Abstract
Lipid membranes, as primary places of the perception of environmental stimuli, are a source of various oxygenated polyunsaturated fatty acids—oxylipins—functioning as modulators of many signal transduction pathways, e.g., phytohormonal. Among exogenous factors acting on plant cells, special attention is given to drought, especially in highly sensitive crop species, such as yellow lupine. Here, we used this species to analyze the contribution of lipid-related enzymes and lipid-derived plant hormones in drought-evoked events taking place in a specialized group of cells—the flower abscission zone (AZ)—which is responsible for organ detachment from the plant body. We revealed that water deficits in the soil causes lipid peroxidation in these cells and the upregulation of phospholipase D, lipoxygenase, and, concomitantly, jasmonic acid (JA) strongly accumulates in AZ tissue. Furthermore, we followed key steps in JA conjugation and signaling under stressful conditions by monitoring the level and tissue localization of enzyme providing JA derivatives (JASMONATE RESISTANT1) and the JA receptor (CORONATINE INSENSITIVE1). Collectively, drought-triggered AZ activation during the process of flower abscission is closely associated with the lipid modifications, leading to the formation of JA, its conjugation, and induction of signaling pathways.
Highlights
Jasmonates, among them jasmonic acid (JA), as well as its derivatives, such as methyl jasmonate (MeJA), and jasmonoyl-L-isoleucine (JA-Ile), are a diverse group of galactolipidderived phytohormones ubiquitously distributed in plant cells [1]
We provide evidence that JAs are connected to flower abscission processes evoked by drought, which has a strong impact on organ separation
Oxidative stress evoked by Reactive oxygen species (ROS) may lead to lipid peroxidation, As we have previously shown, ROS accumulate during drought-activated abscission zone (AZ) of which could be measured by analysis of MDA [51]
Summary
Jasmonates, among them jasmonic acid (JA), as well as its derivatives, such as methyl jasmonate (MeJA), and jasmonoyl-L-isoleucine (JA-Ile), are a diverse group of galactolipidderived phytohormones ubiquitously distributed in plant cells [1]. There are several reports indicating their involvement in organ separation processes, e.g., in Arabidopsis thaliana [6,7], Bryophyllum calycinum [8], Citrus sinensis [9], Kalanchoe blossfeldiana [10], Rosa chinensis [11], and Phaseolus vulgaris [12]. The positive effect of JA on organ detachment was observed in A. thaliana [6,7], while MeJA stimulated this process in K. blossfeldiana, and B. calycinum [8,10]. Considering that JAs are a large, heterogeneous group of phytohormones, which differ in their chemical structure, spectrum of activity, and possible interaction with other hormones, studies regarding JAs’ role in abscission-related processes are necessary. It has been recently pointed out that flower abscission in Lupinus luteus, economically important
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