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Harsh, unpredictable environments are known to favor cooperative groups in animals. Whether plants exhibit similar relationships is unknown. Staghorn ferns (Platycerium bifurcatum, Polypodiaceae) are epiphytes that form cooperative groups which build communal water and nutrient 'nests' at the tops of trees, a habitat characterized by water and nutrient stress. We conducted field observations to test whether staghorn ferns continue to live in large, reproductively active groups after they become dislodged from the canopy and fall to the forest floor, where they are less limited by water and nutrient deprivation. To rule out the potentially confounding effects of light limitation on the forest floor, we also conducted a multi-year glasshouse experiment where we transplanted individual plants into soil and onto vertically oriented boards under standardized light conditions. Results from field observations showed that dislodged colonies formed smaller groups that reproduced less than epiphytic colonies. Results from the glasshouse experiment showed that even when growing in full sun, terrestrial individuals tended to remain solitary, while epiphytic individuals tended to recruit new individuals into colonies. Results also showed that plants growing in potting soil and exposed to full sunlight sporulated more heavily than plants growing epiphytically. However, localities that are characterized by both elevated soil and light resources are generally not available to staghorn ferns in the wild, perhaps with the exception of large, epiphytic colonies with well-developed nests at the top of tree canopies. Overall results indicate that the harsh environmental conditions at the tops of trees trigger the formation of colonies in staghorn ferns, similarly to group living animals.

As sessile organisms, plants have evolved complex signaling mechanisms to sense stress and acclimate. This includes the use of reactive oxygen species (ROS) generated during dysfunctional photosynthesis to initiate signaling. One such ROS, singlet oxygen (¹O₂), can trigger retrograde signaling, chloroplast degradation, and programmed cell death. However, the signaling mechanisms are largely unknown. Several proteins (e.g. PUB4, OXI1, EX1) are proposed to play signaling roles across three Arabidopsis thaliana mutants that conditionally accumulate chloroplast ¹O₂ (fluorescent in blue light (flu), chlorina 1 (ch1), and plastid ferrochelatase 2 (fc2)). We previously demonstrated that these mutants reveal at least two chloroplast ¹O₂ signaling pathways (represented by flu and fc2/ch1). Here, we test if the ¹O₂-accumulating lesion mimic mutant, accelerated cell death 2 (acd2), also utilizes these pathways. The pub4-6 allele delayed lesion formation in acd2 and restored photosynthetic efficiency and biomass. Conversely, an oxi1 mutation had no measurable effect on these phenotypes. acd2 mutants were not sensitive to excess light (EL) stress, yet pub4-6 and oxi1 both conferred EL tolerance within the acd2 background, suggesting that EL-induced ¹O₂ signaling pathways are independent from spontaneous lesion formation. Thus, ¹O₂ signaling in acd2 may represent a third (partially overlapping) pathway to control cellular degradation.

Public financial management (PFM) theory suggests that improvements in the allocation, execution, and monitoring of public funds can result in improved sectoral outcomes, including in health. However, the existing literature on the relationship between PFM quality and health outcomes provides limited empirical documentation and insufficient explanation of the mechanics of that relationship. This paper contributes to the literature by estimating the correlation between PFM quality and health outcomes from a sample of sub-Saharan African countries over the period 2005-2018, using a pooled ordinary least squares (OLS) estimator. The analysis uses Public Expenditure and Financial Accountability (PEFA) scores as proxies for PFM quality. The findings indicate that countries with high-quality PFM tended to have the lowest maternal, under-five and noncommunicable diseases (NCDs) mortality. Among the standard PFM dimensions, the one associated with the higher correlation with maternal and under-five mortality was "predictability and control in budget execution." Better PFM quality was significantly associated with a drop in maternal and under-five mortality in countries which allocated a higher proportion of their budget to the health sector. In countries allocating a lower proportion of their budget to health, the correlations between PFM quality and the three mortality indicators were not significant. The negative correlations between PFM quality and maternal and under-five mortality were significant only in countries with more effective governance. These findings support an emphasis on strengthening PFM as a means of improving health service provision and health outcomes.

