As sessile organisms, plants are exposed to pathogen invasions and environmental fluctuations. To overcome the challenges of their surroundings, plants acquire the potential to sense endogenous and ...exogenous cues, resulting in their adaptability. Hence, plants have evolved a large collection of plasma membrane‐resident receptors, including RECEPTOR‐LIKE KINASEs (RLKs) and RECEPTOR‐LIKE PROTEINs (RLPs) to perceive those signals and regulate plant growth, development, and immunity. The ability of RLKs and RLPs to recognize distinct ligands relies on diverse categories of extracellular domains evolved. Co‐regulatory receptors are often required to associate with RLKs and RLPs to facilitate cellular signal transduction. RECEPTOR‐LIKE CYTOPLASMIC KINASEs (RLCKs) also associate with the complex, bifurcating the signal to key signaling hubs, such as MITOGEN‐ACTIVATED PROTEIN KINASE (MAPK) cascades, to regulate diverse biological processes. Here, we discuss recent knowledge advances in understanding the roles of RLKs and RLPs in plant growth, development, and immunity, and their connection with co‐regulatory receptors, leading to activation of diverse intracellular signaling pathways.
In nature, plants are continuously exposed to invader organisms and changing environmental conditions that need to be monitored to activate appropriate responses, allowing survival. This review presents the current knowledge of the cell surface receptor‐based surveillance system employed by plants to modulate immune responses, and coordinate growth and development.
The rapid alkalinization factor (RALF) peptide negatively regulates cell expansion, and an antagonistic relationship has been demonstrated between AtRALF1, a root-specific RALF isoform in ...Arabidopsis, and brassinosteroids (BRs). An evaluation of the response of BR signaling mutants to AtRALF1 revealed that BRI1-associated receptor kinase1 (bak1) mutants are insensitive to AtRALF1 root growth inhibition activity. BAK1 was essential for the induction of AtRALF1-responsive genes but showed no effect on the mobilization of Ca2+ and alkalinization responses. Homozygous plants accumulating AtRALF1 and lacking the BAK1 gene did not exhibit the characteristic semi-dwarf phenotype of AtRALF1-overexpressors. Biochemical evidence indicates that AtRALF1 and BAK1 physically interact with a Kd of 4.6 μM and acridinium-labeled AtRALF1 was used to demonstrate that part of the specific binding of AtRALF1 to intact seedlings and to a microsomal fraction derived from the roots of Arabidopsis plants is BAK1-dependent. Moreover, AtRALF1 induces an increase in BAK1 phosphorylation, suggesting that the binding of AtRALF1 to BAK1 is functional. These findings show that BAK1 contains an additional AtRALF1 binding site, indicating that this protein may be part of a AtRALF1-containing complex as a co-receptor, and it is required for the negative regulation of cell expansion.
Cell death is intrinsically linked with immunity. Disruption of an immune-activated MAPK cascade, consisting of MEKK1, MKK1/2, and MPK4, triggers cell death and autoimmunity through the ...nucleotide-binding leucine-rich repeat (NLR) protein SUMM2 and the MAPK kinase kinase MEKK2. In this study, we identify a Catharanthus roseus receptor-like kinase 1-like (CrRLK1L), named LETUM2/MEDOS1 (LET2/MDS1), and the glycosylphosphatidylinositol (GPI)-anchored protein LLG1 as regulators of mekk1-mkk1/2-mpk4 cell death. LET2/MDS1 functions additively with LET1, another CrRLK1L, and acts genetically downstream of MEKK2 in regulating SUMM2 activation. LET2/MDS1 complexes with LET1 and promotes LET1 phosphorylation, revealing an intertwined regulation between different CrRLK1Ls. LLG1 interacts with the ectodomain of LET1/2 and mediates LET1/2 transport to the plasma membrane, corroborating its function as a co-receptor of LET1/2 in the mekk1-mkk1/2-mpk4 cell death pathway. Thus, our data suggest that a trimeric complex consisting of two CrRLK1Ls LET1, LET2/MDS1, and a GPI-anchored protein LLG1 that regulates the activation of NLR SUMM2 for initiating cell death and autoimmunity.
