European Journal of Sustainable Agroecosystems

Cajanus cajan (L.) Millsp. or Pigeonpea is an important legume crop with important agronomic and nutritional aspects. Soil salinity stress adversely affects pigeonpea productivity due to ionic toxicity, osmotic stress, and oxidative damage. The study of salinity tolerance mechanisms is an important process to enhance development of tolerant cultivars. The current transcriptomic experiment analyzed genome-wide expression patterns taking the salt-tolerant pigeonpea genotype (ICPL-87119) undergoing three types of salinity stress (0 mM, 100 mM, and 200 mM NaCl) as an example. The use of RNA sequencing techniques enabled the identification of 3,847 genes with changed expression taking into account different treatments with salt stress. Functional annotation showed that the increased expression of the genes is connected both with ion transport (SOS1, HKT1, NHX1) and biosynthesis of osmolytes (P5CS, BADH, TPS) as well as transcription factors (DREB, NAC, bZIP) and proteins engaged in antioxidant defense (SOD, CAT, APX). The decreased expression of the genes occurred based on the involvement of photosynthesis and other processes connected with plant development indicating that the allocation of resources is subject to stress conditions. Gene Ontology analysis revealed the existence of 127 enriched processes connected with the response to stress, ion transport, and hormone signaling processes. KEGG analysis demonstrated The scavenging, osmotic adjustment, and transcriptional regulation pathways. The use of weighted gene co-expression network analysis (WGCNA) led to the discovery of 8 co-expression modules that were significantly associated with the salt tolerance trait with a total of 1,240 genes showing differing expression patterns. The assembled transcriptomic, physiological and biochemical data provide a complete molecular model of the salinity adaptation of pigeonpea through Na+ exclusion, K+ compartmentalization, accumulation of osmoprotectants, ABA signaling, and increased antioxidant activity. This transcriptomics dataset could be helpful in the development of salt-tolerant pigeonpea varieties with higher productivity.