Abstract
In grafted plants, rootstocks assure the mineral nutrition of the scion and modify its development. In this study, we show that two grapevine rootstock genotypes have different shoot branching architectures when cultivated as cuttings and that this trait is transmitted to the scion when grafted. Shoot branching plasticity in response to nitrogen supply was also studied. As strigolactones are known to have a role in the regulation of shoot development in response to nutrient availability, their involvement in the control of scion architecture by the rootstock was investigated. Functional characterization of putative grapevine strigolactone biosynthetic genes in Arabidopsis mutants or grapevine cell suspensions showed similar functions to those of Arabidopsis. Both rootstocks produced strigolactone-like compounds; the quantity produced in response to nitrogen treatments differed between the two rootstock genotypes and correlated with the expression of putative strigolactone biosynthetic genes. Exudation of strigolactone-like compounds by both rootstocks was closely related to the developmental pattern of the scion in grafted plants. These results suggest that differential regulation of strigolactone biosynthesis in response to nitrogen availability may contribute to the control of scion development conferred by each rootstock genotype.
Highlights
In the context of climate change and the development of sustainable agriculture, understanding how crop growth is controlled is a primary objective for plant research
We show that two grapevine rootstock genotypes have different shoot branching architectures when cultivated as cuttings and that this trait is transmitted to the scion when grafted
These results suggest that differential regulation of strigolactone biosynthesis in response to nitrogen availability may contribute to the control of scion development conferred by each rootstock genotype
Summary
In the context of climate change and the development of sustainable agriculture, understanding how crop growth is controlled is a primary objective for plant research. Among the mechanisms that have evolved to enable plants to adapt to environmental changes, the plasticity of plant architecture allows them to adjust their development to optimize growth. The control of root and shoot branching is an example of such an adaptive strategy. While the basic plan of a plant is established during embryogenesis, its architecture, and the branching pattern, can be adjusted in response to 4100 | Cochetel et al While the roles of auxin and cytokinins have long been described in the literature, more recently a number of functions have been ascribed to strigolactones (SLs), including involvement in the complex hormonal regulation network of shoot branching (Gomez-Roldan et al, 2008; Umehara et al, 2008)
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