Fusarium pathogens are causal agents of several crop diseases and produce harmful mycotoxins resulting in crop and yield reduction worldwide. Among crop diseases, Fusarium wilt, Fusarium head blight, and Fusarium root blight are mostly reported diseases in numerous vegetables, crops, and fruits and have posed pressure on current food production and safety. In addition, the production of mycotoxins further aggravates plant health and causes serious health risks in humans and animals through food chain contamination. Different management practices have been enlisted in this chapter to reduce or eradicate Fusarium wilt in different crops. Interestingly, various mechanisms developed by plants have also been highlighted to fight against Fusarium pathogens and limit the growth of mycotoxins. One of defence mechanisms is plant antioxidant mechanisms to reduce oxidative stress by increasing enzymatic and non-enzymatic antioxidants to maintain cellular homeostasis under Fusarium infection. The other defence response is through hormonal signalling to combat fungal pathogens. Different phytohormones such as salicylic acid, ethylene, jasmonate, abscisic acid, cytokinin, auxin, and other plant secondary metabolites play a crucial part in the reduction of Fusarium growth and inhibit mycotoxin production through defence-related genes. Further, the use of different pre-harvest and post-harvest strategies has been elucidated to enhance plant resistance and growth by decreasing fungal pathogenicity and virulence.

Plants can experience a variety of environmental stresses that significantly impact their fitness and survival. Additionally, biotic stress can harm agriculture, leading to reduced crop yields and economic losses worldwide. As a result, plants have developed defense strategies to combat potential invaders. These strategies involve regulating redox homeostasis. Several studies have documented the positive role of plant antioxidants, including Ascorbate (Asc), under biotic stress conditions. Asc is a multifaceted antioxidant that scavenges ROS, acts as a co-factor for different enzymes, regulates gene expression, and facilitates iron transport. However, little attention has been given to Asc and its transport, regulatory effects, interplay with phytohormones, and involvement in defense processes under biotic stress. Asc interacts with other components of the redox system and phytohormones to activate various defense responses that reduce the growth of plant pathogens and promote plant growth and development under biotic stress conditions. Scientific reports indicate that Asc can significantly contribute to plant resistance against biotic stress through mutual interactions with components of the redox and hormonal systems. This review focuses on the role of Asc in enhancing plant resistance against pathogens. Further research is necessary to gain a more comprehensive understanding of the molecular and cellular regulatory processes involved.

Phytohormones, pivotal regulators of plant growth and development, are increasingly recognized for their multifaceted roles in enhancing crop resilience against environmental stresses. In this review, we provide a comprehensive synthesis of current research on utilizing phytohormones to enhance crop productivity and fortify their defence mechanisms. Initially, we introduce the significance of phytohormones in orchestrating plant growth, followed by their potential utilization in bolstering crop defences against diverse environmental stressors. Our focus then shifts to an in-depth exploration of phytohormones and their pivotal roles in mediating plant defence responses against biotic stressors, particularly insect pests. Furthermore, we highlight the potential impact of phytohormones on agricultural production while underscoring the existing research gaps and limitations hindering their widespread implementation in agricultural practices. Despite the accumulating body of research in this field, the integration of phytohormones into agriculture remains limited. To address this discrepancy, we propose a comprehensive framework for investigating the intricate interplay between phytohormones and sustainable agriculture. This framework advocates for the adoption of novel technologies and methodologies to facilitate the effective deployment of phytohormones in agricultural settings and also emphasizes the need to address existing research limitations through rigorous field studies. By outlining a roadmap for advancing the utilization of phytohormones in agriculture, this review aims to catalyse transformative changes in agricultural practices, fostering sustainability and resilience in agricultural settings.

Salicylic acid (SA) plays a crucial role not only in defence against pathogen attacks, but also in abiotic stress responses. Recently, some key steps of SA signalling outlined the importance of redox state-dependent processes. This study explores the role of glutathione transferases (GSTs) in the transcriptional reprogramming of redox status-related genes in seven-day-old wild type and Atgst mutant Arabidopsis thaliana plants. The timing of redox changes, detected by the redox-sensitive green fluorescent protein (roGFP2), differed in wild type roots treated with 10 μM or 100 μM SA. Our results verified how the applied SA concentrations had different effect on the expression of oxidative stress- and redox-related genes, among them on the expression of AtGSTF8 and AtGSTU19 genes. Lower vitality and less negative E GSH values were specific characteristics of the Atgst mutants compared to the wild type plants throughout the experiment. Changes in the redox potential were only modest in the mutants after SA treatments. A slightly modified gene expression pattern was observed in control conditions and after 1 h of SA treatments in Atgst mutants compared to Col-0 roots. These data originating from the whole roots provide indirect evidence for the role of the investigated AtGSTF8 and AtGSTU19 isoenzymes in the transduction of the redox signal. Our results demonstrate that the investigated Arabidopsis GSTs have a role in maintaining the levels of reactive oxygen species- and redox homeostasis and are involved in transcriptional reprogramming in the roots.

