{"id":757,"date":"2022-05-09T11:06:36","date_gmt":"2022-05-09T09:06:36","guid":{"rendered":"https:\/\/biochemie-nat.cms.rrze.uni-erlangen.de\/?page_id=757"},"modified":"2024-04-15T13:14:50","modified_gmt":"2024-04-15T11:14:50","slug":"ag-wolfgang-zierer","status":"publish","type":"page","link":"https:\/\/www.biochemie.nat.fau.de\/en\/ag-wolfgang-zierer\/","title":{"rendered":"“Cassava Source-Sink\u201c – Group Wolfgang Zierer"},"content":{"rendered":"
\"Fig.
Fig. 1: Storage roots of a 10-month-old cassava plant<\/figcaption><\/figure>\n

We strive to improve cassava storage root yield. Cassava is a tropical crop that is consumed by over 800 million people worldwide and is of special importance for the food security of smallholder farmers in Sub-Saharan Africa.<\/p>\n

The plant grows up to 3-4 meters in height and generates several starchy storage roots under good conditions. These storage roots (Fig. 1<\/strong>) and their starch are the basis for a multitude of foods.<\/p>\n

\"Fig.<\/a>
Fig. 2: A 4-meter tall cassava plant of genotype 60444.<\/figcaption><\/figure>\n

Alongside many other options, the storage roots can be consumed as vegetables in cooked or fried state or their starch can be processed into a variety of products, like the African Gari, a popular kind of puree.<\/p>\n

\"Fig.<\/a>
Fig. 3: Identification of yield-related genes in leaves, phloem, and storage roots with subsequent combination.<\/figcaption><\/figure>\n

IUnfortunately, cassava yield is still comparably low in contrast to the heavily yield-optimized crops like wheat or maize. A sustainable cassava yield improvement would therefore have a large impact on the food security of millions of people. Therefore, we dedicate our work towards cassava yield improvement.<\/p>\n

This goal is unfortunately not within easy reach and a biotechnological improvement of cassava yield is dependent on a very detailed understanding of the plant. Therefore, our work also contains a lot of basic science to unravel the physiological and biochemical processes of this exiting plant species.<\/p>\n

\"Fig.<\/a>
Fig. 4: Different stages of cassava transformation.<\/figcaption><\/figure>\n

We mainly research the regulation of carbohydrate metabolism in auto- and heterotrophic tissues, assimilate transport, as well as developmental processes. Within these processes, we are trying to identify genes with positive impact on storage root yield and to combine them eventually for even larger impact (Fig. 3<\/strong>).<\/p>\n

\"Fig.<\/a>
Fig. 5: Cassava plants in the greenhouse.<\/figcaption><\/figure>\n

We test our target genes via transgenic cassava plants, which we generate ourselves or with the help of our collaboration partner at the ETH Zurich. Cassava transformation comprises refined tissue culture protocols, which can regenerate entire plants from dedifferentiated plant cells (Fig. 4<\/strong>).<\/p>\n

As a first step, we test our modified cassava plants with various techniques in the greenhouse. Plants that can outperform their unmodified genetic background are of course of special interest for us (Fig. 5<\/strong>).<\/p>\n

\"Fig.<\/a>
Fig. 6: Gas-exchange measurements with two measuring devices on a cassava plant.<\/figcaption><\/figure>\n

In addition to the determination of agronomic parameters and different physiological experiments like gas-exchange measurements (Fig. 6<\/strong>), we routinely employ most modern techniques of molecular plant research, like transcriptome- and proteome studies (Fig. 7<\/strong>).<\/p>\n

\"Fig.<\/a>
Fig. 7: Example of a weighted gene correlation network analysis with seven different cassava tissues.<\/figcaption><\/figure>\n

Several metabolite measurements are part of our routine application as well. Enzymatic or chromatographic sugar measurements for instance, grant us insight into primary plant metabolism (Fig. 8<\/strong>).<\/p>\n

\"Fig.<\/a>
Fig. 8: Enzymatic determination of glucose, fructose, and sucrose (A) and chromatographic determination of phosphorylated intermediates (B).<\/figcaption><\/figure>\n

 <\/p>\n

 <\/p>\n

\"Fig.<\/a>
Fig. 9: Characterization of a cassava promoter in a stably transformed promoter-reporter plant.<\/figcaption><\/figure>\n

In addition to the identification and analysis of various genes, we also work on the improvement of tools for the generation of better transgenic cassava plant. Examples are better transformation protocols or the identification of tissue specific promoter sequences (Fig. 9<\/strong>)<\/p>\n

\"Fig.<\/a>
Fig. 10: Cassava storage root cross-section containing fluorescent substances.<\/figcaption><\/figure>\n

Furthermore, we conduct different studies on cassava wild type plants and various breeding material to understand underlying physiological processes, like the storage root formation or the assimilate transport.<\/p>\n

 <\/p>\n

Recently, we could clarify the symplasmic connections in cassava stems and storage roots by introducing and following fluorescent substances into the plant (Fig. 10<\/strong>).<\/p>\n

\"Fig.<\/a>
Fig. 11: Cassava Source-Sink project partners.<\/figcaption><\/figure>\n

Our research group is part of the Cassava Source-Sink (www.cass-research.org<\/a>) project (CASS) and has excess to a large network of plant science techniques and expertise through our various partners (Fig. 11<\/strong>).<\/p>\n

 <\/p>\n

We have close collaborations with:<\/p>\n