Arabidopsis PCaP2 Functions as a Linker Between ABA and SA Signals in Plant Water Deficit Tolerance

Abstract

Water stress has a major influence on plant growth, development, and productivity. However, the cross-talk networks involved in drought tolerance are not well understood. Arabidopsis PCaP2 is a plasma membrane-associated Ca2+-binding protein. In this study, we employ qRT-PCR and β-glucuronidase (GUS) histochemical staining to demonstrate that PCaP2 expression was strongly induced in roots, cotyledons, true leaves, lateral roots, and whole plants under water deficit conditions. Compared with the wild type (WT) plants, PCaP2-overexpressing (PCaP2-OE) plants displayed enhanced water deficit tolerance in terms of seed germination, seedling growth, and plant survival status. On the contrary, PCaP2 mutation and reduction via PCaP2-RNAi rendered plants more sensitive to water deficit. Furthermore, PCaP2-RNAi and pcap2 seedlings showed shorter root hairs and lower relative water content compared to WT under normal conditions and these phenotypes were exacerbated under water deficit. Additionally, the expression of PCaP2 was strongly induced by exogenous abscisic acid (ABA) and salicylic acid (SA) treatments. PCaP2-OE plants showed insensitive to exogenous ABA and SA treatments, in contrast to the susceptible phenotypes of pcap2 and PCaP2-RNAi. It is well-known that SNF1-related kinase 2s (SnRK2s) and pathogenesis-related (PRs) are major factors that influence plant drought tolerance by ABA- and SA-mediated pathways, respectively. Interestingly, PCaP2 positively regulated the expression of drought-inducible genes (RD29A, KIN1, and KIN2), ABA-mediated drought responsive genes (SnRK2.2, -2.3, -2.6, ABF1, -2, -3, -4), and SA-mediated drought responsive genes (PR1, -2, -5) under water deficit, ABA, or SA treatments. Taken together, our results showed that PCaP2 plays an important and positive role in Arabidopsis water deficit tolerance by involving in response to both ABA and SA signals and regulating root hair growth. This study provides novel insights into the underlying cross-talk mechanisms of plants in response to water deficit stress.

Pseudomonas putida Represses JA- and SA-Mediated Defense Pathways in Rice and Promotes an Alternative Defense Mechanism Possibly through ABA Signaling

“…Interestingly, it was observed that the metabolic effects produced by P. putida are enhancing the overexpression of several PRs. This result is consistent with the accumulation of ABA, which is known to induce the selective up-regulation of some PRs under stress conditions [45,46]. The resistance of rice plants to X. oryzae pv.…”

The bZIP Transcription Factor GmbZIP15 Negatively Regulates Salt- and Drought-Stress Responses in Soybean

“…We conducted a further qRT-PCR analysis and found that the expression of GmWRKY12 was induced by salt and drought treatment in WT and OE plants ( Figure S6A,B ). Moreover, we cloned an ABA-responsive gene ( GmABF1 ) based on RNA-seq data, and its homologue in Arabidopsis ( AtABF1 , AT1G49720) is an ABA-dependent TF that regulates the expression of downstream ABA-inducible genes to improve plant drought resistance [ 10 , 37 ]. Our result demonstrated that its expression is induced by salt and drought stress ( Figure S6A,B ).…”

“…For example, the novel soybean regulatory gene GmTIP2;3 could effectively improve the tolerance of yeast to drought stress [ 43 , 45 ]. In addition, when under abiotic-stress conditions, plant endogenous ABA accumulates rapidly and activates the expression of stress-responsive genes, causing many physiological responses [ 37 , 46 ]. It has been demonstrated that ABA plays key roles in maintaining seed dormancy, inhibiting germination, and preventing seedling growth [ 47 ], and that abiotic stress is able to induce ABA biosynthesis and trigger ABA-dependent signaling pathways [ 48 ].…”

Histone Demethylases Coordinate the Antagonistic Interaction Between Abscisic Acid and Brassinosteroid Signaling in Arabidopsis

“…Bulbs are located in the epidermis of the root and may act as membrane reservoirs for cell expansion ( Uemura et al, 2002 ). PCAP2 is a plasma membrane-associated Ca 2+ -binding protein ( Zhu et al, 2013 ), which acts in ABA response and in the crosstalk between ABA and salicylic acid (SA) during root growth ( Wang et al, 2018b , c ). We hypothesize that JMJ and BZR1 co-regulate PCAP2 expression to control the crosstalk between ABA and BR signals.…”