Aboveground mechanical stimuli affect belowground plant-plant communication

Abstract

Plants can detect the presence of their neighbours and modify their growth behaviour accordingly. But the extent to which this neighbour detection is mediated by abiotic stressors is not well known. In this study we tested the acclimation response of Zea mays L. seedlings through belowground interactions to the presence of their siblings exposed to brief mechano stimuli. Maize seedling simultaneously shared the growth solution of touched plants or they were transferred to the growth solution of previously touched plants. We tested the growth preferences of newly germinated seedlings toward the growth solution of touched (T_solution) or untouched plants (C_solution). The primary root of the newly germinated seedlings grew significantly less towards T_solution than to C_solution. Plants transferred to T_solution allocated more biomass to shoots and less to roots. While plants that simultaneously shared their growth solution with the touched plants produced more biomass. Results show that plant responses to neighbours can be modified by aboveground abiotic stress to those neighbours and suggest that these modifications are mediated by belowground interactions.

Neighborhood Effects of Herbivore-Induced Plant Resistance Vary Along an Elevational Gradient

“…These effects were largely as predicted across elevation and time, and support the idea of plant-plant communication, with both MeJA-treated and untreated neighboring ramets up to 5 m away evidently activating their defense systems, at least in 2016 when the plants were treated. Our results are consistent with other studies showing that above- (Tamogami et al, 2008;Rodriguez-Saona et al, 2009;Moreira et al, 2018b;Kalske et al, 2019) and belowground (Jassbi et al, 2010;Falik et al, 2011;Rasmann et al, 2012;Elhakeem et al, 2018) signals emitted by induced plants can activate the defense system of uninduced neighbors (Dicke and Bruin, 2001;Baldwin et al, 2002;Pickett et al, 2003;Karban et al, 2014;Delory et al, 2016). Moreover, these effects were more pronounced and consistent in the sub-montane and mid-montane climatic zones (Low and Medium sites) than in the subalpine zone (High sites), suggesting that plant-plant communication in bilberry, either through airborne or belowground signaling from MeJA-treated ramets, is apparently modulated by climatic conditions.…”

Airborne signals synchronize the defenses of neighboring plants in response to touch

“…After 24 h of acclimation in the chambers, a maize leaf was carefully touched from the leaf base to the top, using previously described methods (Montgomery et al , 2003; Liu et al , 2007; Anten et al , 2010; Markovic et al , 2016). This treatment with a brush has been used to simulate the mechanical interactions between plants (Elhakeem et al , 2018). Treated plants were touched in the morning for 1 min per day over a period of 6 d. Experiments were limited to 6 d of growth to avoid plants becoming too large and contacting the top of the chambers.…”

Who is my neighbor? Volatile cues in plant interactions

“…Surprisingly, aboveground touch stimuli can also modify belowground plant-plant communication, revealing a new dimension to the functional role of touch induce cues in plant interactions at the community level. 82 This point out on a new level of complexity in belowground plant-plant interactions, showing that the direction and extent of plant root responses to neighbors can be affected by the aboveground touch interaction to which neighbors are exposed. The extraordinary specific response pattern made by the exposed plant could be difficult to explain if we consider the variety, quantity, and quality of competing cues perceived (VOCs, root exudates, brief mechanical contact), taking into account their interactions with the complex mixture of biotic and abiotic factors.…”