Project

What root traits confer resistance against the parasitic weed Striga in cowpea?

Striga gesnerioides is a root parasitic weed in cowpea causing significant yield losses. A number of cowpea genotypes have recently been identified that exhibit partial resistance against this Striga species. The mechanistic explanation for this resistance is still lacking. The project will characterize the resistant mechanism(s) underlying the reduced Striga infection levels in these genotypes using state-of-the art root phenotyping and histological research methods.

Project description

Cowpea (Vigna unguiculata) plants of a range of genotypes differing in S. gesnerioides resistance will be grown in rhizotrons allowing visualization and imaging of the root architecture. Microtome sectioning at the point of parasite infection will allow root anatomical investigations. These will reveal at what level the vascular connection with the host plant might be prevented e.g. suberization/lignification in the endo- or exodermis or Aerenchyma formation in
the cortex. Genotypic specific identification of different mechanisms could inform breeders developing cowpea varieties with multiple and more effective resistance.

Objectives and methods

The objectives of this project are to:

establish cowpea-striga plant system in rhizotrons
study root architectural differences between cowpea genotypes
conduct anatomical studies to determine different striga resistance mechanisms in cowpea

Cowpea plants of a range of Striga-resistant and susceptible genotypes will be grown in the NPEC rhizotron system in Striga-inoculated soil. The rhizotron will enable visualization (and imaging) of root architectural differences between cowpea genotypes. Roots of Striga-infected and Striga-free cowpea plants will be harvested for detailed study. Sections of the cowpea roots at the point of Striga infection/attachment will be made using a cryostat microtome. Following staining and fluorescent microscopic imaging the tissues will be studied and characterized for anatomical features such as root barriers (suberin, lignin) or aerenchyma formation.

Expectations

Some experience with/understanding of experimental plant research, knowledge of plant – soil interactions and statistical knowledge and analytical skills would be expected.

Willingness to work (sometimes long hours) in the lab.

Required skills

Basic plant science knowledge
Basic (statistical) analytical skills
Interest in root and microscopy studies

Types of research / work

A student project on this topic could involve all or components of the following research approaches: (1) a literature study on Striga resistance mechanisms and root research methods, (2) plant growth (and nurturing) in a rhizotron, (3) sectioning of cowpea roots using a microtome, (4) staining, imaging and analyses of microscopic images.