Quantitative proteome profile of water deficit stress responses in eastern cottonwood (Populus deltoides) leaves

Abstract

Drought stress is a recurring feature of world climate and the single most important factor influencing agricultural yield worldwide. Plants display highly variable, species-specific responses to drought and these responses are multifaceted, requiring physiological and morphological changes influenced by genetic and molecular mechanisms. Moreover, the reproducibility of water deficit studies is very cumbersome, which significantly impedes research on drought tolerance, because how a plant responds is highly influenced by the timing, duration, and intensity of the water deficit. Despite progress in the identification of drought-related mechanisms in many plants, the molecular basis of drought resistance remains to be fully understood in trees, particularly in poplar species because their wide geographic distribution results in varying tolerances to drought. Herein, we aimed to better understand this complex phenomenon in eastern cottonwood (Populus deltoides) by performing a detailed contrast of the proteome changes between two different water deficit experiments to identify functional intersections and divergences in proteome responses. We investigated plants subjected to cyclic water deficit and compared these responses to plants subjected to prolonged acute water deficit. In total, we identified 108,012 peptide sequences across both experiments that provided insight into the quantitative state of 22,737 Populus gene models and 8,199 functional protein groups in response to drought. Together, these datasets provide the most comprehensive insight into proteome drought responses in poplar to date and a direct proteome comparison between short period dehydration shock and cyclic, post-drought re-watering. Overall, this investigation provides novel insights into drought avoidance mechanisms that are distinct from progressive drought stress. Additionally, we identified proteins that have been associated as drought-relevant in previous studies. Importantly, we highlight the RD26 transcription factor as a gene regulated at both the transcript and protein level, regardless of species and drought condition, and, thus, represents a key, universal drought marker for Populus species.

The Systems Architecture of Molecular Memory in Poplar after Abiotic Stress

“…The two PP2Cs and the LEA4-5 homologs were also upregulated during PS and after PS recovery in mature leaves ( Figure 8A). LEA4-5 protein levels strongly increase in poplar under drought stress conditions for osmoprotection (Abraham et al, 2018). In Arabidopsis, LEA4-5 transcript and protein levels showed the largest response to ABA and salt stress within the LEA4 group (Olvera-Carrillo et al, 2010).…”

Plant Host-Associated Mechanisms for Microbial Selection

“…Host ROS metabolism genes were shown to be associated with Streptomyces (a genus of Actinobacteria ) in Populus leaves (Garcia et al, 2018), potentially showing a more universal drought association between the host and its phytobiome. ROS metabolism has been shown to be a general change across species, omics levels, and compartments in drought (Fang et al, 2015; Abraham et al, 2018; Garcia et al, 2018; Zandalinas et al, 2018) that has impacts beyond that of Actinobacteria .…”

“…Metabolite production and exudates of the plant, including carbohydrates, amino acids, and other nutrients, are altered in response to drought stress (Bouskill et al, 2016; Tripathi et al, 2016; Abraham et al, 2018; Timm et al, 2018). Under more mild drought conditions, rhizodeposition is increased, while under more severe drought conditions, rhizodeposition is decreased, causing the exudate profile to be related to the severity of the drought experienced (Preece and Peñuelas, 2016).…”

Isolation, Characterization, and Pathogenicity of Two Pseudomonas syringae Pathovars from Populus trichocarpa Seeds

“…Because of a well-studied Populus proteomic and metabolite response to various environmental stressors and individual bacteria [31,32], the development of a Populus-P. syringae model system will be beneficial in understanding the mechanics of woody host response to pathogenic bacteria.…”

“…A majority of unsequenced strains isolated from P. tremuloides induced a hypersensitive response in tobacco (95%, n = 21) and tomato (76%) plants [ 30 ]. Because of a well-studied Populus proteomic and metabolite response to various environmental stressors and individual bacteria [ 31 , 32 ], the development of a Populus—P. syringae model system will be beneficial in understanding the mechanics of woody host response to pathogenic bacteria.…”