MOST – MAGIC tomato

Start date: 1 September 2021
End date: 31 August 2024

Heat tolerance is an essential trait for crops in the tropics. Tomato, like many other crops, is sensitive to heat stress and under elevated temperature shows significantly reduced fruit set and therefore yield. Breeding heat-tolerant tomato lines is key for developing hybrids that are in high demand by farmers. However, heat tolerance is a complicated trait and shows low heritability, making low genetic gain during the breeding programs.

In this project, a tomato MAGIC population will be used to investigate whether the reproductive traits responding to heat stress are regulated by several large-effect quantitative trait loci (QTLs) or many small-effect QTLs. We will genotype the MAGIC population using a genotyping-by-sequencing approach and estimate the genetic components with statistical algorithms. The heritability will be partitioned into the genetic variation contributed by markers and by kinship. Further, we will use a genome-wide association study to identify the QTLs regulating the reproductive traits under heat stress.

What results are expected?

• Large-effect QTLs may be detected for a trait that is largely contributed by genetic variation of markers.
• Validation of the QTLs and further applications for other tomato breeding programs are expected.
• If a trait is controlled by many small-effect QTLs, this project can be a prior experiment to simulate and test the accuracy of genomic selection for the trait.