Agriculture continues to play a leading role in the socio-economic development of Rwanda, employing over 68% of the population and contributing up to 33% of the national gross domestic product. Because of this, the Government of Rwanda has prioritized this sector, and strategically supported it as the main driver towards achieving the country’s development goals.
Despite this policy support, the yield and production of many crops, for example, has steadily declined over the last couple of years. The reduction in production has been attributed to many factors; key among them are decline in soil fertility, climate change, diseases, pests and limited availability of disease resistant varieties.
Figure 1: A soil-less aeropoinic system for Irish potato minituber (pre-basic seed) production: Plantlets from laboratory growing in an aeroponic facility (left); an extensive root system that will yield lots ofminitubers (center) and minitubers from the extensive root system ready for harvesting (right)
Biotechnology provides powerful tools for improvement of agricultural productivity hence increasing food securityin countries like Rwanda with land limitations.One of the most important tools utilized in biotechnology is tissue culture, which has many advantages, one being the large numbers of disease-free planting materials that can be propagated within a short time and space. Others include round the year production of planting materials,higher survival chance of tissue culture plantlets in the field, uniformity in growth and significant increase in yield and quality, making this propagation method the most amenable to commercial agriculture.
Biotechnology program was introduced at the then national agricultural research institute, ISAR,which later merged with agricultural extension organizations to become Rwanda Agriculture Board (RAB), in 2004. Since then, a lot has been achieved, as shown below, not just in tissue culture but also in another research theme on plant diseases diagnostics and/or characterization. In essence, therefore, theprogram implements projects/activities geared towards utilizing modern technologies to improve agricultural productivity hence increasing food security.
Establishment/upgrading of research infrastructure
Apart from carrying out research for development on the two core themes of tissue culture and plant diseases diagnostics and/or characterization, biotechnology program has set out a wider and cross-cutting goal of establishing/upgrading research infrastructure for agricultural research scientists to conduct cutting-edge research for development. For the past seven years, some tissue culture laboratories that were earlier constructed were upgraded and/or expanded, and a new one for Irish potato was recently introduced at Musanze station. In total, we now have five tissue culture laboratories (three at Rubona station and two at Musanze station). These are linked to a good number of screenhouses and soil-less aeroponicsystems to handle plantlets coming from them. As time went by, after establishing the program, there was a strategic decision to upgrade a plant pathology laboratory, which is situated at Musanze station, to help in monitoring of planting materials from tissue culture laboratories for diseases and, more importantly, carry out research on disease diagnostics/characterization to understand their nature in our farming systems, especially the epidemics. We have actually, quite recently, established a much bigger and more equipped plant pathology laboratory at Rubona station, which we are still upgrading to be a state-of-the art facility to handle complex plant disease cases in the country. As a matter of fact, the facility has already started attracting international training workshops and scientists.
Enhancing agricultural productivity through development/optimization and dissemination of plant tissue culture technologies
Tissue culture is the in vitro culture of plant parts under sterile conditions and controlled environment in order to generate whole plants (plantlets). Plant regeneration is normally through two pathways: somatic embryogenesis and micro-shoot induction. Somatic embryogenesis refers to the direct formation of embryos from cells.
During the past seven years, biotechnology program carried out research to develop and/or optimize tissue culture protocols for in vitro production of disease-free superior varieties of vegetatively propagated crops. We have since finalized such protocols for Irish potato, banana and sweet potato. These are now being used to massively produce (commercial production), and disseminate, disease-free planting materials for these crops. For example, the nucleus stock (mother stock) used to produce the larger part of Irish potato seeds produced in the country comes from tissue culture. This is the same thing with banana, albeit at a lower level than Irish potato. For example, about one million plantlets of Irish potato plantlets have been produced and injected in the downstream supporting mass production systems involving a soil-less aeroponics(Figure 1)and screenhouse minituber (pre-basic seed) production. Since these have a multiplier effect on production of seed, the end result is tens of millions of disease-fre seeds produced and disseminated to farmers.Specifically, aeroponic system is far superior since one plantlet from a laboratory can yield 50 minitubers compared to only 6 produced under the conventional screen house system.
Although banana tissue culture has not produced the same amount of plantlets as Irish potato, it has produced enough nucleus stock to be used in a downstream production system called macro-propagation, which massively produces plantlets for re-distribution to farmers. As a matter of fact, this technology, together with the aeroponic system for Irish potato has been disseminated to farmers and other private investors in the country through training. Improved banana varieties produced by tissue culture (Figure 2), which include FHIA 17, FHIA 25, Imporogoma and Injagi, among others, have played a key role in aiding rehabilitation and improvement of banana plantations across the country.
Apart from these crops that are being massively produced, we are at the advanced stages of finalizing research on tissue culture protocols for other crops like cassava, sweet potato, pineapple and coffee, among others. These should be ready for deployment into commercial production soon.We have also facilitated big investors to take on the business of plant tissue culture in the country, and are still doing so. This is because our demonstrated benefits of using tissue culture technology to produce planting materials have created a high demand for these materials, which cannot be solely met by The Government of Rwanda.
Figure 2: Production of banana using tissue culture: Mass multiplication in a laboratory (left) and vigorous disease-free plantlets in a screen house ready to be planted in field
Facilitating plant diseases management through accurate diagnosis and characterization
Plant diseases have, for the last couple of years, been one of the major causes of crop losses in Rwanda. This has been exacerbated by the recent phenomenon of negative effects of climate change as well as cross-boundary movements of seed. Empirical evidence suggests that understanding of diseases plays a central role in their management. It is actually common sense that you cannot fight an enemy you have no information on. Biotechnology program coordinates research activities aimed at understanding the nature of diseases attacking crops in our farming systems through their characterization using advanced modern scientific tools. After understanding them, the program then crafts diagnostics protocols for routine disease surveillance across the country. Surveillance is especially critical for new disease outbreaks to curtail their further spread to non-affected areas. This has, for example, been the case for the 2 notorious recent viral disease epidemics namely the Cassava Brown Streak Disease (CBSD) and Maize Lethal Necrosis (MLN) (Figure 3).
Figure 3: Plant diseases diagnostics: Detecting Cassava Brown Streak Disease (left) and Maize Lethal Necrosis (center) using molecular biology tools (right)
Disease diagnostics is also employed to ensure quality control in our tissue culture laboratories. This is done through indexing of plantlets leaving laboratories, screen houses and right before they are distributed to farmers; basically the entire seed value chain. This helps to ensure that all the planting materials distributed to farmers are disease free.Thus, the program handles plant diseases on two fronts: indexing planting materials at research stations and diagnosing disease problems from farmers’ fields.