Drought stress is one of the most serious threats to sustainable agriculture and is predicted to be further intensified in the coming decades. Therefore, understanding the mechanism of drought stress tolerance and the development of drought-resilient crops are the major goals at present. In recent years, noncoding microRNAs (miRNAs) have emerged as key regulators of gene expressions under drought stress conditions and are turning out to be the potential candidates that can be targeted to develop drought-resilient crops in the future. miRNAs are known to target and decrease the expression of various genes to govern the drought stress response in plants. In addition, emerging evidence also suggests a regulatory role of long non-coding RNAs (lncRNAs) in the regulation of miRNAs and the expression of their target genes by a process referred as miRNA sponging. In this review, we present the regulatory roles of miRNAs in the modulation of drought-responsive genes along with discussing their biosynthesis and action mechanisms. Additionally, the interactive roles of miRNAs with phytohormone signaling components have also been highlighted to present the global view of miRNA functioning under drought-stress conditions.

Understanding the invasion potential of any plant species is crucial for early detection in habitat conservation, particularly when observing their expansion within their native region. As a test species, we utilised Allium ursinum L., a dominant clonal species in early spring forest floors. We compared the species' germination capacity in native (Hungarian) and non-native (North American) soils, its seedling growth, and competing performances with two co-occurring dominant species, Melica uniflora Retz. and Carex pilosa Scop., in ten soil types and three soil compositions, respectively. Additionally, the competitive interactions of A. ursinum with Convallaria majalis L., a species already introduced in North America, were assessed under three moisture conditions. The results revealed that A. ursinum exhibited enhanced germination in non-native soils, while its shoot growth was most vigorous in control soil. When grown in soils with different co-dominant species, A. ursinum seedlings exhibited varying growth rates, significantly influenced by solar radiation intensity. A. ursinum shoots displayed superior growth in soil collected from C. pilosa stands compared to soil originating from its own stands. Notably, A. ursinum effectively competed against C. majalis in moderate soil moisture conditions. Furthermore, increasing sand content improved the competitive ability of A. ursinum against C. pilosa and M. uniflora. Based on our findings, A. ursinum possesses an invasion potential for particular North American habitats. However, the extent of its potential is dependent upon soil and climatic conditions. Under medium moisture regime, A. ursinum might outcompete the already established C. majalis from its habitats. Additionally, it can potentially displace native species with comparable ecological characteristics, such as C. pilosa and M. uniflora, especially in loose soils. Similar cross-range seed germination, growth, and paired competition experiments with potential competitor species are highly recommended as these can not only elucidate its native range expansion but also various growth scenarios for its agricultural cultivation.

Polyamines (PAs) are essential N-containing polycationic compounds that play a key role in growth and development and abiotic stress tolerance as hub molecules. Their biosynthesis, as well as catabolism, is fundamental to their function in plants. Moreover, there is a strong interconnection of PAs with other important regulatory molecules such as nitric oxide, hydrogen peroxide, and gamma-aminobutyric acid, which also makes PAs essential to plants. Despite enormous literature related to PA function, there is a big gap in our knowledge concerning their precise mode of action in abiotic stress tolerance. The picture is getting more complex as PA content and spectra show distinct alterations depending on the developmental stage, the organ, or the level of stress conditions of plants. Enhancement of abiotic stress tolerance of plants by PAs can be induced by the application of exogenous PAs or modification of their mechanism by transgenic methods. In this chapter, we provide an overview of the functions of different PAs and their crosstalk with other molecules during abiotic stress conditions, and point to those mechanisms that are promising targets to develop abiotic stress-resilient plants contributing to sustainable agriculture and food supply.

