BiosafeTrain

What's with plant ecology?

Don't let the five foot five demure lady cloud your judgment on her thoughts on biosafety and genetically modified organisms in the East African region. Like one with a dual personality, her stand on the subject is presented in a rather passionate manner contrary to her everyday otherwise 'shy' behavior.

At 27, Serah Njeru Mwingi is taking a Master in Science (MSc) degree in Plant Ecology, studying full time. "I'm not on study leave, I had just finished my undergraduate course which was a BSc in Horticulture at Egerton University in Njoro, Kenya when I got this scholarship," she pipes with pride.

Why study plant ecology? I ask "I found it interesting and I wanted to study something related to botany." She says and continues, "my past was in horticulture and since this course is broader than horticulture I may end up doing anything from dealing with the environment, to animals and plants and their interaction with the environment.

Wild and cultivated rice

Serah's project is the interactive effects on growth of wild rice, which is Oryza longistaminata, and cultivated rice (Oryza sativa).

What does she mean by interactive effect? "In the event the two are grown together or separately, are there any effects on either with regard to growth or morphology? This includes the growth pattern of a plant, and in the case of rice you look at things such as height, tillering, the leaf area, and the number of pinnacles, and the reproductive stage of the plant." She says and adds, "What I am looking for in the case of rice is the pinnacle initiation stage, heading, booting and the flowering period of the rice. And finally plant production (the yield and biomass). Moreover, I also check if there is gene flow through pollen, which can be facilitated by change of agricultural practices.

In Kenya, rice is the third most important staple food after maize and wheat, and is more important in the diet of urban populations. About 95% of the rice in Kenya is grown under irrigation in paddy schemes managed by the National Irrigation Board (NIB).

The first weeds

Serah knows that there has been a close association between the appearance of weeds and the domestication of crops. Some weeds have evolved important characteristics associated with their life history strategies through mimicking crop characteristics such as growth form and time of seed ripening. These have no doubt been facilitated by the unconscious and unintended human selection for weed populations along with the repeated sowing and harvest cycles of crops.

Weeds may evolve from colonizer species that are adapted to habitats that are continually being disturbed, from the abandonment of domesticated races or escape of crops from cultivated attributes. They can be derivatives of hybrids between wild and cultivated races of crop species, and from gene introgression between the wild and cultivated races.

Crops and weeds can hybridize

"The potential for a crop to hybridize with a weed is highly dependent on sexual compatibility and relatedness between the parent species, normal embryo or endosperm development. Most crops have been dramatically altered in their general appearance following their long history of domestication, probably due to hybridization," she notes.

Cultivated rice species are interfertile with certain close wild relatives. Oryza sativa is compatible with O. longistaminata. Unintended human assistance has helped the wild relatives of rice expand their ranges to all of the inhabited continents, often becoming serious weeds of both cultivated rice and other crops . The fitness of hybrid progeny from crosses between wild and cultivated rice is generally high but hybrids from certain crosses show reduced fertility .

Serah points out that crop-wild weed hybridization can be of great significance in evolution, because this process may result in crop-wild gene flow that could alter the genetic make-up of both populations. Recently, a great interest in crop-wild hybridization has been generated by the concerns of biosafety for genetically modified crops, because gene flow can be an avenue for transgene escape .

The fate of crop-weed hybrids

"Many studies have found crop-weed hybrids to be nearly as fit as their wild parents, but this is not universal" - continues Serah while my appreciation of the determined energy in this small lady continues to grow. "However, a Danish team reported strong fitness decline among hybrid progeny. But there is no doubt that crop genes might persist in wild populations . Thus, it is essential to identify the possible hybrids in a species in order to predict the fate of such genes and also to understand the evolutionary significance of interspecific hybridization. This also can help to assess the ecological consequences caused by transgene escape through gene flow. Such gene flow may result in more aggressive weeds or 'super weeds'. If gene flow from crop to wild plants is common, we could expect that local weeds should be more similar morphologically and genetically to the local cultivars they grow in, than to other cultivars grown other places.

GMO rice? An unnecessary risk

Her views on GMOs are quite candid. "It's a case where people look at the immediate and not the long term effects which might be adverse," she tersely says. "I think more use of hybrids can increase yields. The wild rice O. longistaminata is drought tolerant and if there is a way you can introduce some of these genes into cultivated rice, this means we can use O. sativa (cultivated rice) without much use of water. O. longistaminata is also resistant to certain diseases like the rice yellow mottle virus, which can cause losses in rice. I am not keen on the introduction of GMOs and if we can get results from the above research we may not need it at all," she firmly states.

Her fears are that we may introduce GM rice and cannot prevent gene flow between the cultivated and wild rice, or wild rice and GM rice. As a result, we may face problems in the future and weedy rice may become resistant to pesticides. "If that happens, we would have lost the traits of the original rice and we'd have created a super weed - and that would be more a problem than a solution!" she scoffs.

She is also firm in her support of hybridisation as a plant improvement technique. "I'd definitely support hybridization as it has at most seven generations of breeding and most hybrids are infertile, so there is no chance of gene flow. And you cannot loose the original traits in the event your research does not work out."

The future

But in the event that GM rice is introduced, what next? "In this case there should be regulations on how and to what extent you can use it." Serah further insists that there should be an independent body whose sole purpose is to manage the risk assessment on GM crops.

Serah is single, and at the moment, she is concentrating on her career. "I want to be involved in risk assessment in biosafety either in crop production or in plants."

Her view on the future of GMOs in Kenya is critical: "If the current situation is not improved, there will be a lot of GMO consumption in Kenya without people's knowledge. And if GMOs are cultivated, chances are high it will affect the Kenyan ecosystems. Legislators need to be very careful on the matter relating to genetically modified organisms. There is also a desperate need for communication awareness about this matter", she concludes.

By Joy Owango, February 2007.