Lotus japonicus and Lotus berthelotii

Connor''s been gathering entries for a new series on BPotD, and it starts today. Connor writes:

Research Week has officially begun at UBC. This year''s Research Week is especially special as it marks UBC''s 100th anniversary. Events are taking place from March 4-15 that celebrate the research conducted by all of UBC''s faculties, departments, schools and partner institutions.

From March 4 to March 15, Botany Photo of the Day will feature research from the Department of Botany, the Faculty of Forestry and the Faculty of Land and Food Systems.

Dr. Quentin Cronk, a professor in the Faculty of Land and Food Systems and Director of the UBC Botanical Garden and Centre for Plant Research, shares with us today his research on the evolution of bird pollination:

These two photographs show two species of the legume genus Lotus. The yellow flower is Lotus japonicus, a "model organism" for legume biology. Its genome is being sequenced to aid the study of legume biology, especially nodulation, the process by which legumes partner with nitrogen-fixing bacteria to produce their own fertilizer (a major source of nitrogen in the best agricultural systems). In order to separate the genetic components of nodulation, a number of mutants have been raised. You can see a fanciful animation of how these mutants are created and screened by the "magical mutation machine". Lotus japonicus, as the name implies, comes from Japan, but there are many closely related species throughout temperate Eurasia, including the familiar Lotus corniculatus ("bacon and eggs") which is widely introduced in North America (and can be seen all over the UBC campus).

The red flower is a narrow Canary Island endemic called Lotus berthelotii, sometimes grown in warmer gardens under the name "parrot vine". It makes a low, mounded, trailing bush with grey leaves. It looks so different from Lotus japonicus because it is bird-pollinated (Lotus japonicus, like most Lotus species, is bee pollinated).

The flowers are shown side-by-side to illustrate the different pollination mechanisms (for convenience the larger Lotus berthelotii flowers are shown the same size as the Lotus jaonicus flower). Bees are attracted to the flat upright "standard" petal of the yellow flower and land on the closed wing and keel petals, which they have to open to get at the pollen. In consequence the flowers are held horizontally. In Lotus berthelotii, ground perching birds probe down into the flowers from above and therefore the flowers are held in an upright position. Bird pollinated flowers are often red, both to attract birds and to help bird flowers avoid the attentions of bees. For animals like birds, with good colour vision, red contrasts well with green foliage. However, it is camouflaged from bees, as insect eyes are insensitive to the red end of the spectrum.

Together with graduate student Isidro Ojeda, my laboratory is investigating the evolution of bird pollination in Lotus and the gene expression changes that are linked to the very different flower type. The project fits well with our interest both in the evolution and biology of island plants and also in flower development. We are collaborating with the Jardín botanico canario Viera y Clavijo in Gran Canaria and with Arnoldo Santos Guerra of the Jardín de aclimatacion de La Orotava in Tenerife.

Incidentally, one mystery we have still not solved is how we can persuade Lotus berthelotii to flower reliably in western Canada. Whether under glass or outside it remains stubbornly vegetative. We have tried hormone therapys, light therapys, various temperature regimes, not to mention various fertilizer therapys, and yet we only get the occasional flower here in Vancouver. In the Canary Islands, the plants are covered with flowers in April and May. Posted by: Daniel Mosquin    Source