CAROTENOID CLEAVAGE DIOXYGENASE 7 modulates plant growth, reproduction, senescence, and determinate nodulation in the model legume Lotus japonicus

• Published in: Journal of experimental botany 2013-04, Vol.64 (7), p.1967-1981
• Main Authors: Liu, Junwei, Novero, Mara, Charnikhova, Tatsiana, Ferrandino, Alessandra, Schubert, Andrea, Ruyter-Spira, Carolien, Bonfante, Paola, Lovisolo, Claudio, Bouwmeester, Harro J, Cardinale, Francesca
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; Arabidopsis; Biological and medical sciences; biomass; Branching; Carotenoids; Carotenoids - metabolism; Economic plant physiology; Flowers; Fundamental and applied biological sciences. Psychology; Gene expression regulation; genetically modified organisms; hormones; internodes; legumes; Lotus; Lotus - enzymology; Lotus - metabolism; Lotus - microbiology; Lotus corniculatus var. japonicus; Lotus japonicus; Mycorrhizae - physiology; mycorrhizal fungi; nodulation; Nodules; parasitic plants; Parasitism and symbiosis; Peas; phenotype; plant development; Plant physiology and development; Plant Proteins - genetics; Plant Proteins - metabolism; plant reproduction; Plant roots; Plant Roots - enzymology; Plant Roots - metabolism; Plant Roots - microbiology; Plants; Plants, Genetically Modified - enzymology; Plants, Genetically Modified - metabolism; Plants, Genetically Modified - microbiology; RESEARCH PAPER; root shoot ratio; roots; senescence; Senescence and abscission; shoots; Symbiosis; Symbiosis (nodules, symbiotic nitrogen fixation, mycorrhiza...); Symbiosis - physiology; Transgenic plants; Vegetative apparatus, growth and morphogenesis. Senescence
• ISSN: 0022-0957; 1460-2431
• DOI: 10.1093/jxb/ert056

Strigolactones (SLs) are newly identified hormones that regulate multiple aspects of plant development, infection by parasitic weeds, and mutualistic symbiosis in the roots. In this study, the role of SLs was studied for the first time in the model plant Lotus japonicus using transgenic lines silenced for CAROTENOID CLEAVAGE DIOXYGENASE 7 (LjCCD7), the orthologue of Arabidopsis More Axillary Growth 3. Transgenic LjCCD7-silenced plants displayed reduced height due to shorter internodes, and more branched shoots and roots than the controls, and an increase in total plant biomass, while their root:shoot ratio remained unchanged. Moreover, these lines had longer primary roots, delayed senescence, and reduced flower/pod numbers from the third round of flower and pod setting onwards. Only a mild reduction in determinate nodule numbers and hardly any impact on the colonization by arbuscular mycorrhizal fungi were observed. The results show that the impairment of CCD7 activity in L. japonicus leads to a phenotype linked to SL functions, but with specific features possibly due to the peculiar developmental pattern of this plant species. It is believed that the data also link determinate nodulation, plant reproduction, and senescence to CCD7 function for the first time.