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.

Brassica spp., commonly known as rapeseed-mustard, plays a significant role in the Indian economy by providing edible oils, vegetables, condiments and animal feed. Globally, India holds second and third position in rapeseed-mustard area under cultivation and production, respectively. However, anthropogenically accelerated climate change thwarts yield potential of rapeseed-mustard by employing abiotic (drought, flood, temperature variation and salinity) and biotic (disease and insects) stresses. Various approaches such as molecular breeding, pre-breeding, −omics and biotechnological interventions have been used to develop varieties for improved yield and oil quality, climate resilient and resistance or tolerance to abiotic and biotic stresses. In this context, this chapter highlighted the different cytoplasmic male sterility (CMS) sources and their potential use for hybrid development. At the end, this chapter also enlisted salient achievement by the government and non-government institutes and briefly described the future perspective for improvement of rapeseed-mustard in India.

Burgeoning the human population with its required food demand created a burden on ever-decreasing cultivated land and our food production systems. This situation prompted plant scientists to breed crops in a short duration with specific traits. Marker-assisted selection (MAS) has emerged as a potential tool to achieve desirable results in plants with the help of molecular markers and improves the traits of interest in a short duration. The MAS has comprehensively been used in plant breeding to characterize germplasm, diversity analysis, trait stacking, gene pyramiding, multi-trait introgression, and genetic purity of different cereals, pulses, oilseeds, and fiber crops, etc. Mapping studies pointed out several marker-trait associations from different crop species, which specifies the potential application of MAS in accelerating crop improvement. This chapter presents an overview of molecular markers, their genesis, and potential use in plant breeding.

Codon usage bias (CUB) phenomenon varies with the species and even within the genes of the same species, where few codons are preferred more frequently than their other synonymous codons. It also categorizes the differences between species. Nucleotide compositional analysis reveals the molecular mechanisms of genes and the evolutionary relationship of a gene in dissimilar plant species. In the present study, three orthologous sequences of each FAE1 (FAE1.1, FAE1.2, and FAE1.3) and FAD2 (FAD2.1, FAD2.2, and FAD2.3) genes, from six Brassica species were accessed using the GenBank database. Further, CUB-related parameters such as nucleotide composition (AT and GC content), relative synonymous codon usage (RSCU), the effective number of codons (ENC), frequency of optimal codons (Fop), relative codon usage bias (RCBS), neutrality plot (GC12 vs. GC3), parity rule-2 [(A3/(A3 + T3) vs. (G3/(G3 + C3)], and correspondence analysis (COA) were analyzed to compare codon bias in U’s triangle Brassica species. The FAE1 genes were AT-biased and FAD2 genes were GC-biased across the studied Brassica species. RSCU values indicated that both the genes had moderate codon usage frequency for selected amino acids. The evolutionary study confirmed that codon usage preference is similar within the species grouped into the same cluster for FAE1; however, B. nigra performed differently for FAD2.2 orthologue. The high ENC value, low Fop, and RSCU value highlighted that FAE1 and FAD2 genes had a low level of gene expression and moderate preference for codon usage across the Brassicas. In addition, neutrality plot, parity rule, and correspondence analysis revealed that natural selection pressure had significantly contributed to CUB for FAE1 genes, whereas mutation and selection pressure occurred for FAD2 genes. This study would help to decode codon optimization, improve the level of expression of exogenous genes, and transgenic engineering to increase fatty acid profiling for the betterment of seed oil in Brassica species.