Glutathione peroxidases (GPXs) are important antioxidant enzymes in animals. Plants contain GPX-like (GPXL) enzymes, which—in contrast to GPXs—contain cysteine in their active site instead of selenocysteine. Although several studies proved their importance in development and stress responses, their interaction with ethylene (ET) signalling is not known. Our aim was to investigate the involvement of AtGPXL5 in ET biosynthesis and/or signalling using Atgpxl5 mutant and AtGPXL5 cDNA-overexpressing (OX-AtGPXL5) lines. Four-day-old dark-grown Atgpxl5 seedlings had shorter hypocotyls and primary roots, while OX-AtGPXL5 seedlings exhibited a similar phenotype as wild type under normal conditions. Six-week-old OX-AtGPXL5 plants contained less H2O2 and malondialdehyde, but higher polyamine and similar ascorbate- and glutathione contents and redox potential (EGSH) than the Col-0. One-day treatment with the ET-precursor 1-aminocyclopropane-1-carboxylic acid (ACC) induced the activity of glutathione- and thioredoxin peroxidases and some other ROS-processing enzymes. In the Atgpxl5 mutants, the EGSH became more oxidised; parallelly, it produced more ethylene after the ACC treatment than other genotypes. Although the enhanced ET evolution measured in the Atgpxl5 mutant can be the result of the increased ROS level, the altered expression pattern of ET-related genes both in the Atgpxl5 and OX-AtGPXL5 plants suggests the interplay between AtGPXL5 and ethylene signalling.

Glutathione peroxidases (GPXs) are non-heme peroxidases catalyzing the reduction of H2O2 or organic hydroperoxides to water or corresponding alcohols using glutathione (GSH) or thioredoxin (TRX) as a reducing agent. In contrast to animal GPXs, the plant enzymes are non-seleno monomeric proteins that generally utilize TRX more effectively than GSH but can be a putative link between the two main redox systems. Because of the substantial differences compared to non-plant GPXs, use of the GPX-like (GPXL) name was suggested for Arabidopsis enzymes. GPX(L)s not only can protect cells from stress-induced oxidative damages but are crucial components of plant development and growth. Due to fine-tuning the H2O2 metabolism and redox homeostasis, they are involved in the whole life cycle even under normal growth conditions. Significantly new mechanisms were discovered related to their transcriptional, post-transcriptional and post-translational modifications by describing gene regulatory networks, interacting microRNA families, or identifying Lys decrotonylation in enzyme activation. Their involvement in epigenetic mechanisms was evidenced. Detailed genetic, evolutionary, and bio-chemical characterization, and comparison of the main functions of GPXs, demonstrated their species-specific roles. The multisided involvement of GPX(L)s in the regulation of the entire plant life ensure that their significance will be more widely recognized and applied in the future.

Plants are vital components of our ecosystem for a balanced life here on Earth, as a source of both food and oxygen for survival. Recent space exploration has extended the field of plant biology, allowing for future studies on life support farming on distant planets. This exploration will utilize life support technologies for long-term human space flights and settlements. Such longer space missions will depend on the supply of clean air, food, and proper waste management. The ubiquitous force of gravity is known to impact plant growth and development. Despite this, we still have limited knowledge about how plants can sense and adapt to microgravity in space. Thus, the ability of plants to survive in microgravity in space settings becomes an intriguing topic to be investigated in detail. The new knowledge could be applied to provide food for astronaut missions to space and could also teach us more about how plants can adapt to unique environments. Here, we briefly review and discuss the current knowledge about plant gravity-sensing mechanisms and the experimental possibilities to research microgravity-effects on plants either on the Earth or in orbit.

The growth and productivity of plants are largely dependent on the availability of various mineral nutrients, of which some are required at relatively higher concentrations and are termed as macronutrients, while others are required in low amounts and are termed as micronutrients. Both macro- and micro-nutrients are considered as essential elements as their deficiency can result in severe growth defects in plants. Moreover, some of the recent studies have highlighted the role of even non-essential elements in plants. Iodine is one such non-essential element that, at low concentrations, exhibits positive effects on plant growth. In this review, we discuss the effects of iodine on plants including its uptake and transportation, and the current understanding of the pathways responsible for its functioning as a biostimulant. Moreover, we provide evidence that supports the role of iodine as a biostimulant of growth and stress responses in plants. Iodine, in the range of 0.20 to 10 µM, has been documented to regulate the (1) expression of various genes, and (2) activity and structure of various proteins by protein iodination to improve biomass production and defense responses in plants. Further, a growing body of evidence also suggests a role of iodine in the maintenance of ROS homeostasis in plants under normal as well as challenging environmental conditions.