ATP production requires the establishment of an electrochemical proton gradient across the inner mitochondrial membrane. Mitochondrial uncouplers dissipate this proton gradient and disrupt numerous ...cellular processes, including vesicular trafficking, mainly through energy depletion. Here we show that Endosidin9 (ES9), a novel mitochondrial uncoupler, is a potent inhibitor of clathrin-mediated endocytosis (CME) in different systems and that ES9 induces inhibition of CME not because of its effect on cellular ATP, but rather due to its protonophore activity that leads to cytoplasm acidification. We show that the known tyrosine kinase inhibitor tyrphostinA23, which is routinely used to block CME, displays similar properties, thus questioning its use as a specific inhibitor of cargo recognition by the AP-2 adaptor complex via tyrosine motif-based endocytosis signals. Furthermore, we show that cytoplasm acidification dramatically affects the dynamics and recruitment of clathrin and associated adaptors, and leads to reduction of phosphatidylinositol 4,5-biphosphate from the plasma membrane.
This paper studies the influence of community capitals on well-being through a Community Capital Index (CCI) within coffee-growing families in southern Colombia. Our results show different farm ...typologies, with different levels of capital endowment translated into well-being that, in our case, were represented in the CCI. Specifically, social and political capitals positively affect coffee-growing families' decisions in terms of life strategies. The results of this study increase our understanding of welfare enhancement and its relationship with capital endowment according to the type of coffee producer, having implications for the planning of more effective programs towards the improvement of quality of life.
RALF is a small (5 kDa) and ubiquitous plant peptide signal. It was first isolated from tobacco leaf protein extracts owing to its capacity to alkalinize the extracellular media of cell suspensions. ...RALFs inhibit root growth and hypocotyl elongation, and a role for RALFs in cell expansion has also been proposed. Arabidopsis has 37 RALF isoforms (AtRALF), but only a small group of nine has high primary structure identity to the original RALF peptide isolated from tobacco. Herein, we report the heterologous production of these nine peptides in Escherichia coli and the evaluation of their activity in five biological assays. All AtRALF peptides produced showed strong alkalinizing activities, with the exception of the pollen-specific isoform AtRALF4. Although it exhibited no inhibitory activity in the root growth and hypocotyl elongation assays, AtRALF4 is a strong inhibitor of pollen germination. Our data demonstrate that the divergence in the tissue specificity and gene expression patterns of the different AtRALFs does not change the fact that their main role seems to be the regulation of cell expansion. Furthermore, different activities in the alkalinization assays upon the addition of two consecutive and saturating doses of the peptides suggest that the peptides are likely being sensed by specific receptors.
•We heterologously expressed nine recombinant AtRALFs in Escherichia coli.•Only AtRALF4 has no alkalinizing activity but inhibits pollen germination.•AtRALFs 1, 23 and 34 alkalinize cell media but don't inhibit pollen germination.•Activity assays suggest the existence of AtRALF-specific receptors.•Sequence identity among AtRALFs suggest few determinants of biological activity.
The cultivation of cocoa (Theobroma cacao L.) is traditionally managed under shade because of its photosynthetic characteristics; however, its behavior can vary according to the genotype and ...environmental conditions where it is grown. In this sense, here, we explore the possible mechanisms of protection against radiation stress and how these mechanisms are affected by variation between cocoa genotypes. Therefore, we evaluate the effect of the radiation level (HPAR, 2100 ± 46 mol m−2 s−1; MPAR, 1150 ± 42 mol m−2 s−1; LPAR, 636 ± 40 mol m−2 s−1) on the water status and gas exchange in plants of different cocoa genotypes (CCN-51, ICS-1, ICS-95, LUKER-40 and LUKER-50), and the occurrence of photoinhibition of PSII (as a marker of photodamage), followed by a characterization of the protection mechanisms, including the dynamics of photosynthetic pigments and enzymatic and non-enzymatic antioxidant systems. We found significant changes in the specific leaf area (SLA) and the water potential of the leaf (ΨL) due to the level of radiation, affecting the maximum quantum yield of PSII (Fv/Fm), which generated dynamic photoinhibition processes (PIDyn). Cocoa genotypes showed the lowest Light-saturated maximum net carbon assimilation rate (Amax) in HPAR. Moreover, the maximum carboxylation rate (Vcmax) was negatively affected in HPAR for most cocoa genotypes, indicating less RuBisCO activity except for the ICS-95 genotype. The ICS-95 showed the highest values of Vcmax and maximum rate of regeneration of ribulose-1,5-bisphosphate (RuBP) controlled by electron transport (Jmax) under HPAR. Hence, our results show that some genotypes were acclimated to full sun conditions, which translated into greater carbon use efficiency due to the maximization of photosynthetic rates accompanied by energy dissipation mechanisms.
