The Virtual Museum of Bacteria

Bacteria and plants

Written by Dr. T. M. Wassenaar Friday, 06 March 2009

Bacteria live near, on, and in plants just like they do with other higher organisms. Plants can benefit from the presence of bacteria or they can suffer from bacterial diseases. Let's start with a mutually benign relationship: plants that are dependent on bacteria for growth, and in return provide the bacteria with food. That is how alfalfa lives happily together with Rhizobium meliloti. The hosting requires communication, and how bacteria and plants talk together is subject of present-day research. Another field of research is applying biotechnology to produce bacteria that are beneficial to plants, for instance in the combat of diseases.

• Bacteria are at the beginning and end of the food cycle. They produce organic matter from CO2 just like plants do, and serve as food for larger organisms. At the other end of the food chain they compost organic material into CO2. Read this interesting article about ecology in a nutshell. Learn more about bacteria's role in the nitrogen cycle.

Bacteria can use the plants just as a support to grow on. You can't normally see them, but if you would make a blue print of a plant leaf on an agar plate that supports growth, the result is a bacterial print of a leaf. Here is a do-it-yourself-instruction to isolate bacteria from bean plants. Did you know that bacteria help plants to grow?

Indirect damage to plants can occur when bacteria promote the formation of ice crystals on soft fruit, like strawberries. After scientists discovered that secreted bacterial proteins formed the core of such crystals, they disabled the gene encoding this protein. These were among the first genetically modified bacteria used to protect crops. Here's what the WHO writes about genetically modified foods. Read about the possibilities of bio-technology and plants.

Bacteria can also cause diseases in plants. It is one of the subjects of Plant Pathology.

• Have a look at this crown gall, ever seen it in real? These 'tumors' that can typically grow on sunflowers, tomatoes, or roses, are caused by bacteria: Agrobacterium tumefaciens is the culprit. Maybe some day the research of plant diseases will help us understand human diseases.
• Plant pathogens and human pathogens have more in common than one would think. The mechanism by which Yersinia pestis, the cause of Plague, kills the host's cells, is very similar to the mechanism used by plant pathogens: Plant and animal bacteria share cell-killing mechanism. Read more about this in the subject category 'pathogenic bacteria'.
• Even if the bacteria can't have their way, they can pass bacterial genes to higher parasites: cyst nematodes (miniature worms) that are parasitic to plants seem to have incorporated specific bacterial genes to do so.
• A few tips for treating sick houseplants.

Plants are not defenseless against infections, they have an 'immune system' too. Disease-resistant plants can recognize pathogenic bacteria, and our understanding of this process may one day result in healthier crops.
Sometimes we have to help Nature to meet our high demands. Crops should be protected against disease, and as an alternative to herbicides and soil-desinfectants like MethylBromide, bacteria may be used as plant growth-promoters.

Bacteria are efficient intruders of plants, and have evolved specific mechanisms to deliver proteins or even DNA into plants. Scientists make use of this: bacteria as a tool to transform plants. How bacteria use the plant's defence for genetic modification.  Do an illustrated tour on plant transformation.

Last Updated on Tuesday, 08 November 2011