Graupner Nadine, Jensen Manfred, Bock Christina, Marks Sabina, Rahmann Sven, Beisser Daniela, Boenigk Jens
Biodiversity, Faculty of Biology, University of Duisburg-Essen, Universitätsstr. 5, D-45141 Essen, Germany.
Genome Informatics, Institute of Human Genetics, University of Duisburg-Essen, University Hospital Essen, Hufelandstr. 55, D-45147 Essen, Germany.
FEMS Microbiol Ecol. 2018 Apr 1;94(4). doi: 10.1093/femsec/fiy039.
Shifts in the nutritional mode between phototrophy, mixotrophy and heterotrophy are a widespread phenomenon in the evolution of eukaryotic diversity. The transition between nutritional modes is particularly pronounced in chrysophytes and occurred independently several times through parallel evolution. Thus, chrysophytes provide a unique opportunity for studying the molecular basis of nutritional diversification and of the accompanying pathway reduction and degradation of plastid structures. In order to analyze the succession in switching the nutritional mode from mixotrophy to heterotrophy, we compared the transcriptome of the mixotrophic Poterioochromonas malhamensis with the transcriptomes of three obligate heterotrophic species of Ochromonadales. We used the transcriptome of P. malhamensis as a reference for plastid reduction in the heterotrophic taxa. The analyzed heterotrophic taxa were in different stages of plastid reduction. We investigated the reduction of several photosynthesis related pathways e.g. the xanthophyll cycle, the mevalonate pathway, the shikimate pathway and the tryptophan biosynthesis as well as the reduction of plastid structures and postulate a presumable succession of pathway reduction and degradation of accompanying structures.
在光养、兼养和异养之间的营养模式转变是真核生物多样性进化中的一种普遍现象。营养模式之间的转变在金藻中尤为明显，并且通过平行进化独立发生了几次。因此，金藻为研究营养多样化的分子基础以及伴随的质体结构途径减少和降解提供了独特的机会。为了分析从兼养转变为异养的营养模式转换过程，我们将兼养的马尔姆帕氏隐藻的转录组与三种专性异养的赭鞭藻目的转录组进行了比较。我们将马尔姆帕氏隐藻的转录组用作异养类群中质体减少的参考。所分析的异养类群处于质体减少的不同阶段。我们研究了几种与光合作用相关的途径的减少，例如叶黄素循环、甲羟戊酸途径、莽草酸途径和色氨酸生物合成，以及质体结构的减少，并推测了途径减少和伴随结构降解的可能顺序。
