Anjanappa, R. B. | bioRxiv Science

bioRxiv2025

A non-rectifying potassium channel increases cassava drought tolerance and storage root yield

Cassava (Manihot esculenta) is an important crop for food security in the tropics, particularly for smallholder farmers in sub-Saharan Africa, where yields are often severely limited by pathogen pressure, nutrient deficiency, and water scarcity. We expressed a non-rectifying Arabidopsis thaliana potassium (K+) channel gene version, AKT2var, in the vascular tissue of cassava plants. The transgenic cassava plants had higher electron transport and CO2 assimilation rates, a higher bulk flow velocity, and increased source-sink carbohydrate transport, as demonstrated by comparative 11C-positron emission tomography and tissue-specific metabolite profiling. Cassava storage root yield was significantly increased in greenhouse experiments and in a multi-year field trial conducted under subtropical conditions. AKT2var plants were also more tolerant to drought stress and had higher storage root yield. Targeted alteration of K+ transport is therefore a promising strategy to improve cassava productivity without additional fertilizer input and in climate-adverse growing conditions.

plant biology↗

bioRxiv2017

Early transcriptome response to brown streak virus infection in susceptible and resistant cassava varieties

Cassava brown streak viruses (CBSVs) are responsible for significant cassava yield losses in eastern sub-Saharan Africa. In the present work, we inoculated CBSV-susceptible and -resistant cassava varieties with a mixed infection of CBSVs using top-cleft grafting. Virus titres in grafted scions were monitored in a time course experiment in both varieties. We performed RNA-seq of the two cassava varieties at the earliest time-point of full infection in the susceptible scions. Genes encoding proteins in RNA silencing and salicylic acid pathways were regulated in the susceptible cassava variety but transcriptional changes were limited in the resistant variety. After infection, genes related to callose deposition at plasmodesmata were regulated and callose deposition was significantly reduced in the susceptible cassava variety. We also show that {beta}-1,3-glucanase enzymatic activity is differentially regulated in the susceptible and resistant varieties. The differences in transcriptional responses to CBSV infection indicate that resistance involves callose deposition at plasmodesmata but does not trigger typical anti-viral defence responses. A meta-analysis of the current RNA-seq dataset and selected, previously reported, host-potyvirus and virus-cassava RNA-seq datasets revealed comparable host responses across pathosystems only at similar time points after infection or infection of a common host.\n\nHIGHLIGHTOur results suggest that resistance to CBSV in cassava involves callose deposition at the plasmodesmata and our meta-analysis of multiple virus-crop RNA-seq studies suggests that conserved responses across different host-virus systems are limited and depend greatly on time after infection.

plant biology↗