Plant-specific Rho-type GTPases (ROPs) are master regulators of cell polarity and development. Over the past 30 years, their localization and dynamics have been largely examined with fluorescent proteins fused at the amino terminus without investigating their impact on protein function. The moss Physcomitrium patens genome encodes four rop genes. In this study, we introduce a fluorescent tag at the endogenous amino terminus of ROP4 in wild-type and rop1,2,3 triple mutant via homologous recombination and demonstrate that the fluorescent tag severely impairs ROP4 function and inhibits its localization on the plasma membrane. This phenotype is exacerbated in mutants lacking ROP-related GTPase-activating proteins. By comparing the localization of nonfunctional and functional ROP4 fusion reporters, we provide insight into the mechanism that governs the membrane association of ROPs.

Urbanization alters the natural environment, with broad negative impacts on living organisms. Urbanization can also disrupt plant-pollinator networks by reducing the abundance and diversity of invertebrates. Firstly, I investigated whether the field bindweed (Convolvulus arvensis) is an obligatory entomophilous plant because previous reports were ambiguous. Secondly, I investigated how the obligatory entomophilous plant, field bindweed, responds to urbanization by comparing the flowering duration (anthesis) and the reproductive success of field bindweeds in urban and rural populations. Unlike cross-pollinated flowers and controls, flowers experimentally prevented from pollination and self-pollinated flowers did not produce seeds, suggesting that the field bindweed is self-incompatible and obligatory entomophilous. The abundance of urban pollinators was 5-6 times lower than the abundance of rural pollinators, and flies (Diptera), beetles (Coleoptera) and moths (Lepidoptera) were significantly more negatively influenced by the urban environment than hymenopterans (Hymenoptera). Urban plants showed significantly longer anthesis duration and lower reproductive success than rural plants. Illuminance and low pollinator abundance were negatively associated with the duration of the anthesis, but relative humidity did not affect the anthesis. Prolonged duration of the anthesis may be an adaptation to pollinator scarcity because more prolonged flowering increases the likelihood of pollination. Future research should unravel whether the longer anthesis of urban flowers is determined by behavioral plasticity or by the evolutionary selection of plants with a genetically determined longer anthesis.

MYB transcription factor is one of the largest families in plants. There are more and more studies on plants responding to abiotic stress through MYB transcription factors, but the mechanism of some family members responding to salt stress is unclear. In this study, physiological and transcriptome techniques were used to analyze the effects of the R2R3-MYB transcription factor AtMYB72 on the growth and development, physiological function, and key gene response of Arabidopsis thaliana. Phenotypic observation showed that the damage of overexpression strain was more serious than that of Col-0 after salt treatment, while the mutant strain showed less salt injury symptoms. Under salt stress, the decrease of chlorophyll content, the degree of photoinhibition of photosystem II (PSII) and photosystem I (PSI) and the degree of oxidative damage of overexpressed lines were significantly higher than those of Col-0. Transcriptome data showed that the number of differentially expressed genes (DEGs) induced by salt stress in overexpressed lines was significantly higher than that in Col-0. GO enrichment analysis showed that the response of AtMYB72 to salt stress was mainly by affecting gene expression in cell wall ectoplast, photosystem I and photosystem II, and other biological processes related to photosynthesis. Compared with Col-0, the overexpression of AtMYB72 under salt stress further inhibited the synthesis of chlorophyll a (Chla) and down-regulated most of the genes related to photosynthesis, which made the photosynthetic system more sensitive to salt stress. AtMYB72 also caused the outbreak of reactive oxygen species and the accumulation of malondialdehyde under salt stress, which decreased the activity and gene expression of key enzymes in SOD, POD, and AsA-GSH cycle, thus destroying the ability of antioxidant system to maintain redox balance. AtMYB72 negatively regulates the accumulation of osmotic regulatory substances such as soluble sugar (SS) and soluble protein (SP) in A. thaliana leaves under salt stress, which enhances the sensitivity of Arabidopsis leaves to salt. To sum up, MYB72 negatively regulates the salt tolerance of A. thaliana by destroying the light energy capture, electron transport, and antioxidant capacity of Arabidopsis.