ABSTRACT Monitoring the influence of livestock systems’ on soil quality (SQ) in the Colombian Amazon region is important to ensure the sustainability of those agroecosystems. Here we used the Soil ...Management Assessment Framework (SMAF) to assess the SQ responses to land-use change associated with the adoption of silvopastoral systems (SPS) at two study sites in the Colombian Amazon region. A chronosequence formed by three land-use systems, reflecting the typical land transition performed in the region, was established at each study site: i) native vegetation (NV), ii) pasture (PAST), and iii) SPS. Soil samples were collected at 10 cm deep increments until reaching 30 cm deep. Then soil pH, potassium, available phosphorus, microbial carbon, soil organic carbon, and bulk density were measured. In addition, data from Visual Evaluation of Soil Structure (VESS) were correlated. Data were interpretated using SMAF algorithms, and a Soil Quality Index (SQI) was calculated. Our data showed an SQ degradation due to land-use change from NV to PAST, with soils reducing their capacity of soils function from 0.72 to 0.62. The establishment of SPS over extensive PAST restored soil quality (SQI = 0.69) compared to PAST (both sites), even reaching similar SQI values to those observed in NV at site 1. The SMAF showed to be a potential tool to monitor the SQ in low-fertility soils from the Colombian Amazon region. The VESS scores were also correlated with SMAF - scores, proving to be a simple and complementary tool for farmers to monitor SQ in the Amazon region.
Coffee cultivation is one of the main agricultural activities in Colombia, which increases the well-being of coffee-growing families. In order to determine the impact of coffee production, the ...capital endowment and well-being of coffee-growing families in the municipality of Pitalito, in the south of Colombia, were analyzed using the community capital index (CCI). Likewise, the relationships between the variables were identified through a Pearson correlation analysis, and the increase in well-being was identified and modeled by employing structural equations. The structural equation model showed a suitable fit to the data, indicated by the non-significant value of the χ2 statistic (p = 0.85), a high CFI (0.97), a low RMSEA (<0.001), a low stability index (0.23) and a low variance inflation factor (VIF = 1.42). At the capital level, political capital in synergy with social capital increased the well-being of coffee-growing families; meanwhile, capitals such as natural and physical-built capital did not have the greatest impact on well-being. Political capital variables such as the “possession of the coffee identification card” (CPI), as well as the variable “participates in the activities carried out by the community action board of the village” (PAC), increased by 9.9% and 8.66%, respectively, in the well-being of coffee-growing families measured by the CCI. The social capital variables that boosted the CCI were the benefits of the National Federation of Coffee Growers (FNC) (BFN, %V(variation): 8.32) and associativity (Aso, %V: 7.51). Other variables that make up human capital with high incidence in the CCI were family size (FSi) and the number of people who can read in the family (FLE) with a variation of 9.12% and 8.6%, respectively. However, other variables such as labor cost for disease management (CDM) and labor cost for harvesting (HCL) had no significant effect on the variation of the CCI. It was found that the level of well-being increases due to variables such as associativity and participation in grassroots organizations in the community, such as being a member of the National Federation of Coffee Growers, a quality represented by the possession of a coffee identification card that, in synergy with other variables, reduce inequality and poverty.
In response to the invasion of microorganisms, plants actively balance their resources for growth and defence, thus ensuring their survival. The regulatory mechanisms underlying plant immunity and ...growth operate through complex networks, in which the brassinosteroid phytohormone is one of the central players. In the past decades, a growing number of studies have revealed a multi-layered crosstalk between brassinosteroid-mediated growth and plant immunity. In this Review, by means of the tango metaphor, we immerse ourselves into the intimate relationship between brassinosteroid and plant immune signalling pathways that is tailored by the lifestyle of the pathogen and modulated by other phytohormones. The plasma membrane is the unique stage where brassinosteroid and immune signals are dynamically integrated and where compartmentalization into nanodomains that host distinct protein consortia is crucial for the dance. Shared downstream signalling components and transcription factors relay the tango play to the nucleus to activate the plant defence response and other phytohormonal signalling pathways for the finale. Understanding how brassinosteroid and immune signalling pathways are integrated in plants will help develop strategies to minimize the growth-defence trade-off, a key challenge for crop improvement.
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