Can in vitro biology have farm-level impact for small-scale cassava farmers in Latin America?

Abstract

Cassava is uniquely suited for food security and economic development in unfavored areas of the tropics. Development research for cassava is an urgent need. In 1998, the Cassava Biotechnology Network (CBN) convened a workshop of cassava stakeholder groups in Latin America. After hearing an opening statement from representatives of small-scale cassava producers and processors, stakeholders formulated a consensus set of research and development (R&D) priorities. An adequate supply of good-quality planting material of desired varieties was clearly the most urgent, followed by R&D on market-value traits; yield losses due to pests, diseases, and drought; and cropping system flexibility.Two new projects are using in vitro techniques to address priorities of small-scale cassava farmers in Latin America. One project in Colombia combines a nongovernmental organization, a local farmers' association, and the international research center, CIAT, to explore affordable micropropagation. Findings to date show that most culture medium components can be replaced with local products, and a rustic growth room permits good culture growth without electricity or air conditioning. Low-costs system(s) developed will be assessed as a local microenterprise.A second project, in Ecuador, couples local cassava germplasm (with oral histories and an in vitro back-up collection) and elite clones (introduced in vitro) with new concepts in agribusiness development, to restart local farmers' cooperatives after the disastrous 1998-99 el Nifio floods. The project was developed through group planning by the cooperatives, the local technical university, the national agricultural research program, and CIAT.Research to improve in vitro tools focuses on safe and stable conservation and exchange of cassava genetic resources, long-term, less expensive conservation, rapid clonal propagation, and ultimately, genetic transformation technologies to add desired traits to useful cassava varieties.

Disease control and its selection for damaging plant virus strains in vegetatively propagated staple food crops; a theoretical assessment

“…(a) In vitro propagation In vitro propagation programmes for sweet potato (Feng et al 2000) and cassava (Thro et al 1999;Alleman et al 2004) are being developed, but the consequences of the selection that these impose on the virus have not so far been considered. Our results show that although the introduction of in vitro propagated material increases the density of healthy plants (figure 3b), it also selects for virus strains that build up an increased titre in infected plants ( figure 3a).…”

“…Failure to recognize this may lead to considerable economic losses and increased poverty. Specifically, in vitro propagation and diagnostic methods presently receiving a great deal of attention (Thro et al 1999;Feng et al 2000;Monger et al 2001;Alleman et al 2004) have a risk of failure due to the selection of virus strains building up a high within-plant virus titre. Moreover, we have shown that sanitation by roguing is not associated with such a risk, because this disease control method selects for low virus titre strains as well as increasing healthy crop density.…”

Effect of medium composition and explant size on embryogenic calli formation of cassava (Manihot esculenta Crantz) local genotypes

“…Penelitian in vitro ubi kayu difokuskan diantaranya pada propagasi klonal dan teknologi transformasi genetik untuk memperoleh sifat-sifat yang diinginkan (Thro et al, 1999). Jaringan embriogenik telah digunakan sebagai target transformasi genetik maupun regenerasi tanaman ubi kayu transgenik (Taylor et al, 2001).…”

Propagule Quantity and Quality in Traditional Makushi Farming of Cassava (Manihot esculenta): A Case Study for Understanding Domestication and Evolution of Vegetatively Propagated Crops

“…For herbaceous plants, such as yams (Dioscorea spp. ), or relatively short-lived woody plants, such as cassava, the rate of multiplication that can be attained using traditional means of vegetative propagation is notoriously slow compared to seed-propagated crops (e.g., Thro et al 1999), and farmers should often face situations in which the number of high-quality propagules is limiting. Any plant which satisfies other criteria, such as yield, but also produces more clonal propagules, could be strongly favored in reproduction.…”