Genome wide transcriptome analysis reveals vital role of heat responsive genes in regulatory mechanisms of lentil (Lens culinaris Medikus)

Abstract

The present study reports the role of morphological, physiological and reproductive attributes viz. membrane stability index (MSI), osmolytes accumulations, antioxidants activities and pollen germination for heat stress tolerance in contrasting genotypes. Heat stress increased proline and glycine betaine (GPX) contents, induced superoxide dismutase (SOD), ascorbate peroxidase (APX) and glutathione peroxidase (GPX) activities and resulted in higher MSI in PDL-2 (tolerant) compared to JL-3 (sensitive). In vitro pollen germination of tolerant genotype was higher than sensitive one under heat stress. In vivo stressed pollens of tolerant genotype germinated well on stressed stigma of sensitive genotype, while stressed pollens of sensitive genotype did not germinate on stressed stigma of tolerant genotype. De novo transcriptome analysis of both the genotypes showed that number of contigs ranged from 90,267 to 104,424 for all the samples with N50 ranging from 1,755 to 1,844 bp under heat stress and control conditions. Based on assembled unigenes, 194,178 high-quality Single Nucleotide Polymorphisms (SNPs), 141,050 microsatellites and 7,388 Insertion-deletions (Indels) were detected. Expression of 10 genes was evaluated using quantitative Real Time Polymerase Chain Reaction (RT-qPCR). Comparison of differentially expressed genes (DEGs) under different combinations of heat stress has led to the identification of candidate DEGs and pathways. Changes in expression of physiological and pollen phenotyping related genes were also reaffirmed through transcriptome data. Cell wall and secondary metabolite pathways are found to be majorly affected under heat stress. The findings need further analysis to determine genetic mechanism involved in heat tolerance of lentil.

Breeding, genetics, and genomics for tolerance against terminal heat in lentil: Current status and future directions

“…Therefore, screening methods have been developed for identifying heat tolerant genotypes under natural (field or pot) and controlled (hydroponic and pot assay) conditions in lentil (Kumar et al, 2016; Singh et al, 2017). Naturally, lentil genotypes are grown either in earthen pots or fields under late‐sown conditions in order to coincide the reproductive stage of plants with high temperature (>35°C), and then, traits like pod setting (seed set) and grain yield are used to identify heat tolerant genotypes (Delahunty et al, 2015; Kumar et al, 2016; Singh et al, 2019; Sita, Sehgal, HanumanthaRao, et al, 2017). However, under field conditions, fluctuating day temperature limits to give uniform temperature during reproductive period across the genotypes when they differ in flowering times (Kumar et al, 2016).…”

“…The controlled conditions give precise monitoring of the traits imparting heat tolerance due to availability of uniform and stable high temperature across the growth and development of crop plants (Basu et al, 2015). In lentil, heat tolerant genotypes have been identified on the basis of growth and development of germinating seeds under high temperature in laboratory or hydroponic conditions (Roy, Tucker, & Tester, 2011; Singh et al, 2016, 2019). However, a heat tolerant genotype identified at seedling stage requires its further validation at reproductive stage as heat stress occurs at terminal stage in lentil.…”

“… Source: Sita, Sehgal, HanumanthaRao, et al, 2017; Sita, Sehgal, Kumar, et al, 2017; Bhandari et al, 2016; Kumar, Gupta, et al, 2018; Chakraborty & Pradhan, 2011; Delahunty et al, 2015; Kumar et al, 2016; Singh et al, 2017, 2019.…”

“…However, during the past years, continuous efforts have been made to study the heat stress tolerance in lentil. These studies identified the heat tolerant genotypes and the associated morpho‐physio‐biochemical traits, characterized the heat tolerance at molecular level, and deciphered the genetics and pathways underlying the heat stress tolerance in lentil (Kumar et al, 2016; Singh et al, 2016; Kumar, Basu, et al, 2018; Singh, Singh, Singh, & Pal, 2017; Delahunty et al, 2018; Singh et al, 2019). Also, knowledge of heat stress in lentil is enriching day by day and is becoming available in the public domain.…”

Deep expression scrutiny of juxtaposed wild and cultivated lentil furnishes new insight into aluminium tolerance mechanism

“…evidencing the efficiency of RNA-Seq in molecular mechanism elucidation [6,[9][10][11]. In case of lentil, RNA-Seq has been utilized to develop a reference transcriptome [12] and to reveal differentially expressed genes for drought stress [13], ascochyta blight [14,15], cold stress [16] and heat stress [17] but no such study has been conducted for Al stress so far. Since for comparative transcriptomic analysis, it is essential to select contrasting genotypes, a couple of previous studies, where different Lens species showing variation in morpho-physiological traits under Al stress and wilds separated from cultivars in molecular analysis [7,8] were considered for selection of genotypes.…”