Article

Shade Avoidance Influences Stress Tolerance in Maize

[ "Postdoctoral research associate, postdoctoral research associate, graduate student, Professor, and Professor, Department of Plant Agriculture, Crop Science Building, University of Guelph, 50 Stone Road E., Guelph, ON N1G 2W1, Canada. Current address of first author: Agriculture and Agri-food Canada, Greenhouse and Crops Processing Centre, 2585 County Rd. 20, Harrow, ON N0R 1G0, Canada. Corresponding author's E-mail: "]
Weed Science (Impact Factor: 1.87). 07/2011; 59(July-September 2011):326-334. DOI: 10.1614/WS-D-10-00159.1

ABSTRACT

Previous studies have suggested that the reduction in the root/shoot ratio that accompanies the shade avoidance response may reduce the tolerance of individuals to subsequent nutrient or moisture limitations. In this work, we examined the impact of the shade avoidance response on maize seedling growth and development and the response of these plants to a subsequent abiotic stress. Seedlings were grown in a field fertigation system under two light quality environments, ambient and a low red to far-red ratio, which were designed to simulate weed-free and weedy conditions, respectively. This system also enabled the controlled restriction of water and nutrients, which reduced the relative growth rate of the crop and created a secondary stress. Results of this study indicate that, while the shade avoidance response did reduce the root/shoot ratio in maize, this effect did not reduce plant tolerance to subsequent abiotic stress. Rather, the apparent additivity or synergism of shade avoidance and the secondary stressor on yield loss depended on whether the net effect of these two stressors was sufficiently large to shift the population toward the point where reproductive allometry was broken. Nomenclature: Maize, Zea mays L.

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    • "Ruan hypocotyl elongation, whereas the root growth is stalled. At the meantime, a low ratio of red : far-red light under shade also induces hypocotyl elongation and promotes shoot over root growth (Page et al. 2011). As a result, cotyledons, together with shoot apex, are pushed towards the light. "
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    ABSTRACT: Roots and shoots are distantly located but functionally interdependent. The growth and development of these two organ systems compete for energy and nutrient resource, and yet, they keep a dynamic balance with each other for growth and development. The success of such a relationship depends on efficient root-shoot communication. Aside from the well-known signaling processes mediated by hormones such as auxin and cytokinin, sugars have recently been shown to act as a rapid signal to coordinate root and shoot development in response to endogenous and exogenous clues, in parallel to their function as carbon and energy resources for biomass production. New findings from studies on vascular fluids have provided molecular insights into the role of sugars in long-distance communications between shoot and root. In this review, we discussed phloem- and xylem- translocation of sugars and the impacts of sugar allocation and signaling on balancing root-shoot development. Later in the article, we took the shoot-root carbon-nitrogen allocation as an example to illustrate the communication between the two organs through multi-layer root-shoot-root signaling circuits, comprising sugar, nitrogen, cytokinin, auxin and vascular small peptide signals.
    Full-text · Article · Oct 2015 · Functional Plant Biology
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    • "The pH of the diluted solution was adjusted to 6.5–6.7 by the addition of HCl. Two fertigation tubes calibrated to deliver a minimum of 10 ml of nutrient solution per minute were inserted into each pail (Page et al., 2011). For the positive nitrogen treatment (+N), 1.1 g of urea was dissolved into 1 L H 2 0 (37 mM total N, to compensate for leaching) and was provided to the plants at weekly intervals (13 times total) over the course of the experiment, with control "
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    ABSTRACT: The small grain cereal, finger millet (FM, Eleusine coracana L. Gaertn), is valued by subsistence farmers in India and East Africa as a low-input crop. It is reported by farmers to require no added nitrogen (N), or only residual N, to produce grain. Exact mechanisms underlying the acclimation responses of FM to low N are largely unknown, both above and below ground. In particular, the responses of FM roots and root hairs to N or any other nutrient have not previously been reported. Given its low N requirement, FM also provides a rare opportunity to study long-term responses to N starvation in a cereal species. The objective of this study was to survey the shoot and root morphometric responses of FM, including root hairs, to low N stress. Plants were grown in pails in a semi-hydroponic system on clay containing extremely low background N, supplemented with N or no N. To our surprise, plants grown without deliberately added N grew to maturity, looked relatively normal and produced healthy seed heads. Plants responded to the low N treatment by decreasing shoot, root, and seed head biomass. These declines under low N were associated with decreased shoot tiller number, crown root number, total crown root length and total lateral root length, but with no consistent changes in root hair traits. Changes in tiller and crown root number appeared to coordinate the above and below ground acclimation responses to N. We discuss the remarkable ability of FM to grow to maturity without deliberately added N. The results suggest that FM should be further explored to understand this trait. Our observations are consistent with indigenous knowledge from subsistence farmers in Africa and Asia, where it is reported that this crop can survive extreme environments.
    Full-text · Article · Aug 2015 · Frontiers in Plant Science
  • Source
    • "Ruan hypocotyl elongation, whereas the root growth is stalled. At the meantime, a low ratio of red : far-red light under shade also induces hypocotyl elongation and promotes shoot over root growth (Page et al. 2011). As a result, cotyledons, together with shoot apex, are pushed towards the light. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Roots and shoots are distantly located but functionally interdependent. The growth and development of these two organ systems compete for energy and nutrient resource, and yet, they keep a dynamic balance with each other for growth and development. The success of such a relationship depends on efficient root-shoot communication. Aside from the well-known signalling processes mediated by hormones such as auxin and cytokinin, sugars have recently been shown to act as a rapid signal to co-ordinate root and shoot development in response to endogenous and exogenous clues, in parallel to their function as carbon and energy resources for biomass production. New findings from studies on vascular fluids have provided molecular insights into the role of sugars in long-distance communications between shoot and root. In this review, we discussed phloem- and xylem- translocation of sugars and the impacts of sugar allocation and signalling on balancing root-shoot development. Also, we have taken the shoot-root carbon-nitrogen allocation as an example to illustrate the communication between the two organs through multi-layer root-shoot-root signalling circuits, comprising sugar, nitrogen, cytokinin, auxin and vascular small peptide signals.
    Full-text · Article · Jan 2015 · Functional Plant Biology
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