Water lilies are known for being aquatic plants that are often used in ponds and man-made rivers for aesthetics and sometimes they end up as invasive species. But, unknown to many, water lilies belong to order Nymphaeles which, along with plant order Amborellales and Austrobaileyales, form the ANA-grade of angiosperms and are living representatives of the group that diverged early on from the current mesangiosperm species.
An international team led by scientists from Pennsylvania State University aims to understand the evolution of angiosperms and to be able to do this they used next-generation sequencing technology on the genome and transcriptome of the water lily. The water lily possesses all characteristics of an angiosperm: the presence of floral organs and quite simply, the production of large, showy flowers for reproduction.
According to Hong Ma, associate dean for research and innovation and professor of plant molecular biology at Pennsylvania State University, the team performed sequencing and analysis of the genome of an Amborella species. The Amborella is among the groups that diverged early on from other angiosperms and lacks big, showy and colorful flowers. The attractive floral scent that is meant to attract pollinators is also absent from this species. "We were interested in the water lily genome to help us understand how these traits evolved." Ma said.
Through comparing water lily genome and genomes of Amborella, other angiosperm species, and some gymnosperms, the scientists confirmed that the Amborella (which possesses a few attributes common to the gymnosperms) is the "most punctual" in the group to isolate themselves from other groups of flowering plants. After the Amborella, the water lilies were the next group to diverge from Austrobaileyales and the rest of the angiosperms.
The methodology the scientists used for this experiment involves molecular dating to be able to appraise the separation of water lilies from other aquatic plants between 147 to 185 million years ago complete with an entire genome duplication and polyploidy event. The scientists were also able to analyze genes in the genome of the water lily that is important for generating molecules for the production of color and fragrance -- this same characteristic that is absent from Amborella.
In this experiment, the scientists were able to identify a large extension in the number of genes associated with the production of the floral fragrance in water lilies. There are two important things that the scientists were able to find in this experiment: 1) they found out that these specific genes evolved parallel to other angiosperms and, 2) identified proteins that play a vital role in producing the attractive colors of the flowers of the water lily.
Ma explained that acquiring the genome from water lilies enabled the team to explore important traits in flower plants -- especially the horticultural variety. Plants with brightly-colored flowers probably evolved by interacting with pollinators. This behavior probably made way to the high success of angiosperms. "Identification of the key synthetic genes of blue petals has important reference value for breeding blue petal varieties." He said. The findings of this study conducted by an international team of scientists are published in Nature.
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