Plants are constantly exposed to adverse environmental factors such as salt, drought, and cold, that have a significant influence on geographical distribution, proliferation, growth, and plant production. Plants respond to external stressors through a complex set of tolerance strategies that are activated and incorporated by the expression of thousands of genes (Seki et al., 2002). Such stressors induced the production of genes that were discovered to be important in the plant's stress resistance. These gene products act as regulatory proteins, increasing stress tolerance in the plant.
The study of transcriptional regulators is a heated issue in genetic sciences now. Transcription factors influence a range of activities, including physical, biochemical, and evolutionary activities, as well as the activation routes of downstream genes. Numerous transcription factors that control dehydration, high salt, and other environmental variables have been identified in recent years. In addition, genomic data study may be utilized to develop an interpretative layout for gene transformation technology, that can be employed to generate highly resistant transgenic organisms.
Dirigent molecules are a multigene family in plants that responds to pathogen resistance (Li et al., 2014)(Liao et al., 2016)(Jin-long et al., 2012). They serve an essential function in improving stress tolerance in many crops (S. Ralph et al., 2006). DIRs and their homolog have been found in all vascular plants (Davin & Lewis, 2000), and they are thought to play a role in lignin and lignan production (Kim et al., 2002). Varying plant species have different numbers of DIR genes. There have already been reports of 25 DIRs in Arabidopsis, 19 DIRs in I. indigotica, 54 DIRs in rice, 35 DIRs in Picea glauca, and 29 DIRs in B. Rapa (Thamil Arasan et al., 2013)(S. Ralph et al., 2006) (S. G. Ralph et al., 2007) (Li et al., 2014). There has never been a genome-wide identification and characterization of DIR in Solanum lycopersicum before. In this work, we discovered 31 SlDIRs in the Solanum lycopersicum genome. Five well-conserved motifs were identified in the amino acid sequence alignments of all 31 SlDIRs, which is like earlier studies9,11,27,29. Only 16% of SlDIRs had one intron, according to the strength and function. The amino acid (aa) sequences varied from 60 aa (SlDIR23) to 399 aa, according to the ORFs assessment (SlDIR11).
The chromosomal positions indicated that SlDIRs were detected on all 12 chromosomes of Solanum lycopersicum but 3, with chromosome 10 having the most SlDIRs and chromosomes 5,9,11,12 having only one DIR gene in their loci.
The architecture of the DIR proteins discovered in this work, as well as the described earlier DIR genes of A. thaliana and poplar, are basic, with very few introns (Khan et al. 2018). Nevertheless, 1–5 introns are found in one-third of rice genome (Liao et al. 2017). This implies that after divergence, rice, Solanum lycopersicum, poplar, and Arabidopsis may well have divergent paths.
Our findings support previous research on cis-element analyses, with elements linked to stress and light being discovered in the upstream region, demonstrating that environmental stress and light may have a regulatory function in SlDIRs. Furthermore, components sensitive to SA and MeJA have been discovered upstream of a large number of SlDIRs. Gibberellin responsive domains were discovered in the majority of DIR genes, which was surprising. All of the findings suggest that the rhythms of SlDIR's hormone responses are extremely complicated. Distinct DIRs are considered to imply multiple functions in a diverse setting at various times, nevertheless, they still need to be examined further in lab to demonstrate their functionality.