Exploring the structural assembly of rice ADP-glucose pyrophosphorylase subunits using MD simulation.

ADP-glucose pyrophosphorylase plays a pivotal role as an allosteric enzyme, essential for starch biosynthesis in plants. The higher plant AGPase comparises of a pair of large and a pair of small subunits to form a heterotetrameric complex. Growing evidence indicates that each subunit plays a distinct role in regulating the underlying mechanism of starch biosynthesis. In the rice genome, there are four large subunit genes (OsL1-L4) and three small subunit genes (OsS1, OsS2a, and OsS2b). While the structural assembly of cytosolic rice AGPase subunits (OsL2:OsS2b) has been elucidated, there is currently no such documented research available for plastidial rice AGPases (OsL1:OsS1). In this study, we employed protein modeling and MD simulation approaches to gain insights into the structural association of plastidial rice AGPase subunits. Our results demonstrate that the heterotetrameric association of OsL1:OsS1 is very similar to that of cytosolic OsL2:OsS2b and potato AGPase heterotetramer (StLS:StSS). Moreover, the yeast-two-hybrid results on OsL1:OsS1, which resemble StLS:StSS, suggest a differential protein assembly for OsL2:OsS2b. Thus, the regulatory and catalytic mechanisms for plastidial AGPases (OsL1:OsS1) could be different in rice culm and developing endosperm compared to those of OsL2:OsS2b, which are predominantly found in rice endosperm.

SlHyPRP1 and DEA1, the multiple stress responsive eight-cysteine motif family genes of tomato (Solanum lycopersicum L.) are expressed tissue specifically, localize and interact at cytoplasm and plasma membrane in vivo.

Owing to rapid global climate change, the occurrence of multiple abiotic stresses is known to influence the outburst of biotic stress factors which affects crop productivity. Therefore, it is essential to understand the molecular and cell biology of key genes associated with multiple stress responses in crop plants. SlHyPRP1 and DEA1, the members of eight-cysteine motif (8CM) family genes have been recently identified as putative regulators of multiple stress responses in tomato (Solanum lycopersicum L.). In order to gain deeper insight into cell and molecular biology of SlHyPRP1 and DEA1, we performed their expression analysis in three tomato cultivars and in vivo cell biological analysis. The semi-quantitative PCR and qRT-PCR results showed the higher expression of SlHyPRP1 and DEA1 in leaf, stem, flower and root tissues as compared to fruit and seed tissues in all three cultivars. The expression levels of SlHyPRP1 and DEA1 were found to be relatively higher in a wilt susceptible tomato cultivar (Arka Vikas) than a multiple disease resistant cultivar (Arka Abhed). In vivo cell biological analysis through Gateway cloning and Bi-FC assay revealed the predominant sub-cellular localization and strong protein-protein interaction of SlHyPRP1 and DEA1 at the cytoplasm and plasma membrane. Moreover, SlHyPRP1 showed in vivo interaction with stress responsive proteins WRKY3 and MST1. Our findings suggest that SlHyPRP1 with DEA1 are co-expressed with tissue specificity and might function together by association with WRKY3 and MST1 in plasma membrane for regulating multiple stress responses in the tomato plant.

Ethylene Response Factor (ERF) Family Proteins in Abiotic Stresses and CRISPR-Cas9 Genome Editing of ERFs for Multiple Abiotic Stress Tolerance in Crop Plants: A Review.

Abiotic stresses such as extreme heat, cold, drought, and salt have brought alteration in plant growth and development, threatening crop yield and quality leading to global food insecurity. Many factors plays crucial role in regulating various plant growth and developmental processes during abiotic stresses. Ethylene response factors (ERFs) are AP2/ERF superfamily proteins belonging to the largest family of transcription factors known to participate during multiple abiotic stress tolerance such as salt, drought, heat, and cold with well-conserved DNA-binding domain. Several extensive studies were conducted on many ERF family proteins in plant species through over-expression and transgenics. However, studies on ERF family proteins with negative regulatory functions are very few. In this review article, we have summarized the mechanism and role of recently studied AP2/ERF-type transcription factors in different abiotic stress responses. We have comprehensively discussed the application of advanced ground-breaking genome engineering tool, CRISPR/Cas9, to edit specific ERFs. We have also highlighted our on-going and published R&D efforts on multiplex CRISPR/Cas9 genome editing of negative regulatory genes for multiple abiotic stress responses in plant and crop models. The overall aim of this review is to highlight the importance of CRISPR/Cas9 and ERFs in developing sustainable multiple abiotic stress tolerance in crop plants.