EARLY RESPONSIVE TO DEHYDRATION 15, a Negative Regulator of Abscisic Acid Responses in Arabidopsis

Abstract

EARLY RESPONSIVE TO DEHYDRATION 15 (ERD15) is rapidly induced in response to various abiotic and biotic stress stimuli in Arabidopsis (Arabidopsis thaliana). Modulation of ERD15 levels by overexpression or RNAi silencing altered the responsiveness of the transgenic plants to the phytohormone abscisic acid (ABA). Overexpression of ERD15 reduced the ABA sensitivity of Arabidopsis manifested in decreased drought tolerance and in impaired ability of the plants to increase their freezing tolerance in response to this hormone. In contrast, RNAi silencing of ERD15 resulted in plants that were hypersensitive to ABA and showed improved tolerance to both drought and freezing, as well as impaired seed germination in the presence of ABA. The modulation of ERD15 levels not only affected abiotic stress tolerance but also disease resistance: ERD15 overexpression plants showed improved resistance to the bacterial necrotroph Erwinia carotovora subsp. carotovora accompanied with enhanced induction of marker genes for systemic acquired resistance. We propose that ERD15 is a novel mediator of stress-related ABA signaling in Arabidopsis.

The multifaceted role of ABA in disease resistance

“…stimulates resistance against the bacterium Erwinia carotovora but suppresses ABA-dependent tolerance to osmotic stress [17]. Although the exact nature of ERD15-dependent resistance is unknown, it seems evident that ERD15 has a role in crosstalk between biotic and abiotic stress resistance.…”

“…Furthermore, the early-acting transcription factor AIM1 (ABSCISIC ACID-INDUCED MYB1) has recently been shown to control positively abiotic stress tolerance and early post-invasive defense in tomato [22]. Other early-acting signaling components, such as the transcription factors ATAF1 (Arabidopsis NAC domain containing protein 1) [24] and the proline oxidase ERD15 (EARLY RESPONSIVE TO DEHYDRATION 15) [17] stimulate post-invasive defense but suppress ABA-dependent abiotic stress tolerance, thereby acting as a branching point in the crosstalk between biotic and abiotic stress. The role of ABA in late defense (Phase III) is mostly negative.…”

EARLY RESPONSIVE to DEHYDRATION 15, a new transcription factor that integrates stress signaling pathways

“…11 These contrasting results in transgene overexpression studies suggest that the Arabidopsis and tomato ERD15 homologs may be functionally diverse.…”

“…11 The overexpression of ERD15 reduced the sensitivity to ABA, as the transgenic plants were less tolerant to drought and were impaired in increasing their freezing tolerance in response to ABA. In contrast, the loss of the ERD15 function caused a hypersensitivity to ABA, and the silenced plants displayed enhanced tolerance to both drought and freezing.…”

Construction of a cDNA library of the Chinese wild Vitis amurensis under cold stress and analysis of potential hardiness-related expressed sequence tags

“…The expression of the ERD6 gene was induced not only by dehydration but also by cold treatment (Kiyosue et al, 1998). The excessive expression of ERD15 would weaken plants' sensitivity to ABA, thus weakening plants' cold resistance and drought tolerance (Kariola et al, 2006). ERD genes are still not fully understood in other plants, especially with regard to grapevine hardiness.…”