Project properties
Title Determination of the optimal level of 2n pollen for interploidy crosses in potato
Group Plant Breeding, Laboratory of
Project type thesis
Credits 30-39
Supervisor(s) Corentin Clot and Herman van Eck
Examiner(s) Herman van Eck
Contact info corentin.clot@wur.nl, herman.vaneck@wur.nl

Begin date 2024/08/15
End date 2025/02/15
Description Introduction:
Potato breeding can take place at the diploid and at the tetraploid level. One method to bring diploid germplasm to tetraploid offspring is via unreduced gametes. Unreduced gametes are the product of an altered meiosis which maintain the somatic number of chromosome. Unreduced gametes from diploids can fertilize reduced gametes from tetraploids, resulting in tetraploid offspring. Such 4x × 2x interploidy crosses are not successful if the level of unreduced gametes (2nG) is below a certain threshold. When diploids produce 2nG above a certain threshold, the diploids have no value for 2x × 2x crosses for diploid breeding because, the predominant outcome are inviable triploids.

Research question:
What is the minimal, optimal and maximal level of 2nG production to allow high seed set upon 4x × 2x interploidy crosses or 2x × 2x diploid crosses?

Materials and methods:
The student will work in the crossing greenhouse to test 4x × 2x interploidy crosses and 2x × 2x diploid crosses and record berry set and seed set. The experimental design includes controls to monitor the male and female fertility of the parents. Crosses can be made with plants that are known for a lower or higher level of 2nG production, but variable levels of 2nG can also be achieved by mixing haploid and diploid pollen, collected from highly fertile diploid and tetraploid parents. Microscopy of pollen samples allow accurate quantification of the actual percentage of viable haploid and diploid pollen grains. Although the amount of seed set is already a highly informative outcome, it might be desirable to also grow seedlings from these seeds and to verify the ploidy level and the expectations that triploids are inviable.

Season and timing:
This research project should be planned long before the start of the actual work. It takes 6 -10 weeks from planting experimental material in a crossing greenhouse until the first crosses can be made. Planting takes place in February/March and crosses in April/May. A second crossing season starts with planting in August/September and crosses take place in October/November. The workload is not very high but with occasional peaks. Therefore, this thesis project can be combined part-time with other activities such as re-exams or ACT.

The results can be written as thesis report, but aiming for a scientific publication is encouraged.
Used skills Crossing, Microscopy, Statistical Analysis
Requirements You have passed the following courses: Principles of Plant Breeding (PBR-22803), Experimental Design and Data Analysis (PBR-34803)