«Biotechnology-Assisted Participatory Plant Breeding: Complement or Contradiction? PPB Monograph No. 3 Ann Mane Thro and Charlie Spillane 1 7 ...»
If su ccessfu l, this project will greatly enhance local control over planting material, increase the supply of improved materiaIs, ¡ncrease diversity and flexibility in !he local fanning system, stimulate ¡nterest in cassava R&D and enh ance their impac t, and serve as a model for other region s. The project will also c reate one of the ¡¡rst teams of biotechnologists trained to conduct participatory research with rt:source-poor fanners.
SO URCES: Thro e t al (1999b); J. Restrcpo (pers. comm.).
Biotechnology as a Ser of Tools lar Formal CU'ld Informal Plant Breeding
Farmer-led mlcropropagatloD oC potato In DaJat, Vietnam One well documented and orten cited example of successru l biotechnology· assisted participatory research la that or rarroers in Vietnam's Dalat province, who have used in vitro tissue culture methods ror commercial potato production.
In the early 198Os, clean potato planting materials were virtuaJly unobtainable in the major potato·producing region of the Dalat h ighlands.
Researchers responded by in troducing a system whereby farmen could maintain three newly selected cultivars as test tube potato plantlets and multiply them in vitro as well as by using cuttings. The in vitro propagation method u sed • relatively simple materials. including a small steam autoclave, a home·made inocu lum box, and a culture shetf with a fluorescent Iight and glass tubes. TIte cultivars were established in culture as molher planta, rrom which apical ahoots werc harvested continuously ror u p to 6 months. Aiter cutting the apical s hoots wt!re rooled in pollets. Two weeks ¡atee they were sold to other interested farmen or u sed for transplanting by (he rarmer, who produced cuttings. In 1982, over 2.8 million cuttings were sold to commerciaJ potato growers. Mter 4 years, all patatoes in the Dalat area were grown with this material. Growers keep lhe small tubers rrom the harvest for use as seed over two or three generations.
The advantages of this system are considerable. Farmers can produce highqulity planting materials themselves. and no longer need to import tuber seed from elsewhere. The system is cheaper than conventional multiplication, with rooted cuttings selling for U5$O.005 each. In addition, healthy stocks can be maintained indefmitely. 1( is thought that this system could be adapted to other locations around the world with similar environmental condition s.
A follow· up survey S years later suggested that fanners ' ¡nterest in this project had waned and that there were difficulties in initiating similar projects in Olher arcas of Vietnam. In 1993 it was noted th at only 3 out of 10 farrner micropropagation units were still functioning. Nevertheless, the system continued to supply an adequate amount or c1ean planting material to commercial growers in the DaJat area. It has now been mnnín g for nearly 20 years. A 1998 update confinned that most villagers found the tissue culture process too time·consuming, hut lhat one 'expert' fanner h ad continued and was selling plants to neighbors. In other words, a rural micro-enterpris e had developed.
SOURCES: Van Uyen and vander Zaag (1983, 1987); van Uyen (1984) ; 8roerse and v isser (l996); G. ?rain, L.T. Bin h (pers. comms.).
micropropagation h as been extended to other coun tries an d crops (Sasson, 1998; Bryan, 1988; vander Zaag et al, 1990).
Because of their relative simplicity, tiss ue culture services launched by formal researche rs can probably be trans ferred s u ccessfully to innovative farmers QVe r tirJLe, perha ps as a fo rm or micro·e nterprise development. Sorne fanners' organization s, especiaJly those organized Biotechnology-Assisled PPB: Complcmenl or Contradiction?
around commodities, may be able to establish and sustain tissue culture micro-enterprises which provide pla nting rnaterials not only to their members but also to a \Vider cirele in the local farming cornmunity. lo any event, increased farmer involvement in sorne or all of the tissue culture process scerns likely in the future.
There will, oC cou rse, also be constraints to [anner participation in tissue culture. These ¡nelude the need to provide training in tech nical and business skills, together with small amounts of capital to finance start-ups. However, the amouot of external support oeeded is sma ll compared to other biotechnologies. The FIDAR project in Colombia is experirnenting with the effectiveness of such s upport.
