本期封面所示為豌豆（Pisum sativum）的一種分枝能力增強的突變體的葉基中的一個生長中的芽子,。
多年來,，教科書上都說有五種“經(jīng)典”的植物激素：生長素（auxin）、赤霉素（gibberellin）,、乙烯（ethylene）,、細胞分裂素（cytokinin） 和脫落酸（abscisic acid）。在這個清單上還可添上油菜素甾醇類化合物（brassinosteroids）,、一氧化氮（nitric oxide） 和茉莉酸類化合物（jasmonates）等,，它們被稱為植物激素（phytohormones），也叫植物生長調(diào)節(jié)素,。
植物枝條的形成由激素調(diào)控,，生長素和細胞分裂素在其中都發(fā)揮作用,。但幾個物種中分枝能力增強的突變體的存在表明，這其中涉及第三個因子,，即一種從根部釋放出的新的植物激素,，它能防止過度分枝。現(xiàn)在,，兩個小組識別出了一類被稱為strigolactones的化合物（或它們的衍生物之一）為這種新的激素,。Strigolactones是在根系分泌物中發(fā)現(xiàn)的，在分枝突變體中含量減少,；這些化合物的外部施用在突變體中抑制枝條的形成,。（生物谷Bioon.com）
生物谷推薦原始出處：
Nature 455, 189-194 (11 September 2008) | doi:10.1038/nature07271
Strigolactone inhibition of shoot branching
Victoria Gomez-Roldan1, Soraya Fermas2, Philip B. Brewer3, Virginie Puech-Pagès1, Elizabeth A. Dun3, Jean-Paul Pillot2, Fabien Letisse4, Radoslava Matusova5, Saida Danoun1, Jean-Charles Portais4, Harro Bouwmeester5,6, Guillaume Bécard1, Christine A. Beveridge3,7,8, Catherine Rameau2,8 & Soizic F. Rochange1,8
1 Université de Toulouse; UPS; CNRS; Surface Cellulaire et Signalisation chez les Végétaux, 24 chemin de Borde Rouge, F-31326 Castanet-Tolosan, France
2 Station de Génétique et d'Amélioration des Plantes, Institut J. P. Bourgin, UR254 INRA, F-78000 Versailles, France
3 ARC Centre of Excellence for Integrative Legume Research, The University of Queensland, Brisbane 4072, Australia
4 CNRS, UMR5504, INRA, UMR792 Ingénierie des Systèmes Biologiques et des Procédés, INSA de Toulouse, F-31400 Toulouse, France
5 Plant Research International, PO Box 16, 6700 AA Wageningen, the Netherlands
6 Laboratory of Plant Physiology, Wageningen University, Arboretumlaan 4, 6703 BD Wageningen, the Netherlands
7 School of Integrative Biology, The University of Queensland, Brisbane 4072, Australia
8 These authors contributed equally to this work.
A carotenoid-derived hormonal signal that inhibits shoot branching in plants has long escaped identification. Strigolactones are compounds thought to be derived from carotenoids and are known to trigger the germination of parasitic plant seeds and stimulate symbiotic fungi. Here we present evidence that carotenoid cleavage dioxygenase 8 shoot branching mutants of pea are strigolactone deficient and that strigolactone application restores the wild-type branching phenotype to ccd8 mutants. Moreover, we show that other branching mutants previously characterized as lacking a response to the branching inhibition signal also lack strigolactone response, and are not deficient in strigolactones. These responses are conserved in Arabidopsis. In agreement with the expected properties of the hormonal signal, exogenous strigolactone can be transported in shoots and act at low concentrations. We suggest that endogenous strigolactones or related compounds inhibit shoot branching in plants. Furthermore, ccd8 mutants demonstrate the diverse effects of strigolactones in shoot branching, mycorrhizal symbiosis and parasitic weed interaction.
