Anirban Bhar

Lignification is a central process affecting plant growth, development, and stress responses. An intricate network of hormonal signals tightly regulates these processes. Several phytohormones have been demonstrated to function as important modulators of the lignin biosynthesis pathway, but their crosstalk is largely elusive. Increasing evidence of hierarchical transcriptional networks in lignification and the interaction of transcriptional regulation with different phytohormones highlights the need to emphasize this critical regulatory aspect of lignification. The hormones adjust lignification by modifying gene expression, enzyme activity, and the interaction between different metabolic pathways. This review summarizes the status of the principal hormonal control of lignification, and also accentuates hormonal crosstalk and transcriptional control. Additionally, the role of reactive oxygen species in linking lignification with hormonal regulation is discussed. This review not only contributes to basic plant biology, but also paves the way for the development of crops with improved stress tolerance and specialized lignin qualities for industrial applications.

The sessile nature of plants and complete absence of humoral immunity equips them with complex mechanism of resilience against diverse stress factors. The innate immune system in plants mostly utilises transcriptional reprogramming during stress exposures. Biotic interactions in plants require multifaceted gene expressional plasticity due to constant co-evolutionary arms-race between the plants and pathogen. Classical ‘zig-zag’ model of plant immunity reports biphasic induction of immune response in plant–microbe interaction. Reactive oxygen species (ROS) and salicylic acid (SA) play central roles in pathogen associated molecular pattern triggered immunity and effector triggered immunity. Role of SA in modulating defence signalling pathway and activating systemic acquired resistance is well established in model and crop plants. However, integration of SA-mediated defence signalling pathways in developing sustainable resistance response is still scarce. SA-mediated immune signalling in plants is not mutually exclusive and relies on highly coordinated transcriptional overlaps and hormonal crosstalk. This review discusses about SA biosynthesis, its evolutionary perspective, the signalling overlaps of salicylic acid with ROS, other plant hormones and also their roles in transgenerational priming. We decipher the integral SA signalling nodes during in planta infection, which could be utilised in future crop management programmes.

Anthropogenic activities and subsequent global climate change instigate drastic crop productivity and yield changes. These changes comprise a rise in the number and severity of plant stress factors, which can arise simultaneously or sequentially. When abiotic stress factors are combined, their impact on plants is more substantial than that of a singleton stress factor. One such impact is the alteration of redox cellular homeostasis, which, in turn, can regulate downstream stress-responsive gene expression and resistance response. The epigenetic regulation of gene expression in response to varied stress factors is an interesting phenomenon, which, conversely, can be stable and heritable. The epigenetic control in plants in response to abiotic stress combinations and their interactions with cellular redox alteration is an emerging field to commemorate crop yield management under climate change. The article highlights the integration of the redox signaling pathways and epigenetic regulations as pivotal components in the complex network of plant responses against multi-combinatorial stresses across time and space. This review aims to lay the foundation for developing novel approaches to mitigate the impact of environmental stresses on crop productivity, bridging the gap between theoretical understanding and practical solutions in the face of a changing climate and anthropogenic disturbances.

The rhizosphere is the hotspot for microbial enzyme activities and contributes to carbon cycling. Precipitation is an important component of global climate change that can profoundly alter belowground microbial communities. However, the impact of precipitation on conifer rhizospheric microbial populations has not been investigated in detail. In the present study, using high-throughput amplicon sequencing, we investigated the impact of precipitation on the rhizospheric soil microbial communities in two Norway Spruce clonal seed orchards, Lipová Lhota (L-site) and Prenet (P-site). P-site has received nearly double the precipitation than L-site for the last three decades. P-site documented higher soil water content with a significantly higher abundance of Aluminium (Al), Iron (Fe), Phosphorous (P), and Sulphur (S) than L-site. Rhizospheric soil metabolite profiling revealed an increased abundance of acids, carbohydrates, fatty acids, and alcohols in P-site. There was variance in the relative abundance of distinct microbiomes between the sites. A higher abundance of Proteobacteria, Acidobacteriota, Ascomycota, and Mortiellomycota was observed in P-site receiving high precipitation, while Bacteroidota, Actinobacteria, Chloroflexi, Firmicutes, Gemmatimonadota, and Basidiomycota were prevalent in L-site. The higher clustering coefficient of the microbial network in P-site suggested that the microbial community structure is highly interconnected and tends to cluster closely. The current study unveils the impact of precipitation variations on the spruce rhizospheric microbial association and opens new avenues for understanding the impact of global change on conifer rizospheric microbial associations.