marker-assisted selection in wheat

18Marker-assisted selection – Current status and future perspectives in crops, livestock, forestry and fishTable 1Number of research initiatives utilizing genetic markers in the crop and forestry sectors sorted bytype of markersMarkers Crop Forestry TotalRFLP 61 9 70RAPD 158 15 173SSRs/Microsatellites 68 19 87AFLP 65 3 68Isozymes 2 50 52Chloroplast DNA markers 0 11 11rDNA (ribosomal DNA sequences) 0 4 4Other or not specified 135 77 212Total 489 188 677Table 2Number of research initiatives utilizing genetic markers in the crop and forestry sectors according tothe development stage of the technique or productPhase Crop Forestry TotalExperimental phase 344 179 523Field tests 107 8 115Commercial phase 4 1 5Unspecified 34 0 34Total 489 188 677consulted (for a complete description seeFAO, 2005). In particular, information onplant biotechnology products and techniqueswas gathered from a survey undertakenin Latin America by the InternationalService for National Agricultural Research(ISNAR) and from country biotechnologystatus assessment reports prepared forFAO in South and Southeast Asia, Africaand transition countries in Eastern Europe.Other information was obtained fromcountry reports and published literature.The initial biotechnology applicationdata obtained was classified on a country/regional/continental basis, by species, traitanalysed or technique used, and by whetherthe application was in the research or fieldtesting phases or was already commerciallyreleased.FAO-BioDeC currently contains677 entries related to the use of molecularmarker techniques, 489 of which areassociated with crop plants and 188 withforest trees. Table 1 suggests that earlygeneration DNA-based molecular markerssuch as randomly amplified polymorphicDNAs (RAPDs) are more widely used thanthe more recently developed markers, e.g.amplified fragment length polymorphisms(AFLPs), while isozymes are still largelyused in the forestry sector.Only in five cases have the research initiativesreported reached the final stage ofdevelopment, giving rise to commercializedproducts (Table 2). These are one variety ofan unspecified ornamental plant released inBrazil; one variety of rice commercializedin Indonesia; one strain of Rhizobium etli,the soil bacterium inducing the formationof nitrogen-fixing nodules on the roots ofa common bean obtained in Mexico; onerice variety containing pyramided genes forbacterial leaf blight resistance obtained inthe Netherlands Antilles; and one varietyof an unspecified forest tree in Burundi. In115 cases (107 in the crop sector and eight