Many [actors, both cnvironmental and socio-economic, affect th e success of tissue culture operations in different arcas. For instance, low-technology operations have temperature needs that can be met less expeosively in a place like Dalat, in Vi etnam, where the clima te is mild, without extremes of heat or cold. Farmers in highland arcas with cooler clima tes may have a comparative ad vantage in providing virusfree planting materi al s of vegetatively-p ropagated crops to farmers in other arcas. 00 the socio-economic side, labor requirements, and especially the seasonal availability of labor, cou ld prove critical. No comprehensive studies to define the conditions that favor the establishment oC farmer-Ied tissue culture e nterpnses have yet been carried out. GIS could be used to identify possible areas where low-cost tissue culture may be possible.
Given its evident popularity, low ~ te c hoology tissue cul tu re could probably be integrated with PPB relatively easily in many developing countries. It could prove a valuable too! in speeding the delive ry of the products of PPB to farmers, thereby overcoming one of the severest and most universal constraints to the increased productivi ty oC re sourcepoor Carming systems.
5. Relevant Products from Biotechnology Research Biotechnology is nQW developing a wide range of products which, ir they can be incorporated into appropriate craps and varieties, are likely to be useful lo resource-poor farmers. TabIe 3 givcs sorne examples.
Access lo these technologies depends on the stage of the rescarch, the terms under which they might be made available, whether resources are provided for technology transfer. whethe r the tcchnology is durable enough for Cield use, and whether IPR or biosafcty restrictions apply.
Reaiatance to Peats and Diseases
Farmers expend considerable financial and labor resources in trying la counter the crap losses associated with diseases, inseet pests, and weeds. The management practices and chernical control of insects alone are estimatcd to cost around US$lO billion annually, yet the losses caused by insects still account for 20%-30% of glo bal crop production (Oerke and Dehne. 1997).
Much research effort has gone into developing crops with increased tolerance or resistance to pests and diseases. New resistance options emerging from biotechnology research may be able to supplernent the products developed through conventional breeding and the practices developed through IPM, leading to reduced pesticide and agrochemical use. For example, a recent survey of the adoption of insect resistantcotton in four states of the USA found that insecticide use h ad decreased significan tly while yields and profits had increased (Srnith and Heimlich, 1999, www.ers.usda.gov/whatsnewfissuesfgmo/). The potential of 'integrated transgenic crop management' to further reduce insecticide use has scarcely been explored.
(Ka nazin e t a l, 1996; Ghesquiere et al, 1997). It is becomi ng increasi..ngly feasible to use markers to select for these region s.
Alternatively, the u se of markers can be co mbined with th a t of transgenesis lo ¡sola te and tra n sfer th e functional genes from the clustcrs betwee n species (Mich elmore, 1995; Paterson, 1995; Hamilton, 1997). Sorne transgenic a pproaches are generatin g useful trait s that were previously not available or accessible.
Recent progress in under standing the genetics of plant disease resistancc has opened up a number of n ew avenues towards ge netically en gineered solutions. Genes co ntroUing race-specific and broad-spectrum resistance responses h ave been doned (van der Biezen and Jone s, 1998), allowing new induced resistance pat hways to be identificd (Hunt et al, 1996). Advances co n tin u e to be made in the identification of antifungal proteins, which inhibit either pathogen developmen t or thc accumula tion of mycotoxins. PPB programs facing continu in g problems with specific p ests or diseases m ay be able to make good u se of these new biotechnology approaches to control.
Breeding for insect resistance and the use of biocontrol mcasures are attractive altern a tives to insecticides, and both can be enhanced by genetic engineering. A wide range of transgenie a pproaches to combatting insect pests are now under development (Estruch et al, 1997). These inelude the transgenic use of insecticida! proteins such as Bacillus thuringiensis toxi ns, polyphcnol oxidases, proteinase inhibitors, chitinases, lectins, vcgetative insecticida! proteins (VIPs), and alpha-amyJase inhibitors.
