiarid areas but also are acute in the lowland humid tropics. Research to date has perhaps been most successful in the high-potential areas of the high-altitude plateaus and irrigated zones, which account for a very small percentage of total cropped area in the region. Yet even here, major problems remain on the institutional side to insure a steady flow of appropriate innovations to a dynamic agriculture.PRIFPRI

Gene tfd from the 2,4-D degrading bacteria Alcaligenes paradoxus TV1 could be used as probe for the research of soil microorganisms able to degrade this herbicide

International audienc

Pesticides: Microbial degradation and effects on microorganisms

57 ref. chap. 18International audienc

Isolation of a large plasmide from a 2,4-D degrading strain of alcaligenes paradoxus carrying the genes involved in 2,4-D degradation

International audienc

Mise en evidence et etude de l'activite d'une communaute microbienne degradant le 2,4-D

National audienc

The metabolic pathway of 2,4-dichlorophenoxyacetic degradation involves different families of tfdA genes according to PCR-RFLP analysis

International audienc

The use of TFDA and TFDC genes from Alcaligenes euthrophus JMP134 AS probes in colony hybridisation analysis to assess diversity of 2,4-D degrading bacteria in soil

*INRA Laboratoire de microbiologie des sols BP 86510 21065 Dijon cedex (FRA) Diffusion du document : INRA Laboratoire de microbiologie des sols BP 86510 21065 Dijon cedex (FRA)International audienc

La diversité des gènes impliqués dans la dégradation de l'acide 2,4-dichlorophénoxyacétique illustre-t-elle une facilité de la microflore à s'adapter à de nouveaux substrats?

National audienc

The metabolic pathway of 2,4-dichlorophenoxyacetic acid degradation involves different families of tfdA and tfdB genes according to PCR-RFLP analysis

International audienceTwenty-five 2,4-dichlorophenoxyacetic acid (2,4-D) degrading bacteria from geographically diverse locations and presenting various degrees of similarity or no similarity to the tfdA and tfdB genes from Alcaligenes eutrophus JMP134 were analysed by PCR-RFLP (restriction length fragment polymorphism). Primers for the 2,4-D etherase gene were derived by sequence alignment of the tfdA genes from A. eutrophus JMP134 and Burkholderia sp. RASC. Primers for the 2,4-dichlorophenolhydroxylase gene were based on the tfdB gene sequence from A. eutrophus JMP134 by taking codon degeneration and variations in amino acid residue sequences into consideration. PCR amplification using the tfdA primer set produced fragments of 0.3 kb from 17 strains which showed varying degrees of similarity to the tfdA gene probe from A. eutrophus JMP134. Significant variations in the gene sequences were confirmed by PCR-RFLP analysis. DNA amplification using the tfdB primer set produced a 1.1 kb fragment from 19 strains. Amongst them, two did not show any similarity to the tfdB gene probe. The size and restriction pattern of the products obtained from A. eutrophus JMP134 were in accordance with the expected size calculated from the A. eutrophus tfdA and tfdB gene sequence and their theoretical PCR-RFLP patterns. Some strains which did not amplify using the tfdA primer set did however amplify with the tfdB primer set. These results suggest the independent evolution of these two genes in the construction of the 2,4-D metabolic pathway. Our tfdA and tfdB primer sets could be used for the detection of similar sequences in bacteria and soils. Moreover, PCR-RFLP patterns could also be used to select subsets of strains for sequencing to study the phylogeny of the tfdA and tfdB genes