DHA - Genes and Evolution


Not all species of Amaranth accumulate the valuable Omega-3 Fatty Acids. Our investigations suggest that the origin of this ability is located in Peru, while the Central American species of Amaranth are unable to produce the desired DHA. The plant does not synthetise Omega-3 Fatty Acids to help vegan members of the species Homo sapiens in sustaining health without sea fish. These compounds are rather important for the plant itself. We think that this metabolic capacity of Peruvian Amaranth species helps them to survive in the harsh climate of the High Andes. By integrating Omega-3 Fatty Acidsthe plant can keep its sensitive membranes liquid even under conditions of the night frosts. The Amaranth species dwelling in the Central American plains do not need this and therefore lack these genes (or do not use them).

Thus, when we find out, how these genes differ, we get by this also valuable markers for breeding. Which gene variant is present in the progeny of a cross, can then be tested by a simple PCR test (similar to those used to detect the Corona virus). This allows to assess already in the seedling stage, whether the plantlet is a good candidate for further breeding, a strategy termed smart breeding but to be discerned from gene technology (only the natural sexuality of the plant is used for the cross, but cutting-edge molecular methods allow to assess the result and, thus, to accelerate the breeding process, because one does not need to probe blindly in the haystack, but can detect the decisive changes directly).

Unfortunately, Amaranth has remained mostly elusive to molecular biology. As first step, we sequenced the genome of two selected types. The first type is a representative of the species A. caudatus, originates from the Urubamba valley near Cusco and accumulates a high level of the Omega-3 Fatty Acid DHA. The other type serves as contrast control and belongst to the Mexican species A. hybridus not able to form DHA. Using these genomes, we were already able to identify several key genes of the metabolism. The DHA metabolism runs in concert with the activation of the jasmonic-acid pathway (both compete for the precursor α-Linolenic Acid). We know that jasmonic acid (acting as stress hormone, similar to the human adrenalin) is central for the plant response to cold stress. We expect, therefore, significant differences in the DHA-metabolism, depending on the climatic conditions during flowering. This is currently investigated in a joint experiment with the University of Hohenheim. How are these genes activated, when Amaranth grows under different climatic conditions? This is now accessible, since we have deciphered these genes.