Nematodes, especialIy root knot n ematodes (Meloidogyne spp.), cause annual losses of US$l 00 billion to \Vorld agriculture. In devclopin g countries, root knot nematodes account for losses of 11%-25%, with peaks of 70% (Bridge et al, 1990). Current chemical control using nematicides (e.g., Aldi carb) is conside red environmenta lIy hazardou s, as well as costly. e rop rotatioos ean be used to limit nem atode infestation, but a re ineffectlve on th eir own. In a few crops, nematode- resistant varieties have bec n developed throu gh conventiooal breeding, but many crops lack sources of nematode resistance (Roberts, 1992). Severa l transge nic approac hes to the development of nem a tode -resistant crops are now emerging. These eomplement the use of transgenes from the erop genepool with those from oth er sources (Atkinso n et al, 1995).
Most erop genepool s lack sources of durable resistance to serious viru ses. Potato leaf roIl, cassava mosaic, and rice tun gro viruses are examples. A ra nge of pathogen -derived rcsi stance (PO R) strategics eme rged in the 1980s (Kavanagh ancl SpilIane, 1995), u sing tra n sgenes derived from the pathogen itself lO trigger resistance against it. The mechanisms underlying different PDR stra tegies, s uch
Relevant Products from Biotechnotogy Research
as coat protein genes, movement proteins, RdRp, antisense, gene silencing, co-suppression, VIGs, 015, and sateUite RNAs, are highly diverse, as also are their e!Teels (Dempsey el al, 1998; Bauleombe, 1999; Beachy, 1999). As a resul! they have beeo used lO generate a far wider range of transgenic options for controlling viral diseases than was available a deeade ago (e.g., Pang el al, 1997).
Tolerance to Abiotic Stresses
Arable land, which comprises about 3% of the earth's surface, is deteriorating and decreasing as a result of soil erosion, salinization, over-cultivation, and acidification. As demand for food grows, many of tbese abiotic stresses are increasing in efTect and magnitude. It is estimated tbat these factors, combined with rising population, will reduce the global per capita availability of arable land from the current level ofO.28 lo 0.17 heetare by the year 20 17 (Dyson, 1996).
Unlike biotic stresses, abiotic stresses do not evolve. Hence, qualitative or single genes may prove effective solutions. A considerable arnount of biotechnology research is now devoted to the development of transgenes to improve crop tolerance to abiotic stresses such as drought, salt, and aluminium. As many resource-poor farmers use marginalland where these stresses are high, the incorporation of these transgenes into their crops may provide significant benefits (HerreraEstrella, 1999). Besides proleetion againsl the stress ilself, the benefils might extend to earlier sowing, longer growing seasons or minimizing soil erosiono None of the prototype technologies developed so far have yet been subject to large-scale field testing for their durability and sustainability under actual farming conditions. Much therefore remains to be done before tbe benefits of this research are reaJized on farmers' fields.
Yield is at once the most widely desired and the most complex of all crop traits. Private companies are investing in the identification of QTLs that will enable thero to breed for yield advances using MAS. The work of companies such as Pioneer Hi Bred and Novartis shows that it is now possible to manipulate severaJ QTLs simultaneously, allowing performance to be fLne-tuned in closely defined environments (M. Gaje, W. Beversdorf, pers. comms.). Combinations of specific quality or resistance traits with high yield, elusive in the past, are expected to become possible. Molecular and tissue culture technologies will ruso make it feasible to handle larger populations for selection, permitting increases in selection intensity and thus in genetic gain roc quantitative traits, including yield.
Biolechnology-Ass isted PPB: Complement or Contradiction?
These new opúons could be extremeIy importan t to resou rce- poor farmers, who often require high yields with specific environmenta l adaptation and quaJity trai ts. The initial development of markers for a set of genetic materials and environments requires from 2 to 4 years, with results that may or may not transfer across sites. Adding this time-frame to PPB will require a dedicated and understanding funding agency and great care llot to rai se fartners' expectations too high.
However, the ultimate benefits to resource-poor farmers from research to increase yields m ay be among the highest obtainable from agricultural r csearch (Lipton, 1999) (see Employrnent and Enterprise Development, p. 95).
Reducin g post-harve st crop losses among resource-poor fanners h as remain ed a major challenge despite progress through conventional breeding. Significant proportions of the harvest are 10st in developing countries as a result of crop physiological processes such as rapid ripening, senescence of the produ ce, or defeetive wound heaJing (as in rapid cassava spoilageJ, in addition to damage by s torage pests.