NDR1 and the Arabidopsis Plasma Membrane ATPase AHA5 are Required for Processes that Converge on Drought Tolerance and Immunity

Abstract

NON-RACE-SPECIFIC DISEASE RISISTANCE1 (NDR1) is a key component of plant immune signaling, required for defense against the bacterial pathogen Pseudomonas syringae. Plant stress responses have overlapping molecular, physiological, and cell biology signatures, and given the central role of NDR1 during biotic stress perception and signaling, we hypothesized that NDR1 also functions in abiotic stress responses, including in a role that mediates signaling at the plasma membrane (PM) - cell wall (CW) continuum. Here, we demonstrate that NDR1 is required for the induction of drought stress responses in plants, a role that couples stress signaling in an abscisic acid-dependent manner. We show that NDR1 physically associates with the PM-localized H+-ATPases AHA1, AHA2 , and AHA5 and is required for proper regulation of H+-ATPase activity and stomatal guard cell dynamics, providing a mechanistic function of NDR1 during drought responses. In the current study, we demonstrate that NDR1 functions in signaling processes associated with both biotic and abiotic stress response pathways, a function we hypothesize represents NDR1's role in the maintenance of cellular homeostasis during stress. We propose a role for NDR1 as a core transducer of signaling between cell membrane processes and intercellular stress response activation.

Overexpression of NDR1 leads to pathogen resistance at elevated temperatures

“…Previous studies have shown that plant response(s) to both biotic and abiotic stimuli are initiated by rapid, highly specific, changes in the transcriptional landscape; notably, the induction of genes associated with plant defense (Hu et al ., 2012), and the attenuation of those required for growth and reproduction (Lee et al ., 2014; Quint et al ., 2016). These observations have led to the development of models that describe an important role for the co‐regulation of processes that function antagonistically during simultaneous exposure to abiotic and biotic stressors (Hossain et al ., 2018; Kim et al ., 2020; Lu et al ., 2021). To dissect the role of elevated temperature on the activation of ETI, we generated 69 transcriptomes from four plant lines that have reported varied responses related to pathogen infection and hormone signaling, under permissive and elevated temperature (Century et al ., 1997; Tao et al ., 2003; Strawn et al ., 2007; Catinot et al ., 2008; Li et al ., 2021).…”

“…As a broader role for NDR1 in plant processes, recent work has shown that NDR1 and NDR1‐like genes (i.e. HIN; Bao et al ., 2016) play important roles in stress response signaling (Lu et al ., 2021). Among the best characterized examples of NDR1 ‐dependent immune signaling cascades is RESISTANCE TO PSEUDOMONAS SYRINGAE‐2 ( RPS2 ) (Kunkel et al ., 1993), an NB‐LRR‐encoding gene required for the recognition and activation of resistance in response to the Gram‐negative bacterial phytopathogen Pseudomonas syringae expressing the type III effector (T3E) protein AvrRpt2.…”

Overexpression of NDR1 Leads to Pathogen Resistance at Elevated Temperatures

“…Previous studies have shown that plant response(s) to both biotic and abiotic stimuli are typically initiated by rapid, highly specific, changes in the transcriptional landscape; notably, the induction of genes associated with plant defense (Hu et al, 2012), and the attenuation of those required for growth and reproduction (Lee et al, 2014; Quint et al, 2016). Not surprisingly, these observations, as well numerous others, have led to the development of models that describe an important role for the co-regulation of processes that function antagonistically during simultaneous exposure to abiotic and biotic stressors (Hossain et al, 2018; Kim et al, 2020; Lu et al, 2021). In the current study, we sought to further the investigation of a role for rapid transcriptional changes in response to elevated temperature, through the lens of broader immune signaling responses.…”

“…Among these, NON-RACE-SPECIFIC DISEASE RESISTANCE-1 ( NDR1 ) was identified nearly three decades ago as a critical component of plant immune system function (Century et al, 1995), with key functions associated with ETI- and salicylic acid (SA)-dependent, signaling networks in Arabidopsis (Lu, 2009; Lu et al, 2013). As a broader role for NDR1 in plant processes, recent work has shown that NDR1 and NDR1-like genes (i.e., HIN; (Bao et al, 2016) play important roles in stress response signaling (Lu et al, 2021). Among the best characterized examples of NDR1 -dependent immune signaling cascades is RESISTANCE TO PSEUDOMONAS SYRINGE-2 (RPS2) (Kunkel et al, 1993), a NB-LRR-encoding gene required for the recognition and activation of resistance in response to the Gram-negative bacterial phytopathogen P. syringae expressing the type III effector (T3E) protein AvrRpt2.…”