Heavy metal (HM) toxicity has become a global concern in recent years and is imposing a severe threat to the environment and human health. In the case of plants, a higher concentration of HMs, above a threshold, adversely affects cellular metabolism because of the generation of reactive oxygen species (ROS) which target the key biological molecules. Moreover, some of the HMs such as mercury and arsenic, among others, can directly alter the protein/enzyme activities by targeting their –SH group to further impede the cellular metabolism. Particularly, inhibition of photosynthesis has been reported under HM toxicity because HMs trigger the degradation of chlorophyll molecules by enhancing the chlorophyllase activity and by replacing the central Mg ion in the porphyrin ring which affects overall plant growth and yield. Consequently, plants utilize various strategies to mitigate the negative impact of HM toxicity by limiting the uptake of these HMs and their sequestration into the vacuoles with the help of various molecules including proteins such as phytochelatins, metallothionein, compatible solutes, and secondary metabolites. In this comprehensive review, we provided insights towards a wider aspect of HM toxicity, ranging from their negative impact on plant growth to the mechanisms employed by the plants to alleviate the HM toxicity and presented the molecular mechanism of HMs toxicity and sequestration in plants.

OPINION article Front. Plant Sci., 28 June 2021Sec. Plant Physiology https://doi.org/10.3389/fpls.2021.680709

Lipids are important biomolecules; they serve as structural components of partitioning membrane while they are also excellent energy reserves. The storage lipids in oil seeds are an irreplaceable source of nutrition and energy requirement of humans and cattle. During the past decade, an important discovery identified the components and enzyme involved in plant lipid biosynthesis. This understanding helped the scientific community to stand on giant's shoulder and advance into the manipulation of lipid biosynthesis not just to increase the oil content but preferentially improving the fatty acid profile. The targeted exploitation of de novo fatty acid biosynthesis or elongation summarized most of the approaches that have been employed to achieve desirable improvements in oil seed crops. This includes the overexpression of key enzymes from bacterial or plant origin under control of specific promoters. This knowledge translation from understanding the biosynthesis to directional changes in the lipid profile of seed has been partially successful industrially. However, there are still several studies due to publish about improvement in seed oil content and fatty acid profile in crops of economic importance. In this chapter, the authors discuss the most efficient genetic engineering approaches employed to achieve the desirable lipid profile in two major oil seed crops viz. Soybean, and Camelina. These two oil crops are being cultivated globally for feed as well as a biofuel component.

Glutathione transferases (GSTs) play a crucial role in detoxification processes due to the fact of their glutathione (GSH) conjugating activity, and through glutathione peroxidase or dehydroascorbate reductase (DHAR) activities, they influence the redox state of GSH and ascorbate (AsA). The plant-specific tau (GSTU) group is the largest class of Arabidopsis GSTs, and their members are involved in responses to different abiotic stresses. We investigated the effect of salt stress on two-week-old Arabidopsis thaliana wild-type (Col-0), Atgstu19 and Atgstu24 mutant plants after applying 150 mM NaCl for two days. The Atgstu19 seedlings had lower GST activity and vitality both under control conditions and after salt stress than the wild-type, but the level of total ROS was similar to the Col-0 plants. The GST activity of the knockout Atgstu24 mutant was even higher under control conditions compared to the Col-0 plants, while the ROS level and its vitality did not differ significantly from the wild-type. Analysis of the AtGSTU expression pattern revealed that the mutation in a single AtGSTU gene was accompanied by the up- and downregulation of several other AtGSTUs. Moreover, elevated AsA and GSH levels, an altered GSH redox potential and increased DHAR and glutathione reductase activities could help to compensate for the mutation of AtGSTU genes. The observed changes in the mutants suggest that the investigated isoenzymes influence the redox homeostasis under control conditions and after NaCl treatment in Arabidopsis seedlings. These data indicate for the first time the more general role of a temporary shift of redox status as part of GST mechanisms and regulation.

