Scientists discover clues about plant evolution
The genome sequence for sacred lotus has now been reported in the journal Genome Biology. The international team of scientists was led by Ray Ming, a University of Hawaiʻi at Mānoa graduate who is now a professor at the University of Illinois, University of California-Los Angeles Professor Jane Shen-Miller and Director of the Wuhan Botanical Garden at the Chinese Academy of SciencesShaohua Li.
UH Mānoa Researcher Robert Paull and Junior Researcher Nancy Chen of College of Tropical Agriculture and Human Resources’ Department of Tropical Plant and Soil Sciences were involved in this sequencing project. Their role was to analyze and annotate the predicted genes in cell wall metabolism and modification, and to determine their evolutionary relationships. This effort follows from their earlier collaborations on the papaya and Asian pear genomes, both of which efforts led to peer-reviewed articles in Nature and Genome Research.
The sequences revealed that sacred lotus bears the closest resemblance to the ancestor of all eudicots. Eudicots is a term used to refer to one of the two largest groups of angiosperms (flowering plants), constituting more than 70 percent of angiosperm species. Common species include papaya, cabbages, cotton, soybean, grapes and tomato. The other group is the monocots (grasses), which have a single seed leaf and include orchids, grasses, bamboo and banana.
Sacred lotus forms a separate branch of the eudicot family tree because it lacks the characteristic triplication of the genome found in other eudicots. Though it lacks the triplication, sacred lotus did undergo a duplication in its own lineage about 65 million years ago. A high proportion of the duplicated genes have been retained. For instance, the duplicated genes for wax formation (to repel water) and for plant survival in nutrient-poor watery habitats are retained. This gene retention was also seen in the cell wall genes in the analysis by Paull and Chen.
Paull and Chen, in collaboration with a colleague from the Lawrence Berkeley National Laboratory, have already submitted a follow-up paper from the sacred lotus genome paper to another peer-reviewed journal. This paper focuses on the genes involved in cell wall synthesis and modification. It is thought that the cell wall structure plays a crucial role in imparting longevity to the seeds.
Read the College of Tropical Agriculture and Human Resources news release for more on this discovery.