Choice and No-Choice Assays for Testing the Resistance of A. thaliana to Chewing Insects

Published 5/14/2008
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Biology
 

Summary

Plant resistance to chewing insect herbivores can be tested in several ways. Here, we demonstrate how to set-up a choice and a no-choice experiment with the model plant Arabidopsis thaliana to identify resistance against the pest species Pieris rapae.

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De Vos, M., Jander, G. Choice and No-Choice Assays for Testing the Resistance of A. thaliana to Chewing Insects. J. Vis. Exp. (15), e683, doi:10.3791/683 (2008).

Abstract

Larvae of the small white cabbage butterfly are a pest in agricultural settings. This caterpillar species feeds from plants in the cabbage family, which include many crops such as cabbage, broccoli, Brussel sprouts etc. Rearing of the insects takes place on cabbage plants in the greenhouse. At least two cages are needed for the rearing of Pieris rapae. One for the larvae and the other to contain the adults, the butterflies. In order to investigate the role of plant hormones and toxic plant chemicals in resistance to this insect pest, we demonstrate two experiments. First, determination of the role of jasmonic acid (JA - a plant hormone often indicated in resistance to insects) in resistance to the chewing insect Pieris rapae. Caterpillar growth can be compared on wild-type and mutant plants impaired in production of JA. This experiment is considered "No Choice", because larvae are forced to subsist on a single plant which synthesizes or is deficient in JA. Second, we demonstrate an experiment that investigates the role of glucosinolates, which are used as oviposition (egg-laying) signals. Here, we use WT and mutant Arabidopsis impaired in glucosinolate production in a "Choice" experiment in which female butterflies are allowed to choose to lay their eggs on plants of either genotype. This video demonstrates the experimental setup for both assays as well as representative results.

Protocol

No Choice Experiment:

  1. Carefully enclose the Arabidopsis plant of interest in a plastic cup. In this case: Col-0 (WT) and a mutant impaired in the production of JA. Make sure you limit damage to the leaves. For that I use the back of this paintbrush.
  2. Use a fine paintbrush to take a freshly hatched larvae from the colony on cabbage.
  3. Carefully place the larva on the Arabidopsis plants.
  4. Weight larva at day 4, 7, 10. TIP: Grow your plants under short day conditions (8 hr light) to increase vegetative growth (1 larva can fulfill its full life cycle on 1 plant).

Choice Experiment:

  1. Two plants are selected, one of each genotype. Best is to grow plants in the same pot, to limit other factors, such as tray effects, etc.
  2. Place the plants in a butterfly cage.
  3. Select a fertile female. I usually catch a female that is actively laying eggs in the rearing colony.
  4. Release the female in the cage with the choice of two plants for 24 hrs.

TIP 1: To eliminate an affect of learning, do not reuse females for subsequent choice tests.

TIP 2: One can only compare plants that have a similar growth phenotype. Alternatively, you could mount a leaf from each genotype on top of a Erlenmeyer flask and compare their attractiveness to a female.

Please visit Annual Reviews of Plant Biology for more information about this protocol and plant immunity to insect herbivory.

 

Comments

6 Comments

  1. I thought you did an excellent job, nice and clear explainations, good transitions and summary.

    Reply
    Posted by: Anonymous
    June 14, 2008 - 3:06 PM
  2. 1. perhaps you could explain why you use  arabidopsis instead of cabbage. My assumption is that much work, including sequencing of the genome, had been done on the arabidopsis so you were able to add-remove genetic components you wanted to test for. ². how long is a generation of the cabbage butterfly? 3. Choice experiment. Why did you not use multiple larvae released into cage with the two types of arabidopsis? Some what confusing because there were two different growth stages and two different stimuli tested for in the same testing 4. Excellent job of editing and presenting. It fit nicely on the video   Jay

    Reply
    Posted by: Anonymous
    July 6, 2008 - 8:00 AM
  3. Dear Jay, Thank you for your comments. Let me answer your questions and give you some additional information on the life cycle of Pieris rapae. 1. Larvae of the small white butterfly will feed from almost all cruciferous plants. We use Arabidopsis thaliana because of its short generation time, small size and above all its sequenced genome and vast number of available mutants. These mutants allow us to unravel the defense responses during the host-insect interaction. As demonstrated in the video, we show that jasmonic acid plays a major role in the plant's defensive capacities towards Pieris rapae. Interestingly, we also show that glucosinolates, whose breakdown products are toxic to many generalist caterpillars, are used as by Pieris rapae female butterflies (specialist on cruciferous plants) as oviposition cues. We have recently published a paper in Plant Physiology (March ²008) on this topic. ². Pieris rapae life cycle. The development of Pieris rapae strongly depends on the temperature and ranges from 5-7 weeks. We rear our insects at ²3C. Eggs hatch in 3-7 days; Larvae have 5 larval stages (L1-L5; ~ 10-14 day); Pupae (7-14 days); Adults (~14-²0 days). Under our rearing conditions eggs hatch in 5 days, complete larval development until pupation takes 1² days, pupa take ~7 days to eclosion, adult life is ~² weeks. 3. Using the video we wanted to show different experimental set-ups for testing plant-insect interaction. A choice test (preference) will give you additional insights that are not necessarily displayed in a no-choice test (edibility). There are other possibilities for choice tests, including the one you mentioned. The results obtained with this approach, e.g. leaf area eaten, are hard to quantify and rather subjective. Therefore, we mostly use the no-choice set-up to determine the effect on caterpillar performance. Martin 

    Reply
    Posted by: Anonymous
    July 7, 2008 - 11:05 AM
  4. The demo was very clear to me, but the music was .........
    Maybe you should point out in the video, that these experiments have to repeated.

    Reply
    Posted by: Birgid B. S.
    July 7, 2009 - 2:13 AM
  5. I had a question regarding the increase of weight of the Caterpillar.well the readings are taken on 4,7,10 day.The coi1 plants if are consumed earlier ,how come the weight is increased,if no plant material is left till 10th day?

    Reply
    Posted by: Anonymous
    January 14, 2012 - 11:19 PM
  6. I love this vedio and may you tag this vedio to me

    Reply
    Posted by: Anonymous
    March 16, 2012 - 11:44 PM

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