• Question: How come plants can combat diseases? is it just the plants antibodies combatting the disease or infection?

    Asked by henryjones to Clare, Mariana, Pedro, Robert, Susanne on 19 Nov 2012.
    • Photo: Susanne Muekusch

      Susanne Muekusch answered on 19 Nov 2012:

      Tough question.
      Plants do not have antibodies- that’s for animals only. What they can do is to get rid of the part that is infected, by letting their leaves wither and dropping them. Leave gone- disease gone- happy end (doesn’t always work). Plants have that big advantage over animals that are capable of what my plant professor called “complete regeneration”. I keep telling that my plants at home, apparantly they are not aware of that. 🙂

      Plants do also react to infections- but I don’t remember this part.
      But they form a barrier against the outside with fungi and bacteria: they have cell walls and waxen layers to keep things out.

    • Photo: Clare Taylor

      Clare Taylor answered on 19 Nov 2012:

      Susanne is right, no antibodies in plants! But plants do indeed have defenses against infections! Some are pre-formed defenses are already in the plant like the thick plant cell wall and waxy cuticle, which are difficult to penetrate, others are chemicals and enzymes that infectious agents don’t like, but there are also inducible defenses which happen after the infection gets into the plant. These include the cell wall becoming reinforced and the formation of toxic chemicals called reactive oxygen species, like hydrogen peroxide and peroxynitrite – these react with bacterial membranes causing invading bacteria to die. Plants also produce antimicrobial proteins called defensins (we have these too) which also target bacterial membranes. Plant roots can also produce antimicrobial chemicals to try and stop further infections. So the plant doesn’t just stand there and take it, they can fight back!

    • Photo: Mariana Campos

      Mariana Campos answered on 21 Nov 2012:

      Hello Henry,
      This is actually a very good question that scientists still don’t know the answer, although they’ve been studying that for very long.
      It looks like plants can feel when they are being invaded by pathogens. They are very good at producing chemicals. So they produce chemicals that will kill those pathogens. But this as far as I can go. You could think: why are those chemicals not harmful for the plant? Can the plant distinguish different pathogens? I don’t know. Here’s a very nice scientific question.

Comments