Dear Colleagues,

Reprogramming of metabolic pathways during plant growth and development is well documented in the literature. However, the environmental biotic and abiotic stimuli extort changes in plant primary and secondary metabolites and functioning of various physiological processes. Plant pathogens, i.e., viruses, bacteria, and fungi causing diseases, trigger different immune responses and influence the physiological state of host plants. Similarly, abiotic stresses such as heavy metals, fluctuation of temperature, light intensity, or deficiency in macro- and micronutrients can cause changes in plant physiological processes, redirecting them to defensive mode. Moreover, so-called cross-stress or multistress, caused by the simultaneous influence of more than one stress factor, e.g., combination of biotic and abiotic stresses, can also affect plant physiology.

We welcome original research papers and reviews on all aspects of plant physiology under the influence of various biotic and/or abiotic stresses.

Dr. Violetta Macioszek
Prof. Dr. Iwona Ciereszko
Prof. Dr. Andrzej Kiejstut Kononowicz
Guest Editors

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• biotic and abiotic stresses
• plant physiology
• plant disease
• photosynthesis
• primary and secondary metabolites
• plant hormones
• plant pathogens

Title: Genetic Regulation in Response to Combinatorial Stress in Plants
Authors: Ritesh Kumar
Affiliation: Boyce Thompson Institute, Ithaca, NY, USA
Abstract: In this review, I will summaries the role of different genes linked with both biotic and abiotic stress tolerance as a part of introduction. Then I will access available RNA-seq datasets based on plant response to different stresses, then I will fetch out the common genes and finally discuss the possible role of the mined genes of plants in mitigating future combinatorial stress problem.

Title: Drought Stress in the Epiphytic Fern Platycerium bifurcatum: Insight into Photosynthetic Response
Authors: Jakub Oliwa; Andrzej Skoczowski; Andrzej Kornaś
Affiliation: Institute of Biology, Pedagogical University in Krakow, Podchorążych 2, 30-084 Kraków, Poland
Abstract: Progressive climate changes cause disturbance of water relations in tropical rainforests, where epiphytic ferns are an important element of biodiversity. In these plants, the efficiency of photosynthesis is closely related to the efficiency of water transport. In addition, due to the lack of contact with the soil, epiphytes are extremely susceptible to drought stress. Knowledge about the physiology of epiphytic ferns is still fragmentary and few studies have been conducted on the photochemical reactions of photosynthesis in response to abiotic stress in this group of plants. The aim of the study was to investigate the functioning of photosynthetic apparatus of Platycerium bifurcatum epiphytic fern during a 6-week period of water deficit. The hydration and pigment composition of leaves were determined by measuring the reflectance. Chlorophyll a fluorescence kinetics parameters, fluorescence induction curves (OJIP), low-temperature fluorescence curves at 77K and proline concentration were analyzed at seven time points. After a decrease in leaf hydration by 10-15%, there were disturbances in the oxidation-reduction balance (especially in the initial photochemical reactions of photosynthesis), a rapid decrease in plant vitality (PI) and significant fluctuations in chlorophyll a fluorescence parameters (Fv/Fm, Fv/F0, RC/ABS). The relative size of photosystem I antenna structures compared to photosystem II increased in the following weeks of drought. Changes in photochemical reactions were accompanied by a decrease in net photosynthesis and transpiration as well as an increase in proline concentration.

Title: Effect of Glyphosate Herbicide on Eucalyptus Seedlings Infected with Ralstonia solanacearum
Authors: Ana Carolina Firmino
Affiliation: College of Agricultural and Technological Sciences, São Paulo State University (Unesp), Dracena 17900-000, Brazil
Abstract: Bearing in mind that glyphosate is a herbicide used in eucalyptus cultivation in the field, and can leave residues in forest soils, and that the bacterium Ralstonia solanacearum is an important pathogen in this culture because it causes bacterial wilt, possessing the ability to interact with elements present in the soil where it lives, the objective of the research was to analyze the behavior of eucalyptus plants in soil infested with R. solanacearum containing different doses of glyphosate. The experiments were carried out from the preparation and inoculation of bacterial solution in sterile soil, treated with different doses of the herbicide (0; 0.36; 0.72; 1.44; 2.88 and 5.76 mg e.a/L). The experimental design used was completely randomized, with 10 replications per treatment, totaling 60 experimental plots. Being repeated twice. Analysis of the activity of peroxidase and phenylalanine ammonia-lyase (FAL) enzymes, plant height, biomass and SPAD index was carried out. In addition, quantification of the bacterial population of soil samples from treatments in different periods was performed. To complement the analyzes, a second experiment was set up, which included the same soil preparation and treatments to analyze soil respiration with bacteria and herbicide doses, in the absence of the plant, for 50 days. The experimental design was completely randomized, with 4 replications per treatment, totaling 24 plots. The results showed that the glyphosate doses interfered in the enzymatic activity of both analyzed enzymes, and the FAL activity was greater as the product doses increased. About height, biomass and SPAD index, there was none between treatments. The results obtained showed that glyphosate can increase R. solanacearum populations present in soils. The presence of glyphosate showed an increase in soil respiration in the treatment of 2.88 mg e.a/L. The analyzes carried out showed that the use of glyphosate in the eucalyptus culture presented interactions with the defense mechanisms of the plant and with R. solanacearum, requiring further studies.