Bodyguards for precious seeds—without chemical mace

Naturally occurring, plant-associated bacteria as a crop protection agent are now avail-able for use in crop protection to alleviate the contamination of soil with pesticides—arguably the most environmentally friendly way of plant protection that has been developed to date.

The fungi (Rhizoctonia solani) is stealthy blight, becoming visible only shortly before the harvest infesting beets or corn at their roots. The fungal rot begins early in the season, working its way from the inside out, and only becoming visible in the fall, destroying the possibility of a harvest. Year after year crop failures due to attacks by pests and pathogens are reported in the media despite their being treated with pesticides. Crop failure is further exacerbated by pesticide treatments which cause the death of insects such as bees through neonicotinoids. "There are also more extreme environmental conditions such as periods of hot weather, drought or flood disasters, to be taken into account when considering the ex-tent of damage caused by pesticide use alone", states ACIB researcher Christin Zachow.

The Austrian Centre of Industrial Biotechnology (ACIB) is perfecting protective methods which will make the use of "chemical mace" measures obsolete. One such research project currently underway involves biological plant protection, in which microorganisms (bacteria) work as bodyguards for the safeguarding of seeds like corn, canola, tomato, sorghum, or sugar beet. The underlying principle is that special bacteria are planted in combination with the plant seeds in fields. ACIB engages the growth promoting properties of microorganisms: while the seed germinates, the microorganisms are simultaneously developing and supply-ing the plant with nutrients, promoting growth, warding off pests, reducing the stress on the crop and increasing their resilience.

"Crops are challenged by climate change, drought, and high salted floors. These nutrient deficiencies occur as a result of monoculture practices", states Christin Zachow. Since 2011, Christin Zachow has been managing project research and delivery in collaboration with Prof. Gabriele Berg - a pioneer in this research field - from the Institute for Environmental Bio-technology at Graz University of Technology. Their primary task has been to find bacteria that are adapted to extreme environmental conditions. Every plant needs specific bacteria, and every soil type harbors specific bacteria. For example, researchers who work in the areas of moss and lichen research have found that the former tolerate acidic pH values and nutrient deficiencies, while the latter accept UV-light and drought. Bacteria that promote growth are identified, characterized and tested for their resistance to stress. "We want to know which genes are activated by which particular environmental conditions in order to ensure that the bacteria will be ideally matched with crops under the local conditions", states Zachow. When a promising population of bacteria is found, it is deliberately improved by re-searchers so that the "microbiome" will have an optimal outcome under their given environ-mental conditions. Success has been recorded with the bacterial species Pseudomonas poae and Stenotrophomonas rhizophila. While Stenotrophomonas caused an enormous burst of growth of crops in the salty steppe of Uzbekistan (300 % more than without microbiome treatment), Pseudomonas made a similarly positive impact in the sugar beet test field from ACIB's industry partner KWS SAAT SE in Germany. Five industrial enterprises are currently involved in the research project.

After finalizing the preliminary investigations, target bacteria have come into interaction with their prospective host plants. Zachow: "Plants are searching for exactly those types of bacteria that they need for perfect growth." The bacteria-host-interaction is similar to that which occurs in the human intestine, in which a specific microflora is beneficial to human health. The culmination of the research and development of a commercial product has led to the technique of enclosing a seed in a "bacterial hull". In moist soil types, the bacteria grow along with the germinating seed and at the same time protect it.

Our goal: "We strive to develop plants with optimal health to provide consumers with an optimal basis for a healthy diet", says the scientist, "a functioning biological plant protection system offers a viable alternative to pesticides." Biological plant protection is undeniably a significant step towards ensuring a biologically sound agricultural industry producing healthier food.

Ultimately, the ACIB method is in competition with conventional systems of pesticide driven "plant protection". The chemical industry turns over about 40 billion euros a year in chemical plant protection products worldwide, and a third of these chemicals ends up on the fields in the EU alone. There is a lot of money to be made using biological plant protection when more and more customers call for healthier food.