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Xu X, Jibran R, Wang Y, Dong L, Flokova K, Esfandiari A, McLachlan ARG, Heiser A, Sutherland-Smith AJ, Brummell DA, Bouwmeester HJ, Dijkwel PP, Hunter DA. Strigolactones regulate sepal senescence in Arabidopsis. JOURNAL OF EXPERIMENTAL BOTANY 2021; 72:5462-5477. [PMID: 33970249 DOI: 10.1093/jxb/erab199] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2021] [Accepted: 05/08/2021] [Indexed: 05/07/2023]
Abstract
Flower sepals are critical for flower development and vary greatly in life span depending on their function post-pollination. Very little is known about what controls sepal longevity. Using a sepal senescence mutant screen, we identified two Arabidopsis mutants with delayed senescence directly connecting strigolactones with senescence regulation in a novel floral context that hitherto has not been explored. The mutations were in the strigolactone biosynthetic gene MORE AXILLARY GROWTH1 (MAX1) and in the strigolactone receptor gene DWARF14 (AtD14). The mutation in AtD14 changed the catalytic Ser97 to Phe in the enzyme active site, which is the first mutation of its kind in planta. The lesion in MAX1 was in the haem-iron ligand signature of the cytochrome P450 protein, converting the highly conserved Gly469 to Arg, which was shown in a transient expression assay to substantially inhibit the activity of MAX1. The two mutations highlighted the importance of strigolactone activity for driving to completion senescence initiated both developmentally and in response to carbon-limiting stress, as has been found for the more well-known senescence-associated regulators ethylene and abscisic acid. Analysis of transcript abundance in excised inflorescences during an extended night suggested an intricate relationship among sugar starvation, senescence, and strigolactone biosynthesis and signalling.
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Affiliation(s)
- Xi Xu
- Massey University, School of Fundamental Sciences, Palmerston North, New Zealand
- The New Zealand Institute for Plant and Food Research Limited, Palmerston North, New Zealand
| | - Rubina Jibran
- The New Zealand Institute for Plant and Food Research Limited, Palmerston North, New Zealand
| | - Yanting Wang
- Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, The Netherlands
| | - Lemeng Dong
- Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, The Netherlands
| | - Kristyna Flokova
- Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, The Netherlands
| | - Azadeh Esfandiari
- The New Zealand Institute for Plant and Food Research Limited, Palmerston North, New Zealand
| | - Andrew R G McLachlan
- The New Zealand Institute for Plant and Food Research Limited, Palmerston North, New Zealand
| | - Axel Heiser
- Hopkirk Research Institute, AgResearch Limited, Palmerston North, New Zealand
| | | | - David A Brummell
- The New Zealand Institute for Plant and Food Research Limited, Palmerston North, New Zealand
| | - Harro J Bouwmeester
- Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, The Netherlands
| | - Paul P Dijkwel
- Massey University, School of Fundamental Sciences, Palmerston North, New Zealand
| | - Donald A Hunter
- The New Zealand Institute for Plant and Food Research Limited, Palmerston North, New Zealand
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