A tiol peroxidázok közé tartozó növényi glutation peroxidáz-szerű enzimek (GPXL-ek) redukált glutation (GSH) vagy tioredoxin elektron donort használva katalizálják a H2O2 vagy egyéb hidroperoxidok vízzé vagy alkohollá történő redukcióját (Navrot és mtsai., 2006). Az Arabidopsis thaliana 8 GPXL izoenzimet tartalmaz, amelyek különböző sejtorganellumokban lokalizáltak és eltérő redox-függő folyamatokban játszanak szerepet. Az AtGPXL5 egy kevéssé ismert plazmamembrán-kapcsolt izoenzim, bár szerepét feltételezték a sóstressz tolerancia kialakításában (Gao és mtsai. 2014). Kísérleteinkben konstitutívan túltermeltettük az AtGPXL5 cDNS-t és a növények fejlődésében és NaCl kezelésre adott válaszában vizsgáltuk az AtGPXL5 szerepét. Vizsgálatainkat AtGPXL5-túltermelő (OX-AtGPXL5) és Atgpxl5 mutáns növények felhasználásával végeztük. Eredményeink alapján az alábbi megállapításokat tettük: 1) A 12 napos Arabidopsis thaliana Atgpxl5 inszerciós mutánsok gyökerében magasabb szuperoxid gyök anion és össz ROS szint található kontroll körülmények között is, mint a vad típusú (Col-0) gyökerekben. A magasabb ROS szint az Atgpxl5 hajtások csökkent életképességét eredményezte. 7 napig tartó 100 mM-os NaCl kezelés tovább emelte a gyökerekben a O2•− mennyiségét, szintje meghaladta a vad típusban kialakultat. Ezek alapján az AtGPXL5 fontos szerepet tölthet be a reaktív oxigénformák homeosztázisában és a sejt életképességének fenntartásában. 2) A hat hetes Atgpxl5 mutáns és OX-AtGPXL5 növények antioxidáns mechanizmusait összehasonlítva jelentős különbségek mutatkoztak. Míg az Atgpxl5 mutánsban több antioxidatív enzim emelkedett aktivitást mutatott, az AtGPXL5-túltermelő növényekben a vad típushoz hasonló aktivitásokat mértünk. Míg az Atgpxl5 növények magasabb glutation peroxidáz (GPOX) aktivitással rendelkeztek, az OX-AtGPXL növényekben a GPOX és TPOX (tioredoxin peroxidáz) aktivitás is a vad típuséval azonos szinten működött. 3) Kontroll körülmények között a GSH tartalom szignifikánsan alacsonyabb volt az Atgpxl5 mutáns gyökerekben, míg az OX-AtGPXL5 hajtásban magasabb. Az alkalmazott sóstressz után az AtGPXL5-túltermelő növények rendelkeztek legmagasabb GSH és legalacsonyabb GSSG szinttel, a GSSG mennyisége az Atgpxl5 mutáns gyökerekben nőtt legnagyobb mértékben. Az OX-AtGPXL5 vonalak számított redukciós potenciál értéke negatívabb volt, mint a Col-0 vad típusé. Az eredmények megerősítették, hogy az AtGPXL5 fehérje szerepet játszik a redox állapot szabályozásában, amelyen keresztül a növekedést és fejlődést is befolyásolhatják. 4) Az AtGPXL5 protein szükséges az Arabidopsis thaliana csíranövények normál növekedéséhez és fejlődéséhez. Hiányában csökkent az elsődleges gyökerek hossza, biomasszája, a rozetta mérete, a hajtások klorofill- és antocián tartalma kontroll körülmények között is. 100 mM NaCl jelenlétében az Atgpxl5 mutáns és a vad típusú növények magjainak csírázása gátlódott, azonban az AtGPXL5 túltermelőké nem. Az OX-AtGPXL5 növények normal fiziológiás körülmények között a vad típushoz hasonló fenotípust mutattak, azonban 100 mM NaCl jelenlétében jobban növekedtek: nagyobb rozetta átmérővel rendelkeztek, a levelek nagyobb konvex területet foglaltak el, magasabb klorofill és antocián tartalommal rendelkeztek, mint a Col-0 és Atgpxl5 mutáns növények. Az Atgpxl5-nél megfigyelt csökkent hajtás- és gyökérnövekedés arra enged következtetni, hogy az AtGPXL5 fehérje szerepet játszik a növények normal növekedésében.

Salinity stress is one of the major threats to agricultural productivity across the globe. Research in the past three decades, therefore, has focused on analyzing the effects of salinity stress on the plants. Evidence gathered over the years supports the role of ethylene as a key regulator of salinity stress tolerance in plants. This gaseous plant hormone regulates many vital cellular processes starting from seed germination to photosynthesis for maintaining the plants' growth and yield under salinity stress. Ethylene modulates salinity stress responses largely via maintaining the homeostasis of Na+/K+, nutrients, and reactive oxygen species (ROS) by inducing antioxidant defense in addition to elevating the assimilation of nitrates and sulfates. Moreover, a cross-talk of ethylene signaling with other phytohormones has also been observed, which collectively regulate the salinity stress responses in plants. The present review provides a comprehensive update on the prospects of ethylene signaling and its cross-talk with other phytohormones to regulate salinity stress tolerance in plants.