Co-regulation analysis of co-expressed modules under cold and pathogen stress conditions in tomato

Exploring the gene expression network involved in the heat stress response of a thermotolerant tomato genotype

BACKGROUND

The increase in temperatures due to the current climate change dramatically affects crop cultivation, resulting in yield losses and altered fruit quality. Tomato is one of the most extensively grown and consumed horticultural products, and although it can withstand a wide range of climatic conditions, heat stress can affect plant growth and development specially on the reproductive stage, severely influencing the final yield. In the present work, the heat stress response mechanisms of one thermotolerant genotype (E42) were investigated by exploring its regulatory gene network. This was achieved through a promoter analysis based on the identification of the heat stress elements (HSEs) mapping in the promoters, combined with a gene co-expression network analysis aimed at identifying interactions among heat-related genes.

RESULTS

Results highlighted 82 genes presenting HSEs in the promoter and belonging to one of the 52 gene networks obtained by the GCN analysis; 61 of these also interact with heat shock factors (Hsfs). Finally, a list of 13 candidate genes including two Hsfs, nine heat shock proteins (Hsps) and two GDSL esterase/lipase (GELPs) were retrieved by focusing on those E42 genes exhibiting HSEs in the promoters, interacting with Hsfs and showing variants, compared to Heinz reference genome, with HIGH and/or MODERATE impact on the translated protein. Among these, the Gene Ontology annotation analysis evidenced that only LeHsp100 (Solyc02g088610) belongs to a network specifically involved in the response to heat stress.

CONCLUSIONS

As a whole, the combination of bioinformatic analyses carried out on genomic and trascriptomic data available for tomato, together with polymorphisms detected in HS-related genes of the thermotolerant E42 allowed to determine a subset of candidate genes involved in the HS response in tomato. This study provides a novel approach in the investigation of abiotic stress response mechanisms and further studies will be conducted to validate the role of the highlighted genes.

The effects of water deficit on the expression of monoterpene synthases and essential oils composition in Salvia ecotypes

The medicinal sage plant (Salvia spp.), belonging to Lamiaceae family, is one of the most important medicinal and aromatic plants. The members of this genus are globally known due to its antimicrobial, antioxidant, astringent, spasmolytic, antihidrotic and specific sensorial properties. In this study, we investigated the potential impact of water deficit on transcript abundance, and essential oil composition of five major metabolites, i.e. 1-8 cineole, α-β-thujone, camphor, and borneol in three genotypes of Salvia spp. Results showed that relative expression of three genes and their corresponding metabolites increased together at three stages under drought condition, but the CS gene transcript decreased independently from 1,8-cineole in garden sage. Furthermore, borneol changed differently compared to the BS gene expression in control and drought treatment plants of S. reuterana (Yasuj). The competitive synthesis of ß-thujone, and α-thujone by SS gene were demonstrated in S. officinalis and Yasuj ecotype of S. reuterana; whereas, no change was observed for Urmia ecotype of S. reuterana. There was no precursor shortage to synthesis of borneol and camphor in garden sage; however increasing the BS led to high production of borneol and low camphor in S. reuterana under drought stress. As a mechanism, secondary metabolites enable the plants to cope with unfavorable conditions, but genetic differences might affect the quantity and quality of these compounds.

New insights into diosgenin biosynthesis pathway and its regulation in Trigonella foenum-graecum L

INTRODUCTION

Throughout history, thousands of medicinal and aromatic plants have been widely utilised by people worldwide. Owing to them possessing of valuable compounds with little side effects in comparison with chemical drugs, herbs have been of interest to humans for a number of purposes. Diosgenin, driven from fenugreek, Trigonella foenum-graecum L., has extensively drawn scientist's attention owing to having curable properties and being a precursor of steroid hormones synthesis. Nonetheless, complete knowledge about the biosynthesis pathway of this metabolite is still elusive.

OBJECTIVE

In the present research, we isolated the full-length CDS of 14 genes involving in diosgenin formation and measured their expression rate in various genotypes, which had illustrated different amount of diosgenin.

METHODOLOGY

The genes were successfully isolated, and functional motifs were also assessed using in silico approaches.

RESULTS

Moreover, combining transcript and metabolite analysis revealed that there are many genes playing the role in diosgenin formation, some of which are highly influential. Among them, ∆²⁴ -reductase, which converts cycloartenol to cycloartanol, is the first-committed and rate-limiting enzyme in this pathway. Additionally, no transcripts indicating to the presence or expression of lanosterol synthase were detected, contradicting the previous hypothesis about the biosynthetic pathway of diosgenin in fenugreek.

CONCLUSION

Considering all these, therefore, we propose the most possible pathway of diosgenin. This knowledge will then pave the way toward cloning the genes as well as engineering the diosgenin biosynthesis pathway.