Phytohormones (PHs) play crucial role in regulation of various physiological and biochemical processes that govern plant growth and yield under optimal and stress conditions. The interaction of these PHs is crucial for plant survival under stressful environments as they trigger signaling pathways. Hormonal cross regulation initiate a cascade of reactions which finely tune the physiological processes in plant architecture that help plant to grow under suboptimal growth conditions. Recently, various studies have highlighted the role of PHs such as abscisic acid, salicylic acid, ethylene, and jasmonates in the plant responses toward environmental stresses. The involvement of cytokinins, gibberellins, auxin, and relatively novel PHs such as strigolactones and brassinosteroids in plant growth and development has been documented under normal and stress conditions. The recent identification of the first plant melatonin receptor opened the door to this regulatory molecule being considered a new plant hormone. However, polyamines, which are not considered PHs, have been included in this chapter. Various microbes produce and secrete hormones which helped the plants in nutrient uptake such as N, P, and Fe. Exogenous use of such microbes help plants in correcting nutrient deficiency under abiotic stresses. This chapter focused on the recent developments in the knowledge related to PHs and their involvement in abiotic stresses of anticipation, signaling, cross-talk, and activation of response mechanisms. In view of role of hormones and capability of microbes in producing hormones, we propose the use of hormones and microbes as potential strategy for crop stress management.

In the era of rapid climate change, abiotic stresses are the primary cause for yield gap in major agricultural crops. Among them, salinity is considered a calamitous stress due to its global distribution and consequences. Salinity affects plant processes and growth by imposing osmotic stress and destroys ionic and redox signaling. It also affects phytohormone homeostasis, which leads to oxidative stress and eventually imbalances metabolic activity. In this situation, signaling compound crosstalk such as gasotransmitters [nitric oxide (NO), hydrogen sulfide (H2S), hydrogen peroxide (H2O2), calcium (Ca), reactive oxygen species (ROS)] and plant growth regulators (auxin, ethylene, abscisic acid, and salicylic acid) have a decisive role in regulating plant stress signaling and administer unfavorable circumstances including salinity stress. Moreover, recent significant progress in omics techniques (transcriptomics, genomics, proteomics, and metabolomics) have helped to reinforce the deep understanding of molecular insight in multiple stress tolerance. Currently, there is very little information on gasotransmitters and plant growth regulator crosstalk and inadequacy of information regarding the integration of multi-omics technology during salinity stress. Therefore, there is an urgent need to understand the crucial cell signaling crosstalk mechanisms and integrative multi-omics techniques to provide a more direct approach for salinity stress tolerance. To address the above-mentioned words, this review covers the common mechanisms of signaling compounds and role of different signaling crosstalk under salinity stress tolerance. Thereafter, we mention the integration of different omics technology and compile recent information with respect to salinity stress tolerance.

Accelerated crop growth strategy innovations are required as we reach saturation peaks regarding the productivity of major food crops. Speed breeding (SB) is one of the most promising technologies adopted for this purpose. SB hastens crop production by reducing plant growth and development, breeding time and swift generation advancement. Prolonged daily light exposure shortens the life cycle in some long-day or day-neutral plants leading to early seed harvest. This approach is best suited for controlled environment prebreeding/breeding activities and analysed for several crop species. SB can be integrated with different traditional and advanced genomicsassisted breeding technologies like marker-assisted selection (MAS), genomic selection (GS), pollen-based selection (PBS), overexpression/knock-down transgenics and genome editing to achieve more precise and faster results on translational genetic enhancement. This review will discuss the approaches and strategies adopted for the SB and its potential to integrate existing crop improvement technologies to attain more efficient outcomes on major food crops' varietal improvement.

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Nitric oxide (NO) is a free-radical gasotransmitter signaling molecule associated with a varied spectrum of signal transduction pathways linked to inducing cross-adaptation against abiotic stresses. It has crucial roles from seed germination to plant maturity, depending upon its cellular concentration. The functional cross-talk of NO among different stress signaling cascades leads to alteration in the expression of developmental genes that regulate biosynthesis and function of plant growth regulators (PGRs). NO-PGRs and secondary signaling compounds cross-talk trigger reprogramming of stress-responsive gene expressions, transcriptional gene modulations, redox regulating machinery, oxidative metabolisms, and multiple regulatory pathways under plant abiotic stress. Recent findings suggest NO as critical components of numerous plant signaling network that interplays with auxin, gibberellins (GA), abscisic acid (ABA), ethylene (ET), jasmonic acid (JA), brassinosteroids (BRs), H 2 O 2 , melatonin, hydrogen sulfide (H 2 S), salicylic acid (SA), and other PGRs to modulate growth and development under multiple stresses. Considering the importance of NO signaling crosstalk under stress adaptation, in this review, we point out the biosynthesis and metabolism of NO and its crosstalk with numerous other signaling compounds. Further, recent cellular and molecular advances in NO signaling cross-talk under abiotic stress adaptations also have been discussed.

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