Investigating molecular determinants for abiotic stress resistance in cassava – a focus on post-harvest physiological deterioration

Cassava is the staple food of nearly one billion people in 105 countries and the fourth most important crop in the developing world. In Indonesia, cassava is consumed as an alternative food to rice and used as animal feed because of its relative cheaper price. Indonesian cassava production is supposed to meet domestic industry and overseas demand. Although large areas are suitable to grow cassava and a higher price is offered in recent years, cassava production in Indonesia can only meet 5% of the demand (according to Indonesian Cassava Society (ICS) records).

Despite its demonstrated potential, several important constraints limit cassava production. One of the major limitations in cassava production is the post-harvest physiological deterioration (PPD), which renders the roots unpalatable and unmarketable within 24-72 hours depending on the genotypes and environmental conditions. PPD is characterised by a blue-black streaking of the vascular tissues. It forces farmers to sell fresh cassava roots or to process them rapidly after harvest as root deterioration is leading to price reduction and, eventually, to its use as feedstock. Losses due to PPD are increasing when the production site is distant from the market site.
The project aims at characterising the natural PPD tolerance in selected cassava accessions available at the Indonesian Institute of Sciences (LIPI) in Cibinong, Indonesia. During the first year of the project, the best performing accessions will be identified using standardised PPD assessment protocols that will be established at LIPI. Selected genotypes with delayed PPD will be tested in collaboration with a local small and medium-sized enterprise as part of LIPI activities on deployment of improved cassava accessions. This approach permits to have an immediate impact for Indonesian cassava growers and industries. In addition, we will use a subset of 20 accessions contrasting for PPD score for enzymatic assays and secondary metabolites measurements. During the second and third year of the project, four contrasting genotypes will be selected for label-free proteomics studies at the ETH Zurich in collaboration with the Functional Genomics Center Zurich. We will perform correlation analysis between proteome modulation and PPD tolerance in order to decipher new markers involved in PPD tolerance.
Field evaluation of cassava accessions allows for generating an immediate output for Indonesian cassava production. Furthermore, the project builds on the use of cutting edge technologies to investigate molecular determinants for PPD tolerance. Development and implementation of molecular techniques will be particularly instrumental in improving cassava in Indonesia.