In higher plants, the regulatory roles of cAMP (cyclic adenosine 3',5'-monophosphate) signaling remain elusive until now. Cellular cAMP levels are generally much lower in higher plants than in animals and transiently elevated for triggering downstream signaling events. Moreover, plant adenylate cyclase (AC) activities are found in different moonlighting multifunctional proteins, which may pose additional complications in distinguishing a specific signaling role for cAMP. Here, we have developed rapeseed (Brassica napus L.) transgenic plants that overexpress an inducible plant-origin AC activity for generating high AC levels much like that in animal cells, which served the genetic model disturbing native cAMP signaling as a whole in plants. We found that overexpression of the soluble AC activity had significant impacts on the contents of indole-3-acetic acid (IAA) and stress phytohormones, i.e. jasmonic acid (JA), abscisic acid (ABA), and salicylic acid (SA) in the transgenic plants. Acute induction of the AC activity caused IAA overaccumulation, and upregulation of TAA1 and CYP83B1 in the IAA biosynthesis pathways, but also simultaneously the hyper-induction of PR4 and KIN2 expression indicating activation of JA and ABA signaling pathways. We observed typical overgrowth phenotypes related to IAA excess in the transgenic plants, including significant increases in plant height, internode length, width of leaf blade, petiole length, root length, and fresh shoot biomass, as well as the precocious seed development, as compared to wild-type plants. In addition, we identified a set of 1465 cAMP-responsive genes (CRGs), which are most significantly enriched in plant hormone signal transduction pathway, and function mainly in relevance to hormonal, abiotic and biotic stress responses, as well as growth and development. Collectively, our results support that cAMP elevation impacts phytohormone homeostasis and signaling, and modulates plant growth and development. We proposed that cAMP signaling may be critical in configuring the coordinated regulation of growth and development in higher plants.

Tobacco black shank (TBS), caused by Phytophthora nicotianae, is a severe disease. Plant root exudates play a crucial role in mediating plant-pathogen interactions in the rhizosphere. However, the specific interaction between key secondary metabolites present in root exudates and the mechanisms of disease resistance remains poorly understood. This study conducted a comprehensive comparison via quasi-targeted metabolomic analysis on the root exudate metabolites from the tobacco cultivar Yunyan87 and K326, both before and after inoculation with P. nicotianae. The results showed that the root exudate metabolites changed after P. nicotianae inoculation, and the root exudate metabolites of different tobacco cultivar was significantly different. Furthermore, homovanillic acid, lauric acid, and isoliquiritigenin were identified as potential key compounds for TBS resistance based on their impact on the mycelium growth of the pathogens. The pot experiment showed that isoliquiritigenin reduced the incidence by 55.2%, while lauric acid reduced it by 45.8%. This suggests that isoliquiritigenin and lauric acid have potential applications in the management of TBS. In summary, this study revealed the possible resistance mechanisms of differential metabolites in resistance of commercial tobacco cultivar, and for the first time discovered the inhibitory effects of isoliquiritigenin and homovanillic acid on P. nictianae, and attempt to use plants secondary metabolites of for plant protection.

Root hair, single-celled tubular structures originating from the epidermis, plays a vital role in the uptake of nutrients from the soil by increasing the root surface area. Therefore, optimizing root hair growth is crucial for plants to survive in fluctuating environments. Root hair length is determined by the action of various plant hormones, among which the roles of auxin and ethylene have been extensively studied. However, evidence for the involvement of cytokinins has remained elusive. We recently reported that the cytokinin-activated B-type response regulators, ARABIDOPSIS RESPONSE REGULATOR 1 (ARR1) and ARR12 directly upregulate the expression of ROOT HAIR DEFECTIVE 6-LIKE 4 (RSL4), which encodes a key transcription factor that controls root hair elongation. However, depending on the nutrient availability, it is unknown whether the ARR1/12-RSL4 pathway controls root hair elongation. This study shows that phosphate deficiency induced the expression of RSL4 and increased the root hair length through ARR1/12, though the transcript and protein levels of ARR1/12 did not change. These results indicate that cytokinins, together with other hormones, regulate root hair growth under phosphate starvation conditions.