| New Plant Hormone Discovered |
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An international team of researchers from Australia, France and the Netherlands have discovered a new group of plant hormones called strigolactones. The group, working at the plant physiology lab at Wageningen University, have proven that these compounds are crucial for the regulation of branching in plants. The findings are to be published in 'Nature Magazine' in the near future. This discovery will likely lead to innovations in horticulture production especially in the development of cultivars with more or less branching, a key factor in the aesthetic appearance and flowering of many ornamentals. The researchers studied a group of Pea (Pisium sativa) plants that exhibited uncontrolled branching. These plants did not produce their own strigolactones, but when the hormone was applied to the plants, a conventional branching habit resumed. The growth and development of plants is controlled by hormones that the plants produce themselves. Hormones such as auxins, gibberellins and cytokinins were discovered many years ago and are known to control growth and development of roots and stems. Because plants cannot move around, they use chemical compounds to influence their immediate environment. This new group of hormones, strigolactones, not only influence branching but are important for the interaction between plants and their symbiotic fungi. It has been shown that a mutually beneficial relationship exists between most plants and certain fungi whereby the plants gain increased access to water and soil borne minerals and the fungi benefit by accessing excess plant nutrients. Strigolactones can also be used by disease organisms, such as parasitic plants, by allowing the seedlings to attach themselves to the roots of the host plant and siphoning off nutrients without providing any benefit in return. The host plant is frequently killed by these parasites. The nursery weed Bittercress (Arabidopsis thalina) was the subject for this study, the mutant plants (low strigolactone levels) were found to have fewer parasitic plants germinating on them and exhibited a poor relationship with symbiotic fungi. This could have some interesting applications for biological weed control. The research team has also shown that there is a specific receptor reaction. Not only must the plant produce the hormone, it must have specific physical locations to receive the hormone. This is a very common phenomenon for the action of plant hormones. If a plant does not have the correct receptor binding sites then externally applied strigolactones can not stop the uncontrolled branching. In addition the researchers showed that strigolactones work in very low concentrations and that plants are capable of transporting the compounds internally. Both findings are consistent with current knowledge of plant hormones. This important discovery of this new group of plant hormones is reinforced by the fact that 'Nature Magazine' will also publish, in the same issue, an article by a Japanese research group presenting similar results. This new knowledge will likely be used in horticulture to develop branching regulators and in the breeding of new plants with a diversity of branching habits. It is expected that cut flowers, potted plants and other ornamentals will be treated to influence their visual appearance. The control of branching also has advantages for edible horticulture in crops such as tomato and pepper. Source: De Boomkwekerij |
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