An insight into Pisum sativum HSF gene family-Genome-wide identification, phylogenetic, expression, and analysis of transactivation potential of pea heat shock transcription factor.

Field pea (Pisum sativum L, 2n = 14) is a popular temperate legume with high economic value. Heat shock factors (HSFs) are the core element in the regulatory mechanism of heat stress responses. HSFs in pea (P. sativum) have not been characterized and their role remains unclear in different abiotic stresses. To address this knowledge gap, the current study aimed to characterize the HSF gene family in pea. We identified 38 PsHsf members in P. sativum, which are distributed on the seven chromosomes, and based on phylogenetic analysis, we classified them into three representative classes i.e. A, B, and C. Conserved motif and gene structure analysis confirmed a high degree of similarity among the members of the same class. Additionally, identified cis-acting regulatory elements (CAREs) related to abiotic responses, development, growth, and hormone signaling provides crucial insights into the regulatory mechanisms of PsHsfs. Our research revealed instances of gene duplication in PsHsf gene family, suggesting that this mechanism could be driving the expansion of the PsHsf gene family. Moreover, Expression analysis of PsHsfs exhibited upregulation under heat stress (HS), salt stress (SS), and drought stress (DS) showing their phenomenal role in stress conditions. PsHsfs protein interaction network suggested their involvement in stress-responsive mechanisms. Further transactivation potential was checked for spliced variant of PsHsfA2a (PsHsfA2aI, PsHsfA2aII, and PsHsfA2aIII), PsHsfA3, PsHsfA6b, PsHsfA9, PsHsfB1a, and PsHsfB2a. Overall, these findings provide valuable insight into the evolutionary relationship of PsHsf gene family and their role in abiotic stress responses.

PRpnp, a novel dual activity PNP family protein improves plant vigour and confers multiple stress tolerance in Citrus aurantifolia.

Under field conditions, plants are often simultaneously exposed to several abiotic and biotic stresses resulting in significant reductions in growth and yield; thus, developing a multi-stress tolerant variety is imperative. Previously, we reported the neofunctionalization of a novel PNP family protein, Putranjiva roxburghii purine nucleoside phosphorylase (PRpnp) to trypsin inhibitor to cater to the needs of plant defence. However, to date, no study has revealed the potential role and mechanism of either member of this protein group in plant defence. Here, we overexpressed PRpnp in Citrus aurantifolia which showed nuclear-cytoplasmic localization, where it functions in maintaining the intracellular purine reservoir. Overexpression of PRpnp significantly enhanced tolerance to salt, oxidative stress, alkaline pH, drought and two pests, Papilio demoleus and Scirtothrips citri in transgenic plants. Global gene expression studies revealed that PRpnp overexpression up-regulated differentially expressed genes (DEGs) related to ABA- and JA-biosynthesis and signalling, plant defence, growth and development. LC-MS/MS analysis validated higher endogenous ABA and JA accumulation in transgenic plants. Taken together, our results suggest that PRpnp functions by enhancing the endogenous ABA and JA, which interact synergistically and it also inhibits trypsin proteases in the insect gut. Also, like other purine salvage genes, PRpnp also regulates CK metabolism and increases the levels of CK-free bases in transgenic Mexican lime. We also suggest that PRpnp can be used as a potential candidate to develop new varieties with improved plant vigour and enhanced multiple stress resistance.

Genome-wide identification of Aux/IAA and ARF gene families in bread wheat (Triticum aestivum L.).

Wheat (Triticum aestivum L.) is one of the most important food crops in the world. Somatic embryogenesis is an event that is triggered by the presence of auxin hormone for the induction of somatic cells to get converted to embryonic cells. Somatic embryogenesis represents the most important process of totipotency of plants. The role of auxins is widely understood during various stages of embryogenesis including polarity establishment, de-differentiation, re-differentiations, and morphogenesis. Many of the Aux/IAAs and ARFs which are part of auxin signaling components have been identified to play various roles during embryogenesis. In this analysis, the Aux/IAAs and ARFs of T. aestivum have been analyzed at the genome-scale; their structure, function, and evolutionary relatedness were determined. Several Aux/IAAs and ARFs components of T. aestivum have been found to exclusively regulate axis formation, meristem commitment, and other re-differentiation processes by differential expression studies.

Decoding the wheat awn transcriptome and overexpressing TaRca1ß in rice for heat stress tolerance.

KEY MESSAGE: Role of Rubisco Activase in imparting thermotolerance to the photosynthetic apparatus under high temperature. Thus, to improve the grain filling, we need to fine tune these crucial enzymes and their regulation, which directly or indirectly affect spike photosynthesis. CO2 fixation in cereals crops like bread wheat (Triticum aestivum L.) is also contributed by ear photosynthesis beside the other organs like leaves or the flag leaf. 1000-grain weight of three Indian wheat cultivars (cvs.) PBW343, K7903, and HD2329 were calculated under three treatments until maturity stage (i.e. removal of flag leaf, removal of awns and shaded spikes). We observed that awn removal showed a significant decrease in 1000-grain weight in all cultivars. To delve deeper into the biological and molecular pathways taking place underlying the awn physiology, we conducted the awn transcriptome analysis of thermosusceptible Indian wheat cv. PBW343 under heat stress (HS) at 42 °C for 2 h using RNA-sequencing (RNA-seq). Differential expression analysis revealed, 160 transcripts, out of these, 143 transcripts were significantly upregulated and 17 transcripts were repressed under HS conditions. Of these Rca1ß was selected for characterization and overexpression studies. Ectopic expression of TaRca1ß in rice transgenics indicate a direct correlation with tolerance under HS conditions. TaRca1ß provides a better photosynthate energy partitioning under HS with a significant reduction in the non-photochemical fluorescence quenching of the photosynthetic machinery.

Role of myo-inositol during skotomorphogenesis in Arabidopsis.

Myo-inositol is a ubiquitous metabolite of plants. It is synthesized by a highly conserved enzyme L-myo-inositol phosphate synthase (MIPS; EC 5.5.1.4). Myo-inositol is well characterized during abiotic stress tolerance but its role during growth and development is unclear. In this study, we demonstrate that the apical hook maintenance and hypocotyl growth depend on myo-inositol. We discovered the myo-inositol role during hook formation and its maintenance via ethylene pathway in Arabidopsis by supplementation assays and qPCR. Our results suggest an essential requirement of myo-inositol for mediating the ethylene response and its interaction with brassinosteroid to regulate the skotomorphogenesis. A model is proposed outlining how MIPS regulates apical hook formation and hypocotyl growth.

Wheat Myo-inositol phosphate synthase influences plant growth and stress responses via ethylene mediated signaling.

L-myo-inositol phosphate synthase (MIPS; EC 5.5.1.4) is involved in abiotic stress tolerance, however its disruption and overexpression has also been associated with enhanced tolerance to pathogens. The molecular mechanism underlying the role of MIPS in growth, immunity and abiotic stress tolerance remains uncharacterized. We explore the molecular mechanism of MIPS action during growth and heat stress conditions. We raised and characterized the TaMIPS over-expressing rice transgenics which showed a reduced reproductive potential. Transcriptome analysis of overexpression transgenics revealed the activation of ET/JA dependent immune response. Pull-down analysis revealed the interaction of TaMIPS-B with ethylene related proteins. Our results suggest an essential requirement of MIPS for mediating the ethylene response and regulate the growth. A model is proposed outlining how fine tuning of MIPS regulate growth and stress tolerance of the plant.