📣 New Publication: Understanding and modifying starch metabolism to limit yield losses in field-grown cassava

We are pleased to share a new publication that advances our understanding of starch metabolism in cassava and identifies a promising strategy for reducing yield losses under field conditions.

The study identifies AMY3A, a plastid-localised α-amylase, as a key enzyme involved in starch degradation in cassava storage roots following shoot pruning. By suppressing AMY3A expression, the researchers substantially reduced starch losses while maintaining normal plant growth, post-pruning regrowth and stem propagation. These findings highlight starch degradation as a promising target for future breeding and genome-editing approaches aimed at improving cassava yield stability and strengthening food security.

Research Summary (provided by the authors)

Soundbite

Suppressing amylase gene expression substantially reduces starch losses in cassava storage roots without compromising plant regrowth or propagation. This makes the starch degradation pathway an attractive target for breeding and genome-editing strategies aimed at improving yield retention under field conditions in cassava.

Longer Summary

Cassava is ranked amongst the world’s most important food-security crops, providing both calories and income for hundreds of millions of people, especially those living in sub-Saharan African countries. The large storage roots are a sink for photoassimilates, i.e. sugars, which are used to create large amounts of starch – an insoluble sugar polymer. However, when the plants experience stress, such as shoot pruning or drought, these roots can switch to being a source, mobilizing starch reserves to support shoot regrowth. While this response enhances plant resilience, it comes at the cost of reduced yield and diminished root quality traits. This study therefore sought to identify the molecular mechanisms underlying starch remobilization in cassava and to determine whether these pathways could be optimised to reduce yield losses.

Led by researchers in the group of Professor Samuel Zeeman at ETH Zurich, the study combined carbon allocation measurements with transcriptomic and proteomic analyses to investigate the effects of shoot pruning on storage-root metabolism. The authors found that pruning triggered a dramatic decline in root starch content, with greenhouse-grown plants losing nearly half of their starch reserves from young storage roots within ten days. This response was accompanied by widespread transcriptional reprogramming. For example, genes typically associated with starch biosynthesis, respiration and growth were repressed, while genes potentially involved in starch degradation were induced. Among the most highly upregulated genes was AMY3A, which encodes a plastid-localized α-amylase – an enzyme that can hydrolyse starch.

To verify the role of AMY3A in starch mobilization, the researchers generated transgenic cassava lines in which AMY3A expression was suppressed using RNA interference (RNAi). Field experiments demonstrated that reduced AMY3A expression substantially limited pruning-induced starch degradation. In wild-type and control plants, storage roots lost approximately 25–30% of their starch following pruning, whereas AMY3A-suppressed lines lost less – only 4–17%. Importantly, suppressing AMY3A had no significant impact on shoot or root growth. Furthermore, post-pruning regrowth and the sprouting capacity of stem cuttings (critical for cassava propagation by farmers) was unaffected. These results indicate that cassava can maintain adequate regenerative capacity even when starch mobilisation in the roots is reduced.

The study concludes that AMY3A is a key player in the degradation of storage-root starch in cassava and that suppressing its expression can significantly reduce starch and yield losses following shoot pruning. The authors recommend that future genome-editing approaches targeting AMY3A and other candidate genes identified in this study could support the development of cassava varieties with more resilient yields and contribute to improved food security.

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Publication

Understanding and modifying starch metabolism to limit yield losses in field-grown cassava

📄 Read the full publication: https://doi.org/10.1093/plphys/kiag341

Authors: Laure C David, Gabriel Deslandes-Hérold, Carmen Hostettler,  Sylvain Bischof, Michaela Fischer-Stettler,  Anna V Carluccio,  Barbara Pfister, Gavin M George, Wuyan Wang, Livia Stavolone, Andreas Gisel, Simon E Bull, Melanie R Abt, Samuel C Zeeman

Journal: Plant Physiology, Volume 201, Issue 3, July 2026, kiag341, Published: 04 June 2026