Understanding aquaporin transport system, silicon and other metalloids uptake and deposition in bottle gourd (Lagenaria siceraria).

Aquaporins (AQPs) facilitates the transport of small solutes like water, urea, carbon dioxide, boron, and silicon (Si) and plays a critical role in important physiological processes. In this study, genome-wide characterization of AQPs was performed in bottle gourd. A total of 36 AQPs were identified in the bottle gourd, which were subsequently analyzed to understand the pore-morphology, exon-intron structure, subcellular-localization. In addition, available transcriptome data was used to study the tissue-specific expression. Several AQPs showed tissue-specific expression, more notably the LsiTIP3-1 having a high level of expression in flowers and fruits. Based on the in-silico prediction of solute specificity, LsiNIP2-1 was predicted to be a Si transporter. Silicon was quantified in different tissues, including root, young leaves, mature leaves, tendrils, and fruits of bottle gourd plants. More than 1.3% Si (d.w.) was observed in bottle gourd leaves, testified the in-silico predictions. Silicon deposition evaluated with an energy-dispersive X-ray coupled with a scanning electron microscope showed a high Si accumulation in the shaft of leaf trichomes. Similarly, co-localization of Si with arsenic and antimony was observed. Expression profiling performed with real-time quantitative PCR showed differential expression of AQPs in response to Si supplementation. The information provided in the present study will be helpful to better understand the AQP transport mechanism, particularly Si and other metalloids transport and localization in plants.

Genome-Wide Analysis and Expression Profiling of Rice Hybrid Proline-Rich Proteins in Response to Biotic and Abiotic Stresses, and Hormone Treatment.

Hybrid proline-rich proteins (HyPRPs) belong to the family of 8-cysteine motif (8CM) containing proteins that play important roles in plant development processes, and tolerance to biotic and abiotic stresses. To gain insight into the rice HyPRPs, we performed a systematic genome-wide analysis and identified 45 OsHyPRP genes encoding 46 OsHyPRP proteins. The phylogenetic relationships of OsHyPRP proteins with monocots (maize, sorghum, and Brachypodium) and a dicot (Arabidopsis) showed clustering of the majority of OsHyPRPs along with those from other monocots, which suggests lineage-specific evolution of monocots HyPRPs. Based on our previous RNA-Seq study, we selected differentially expressed OsHyPRPs genes and used quantitative real-time-PCR (qRT-PCR) to measure their transcriptional responses to biotic (Magnaporthe oryzae) and abiotic (heat, cold, and salt) stresses and hormone treatment (Abscisic acid; ABA, Methyl-Jasmonate; MeJA, and Salicylic acid; SA) in rice blast susceptible Pusa Basmati-1 (PB1) and blast-resistant near-isogenic line PB1+Pi9. The induction of OsHyPRP16 expression in response to the majority of stresses and hormonal treatments was highly correlated with the number of cis-regulatory elements present in its promoter region. In silico docking analysis of OsHyPRP16 showed its interaction with sterols of fungal/protozoan origin. The characterization of the OsHyPRP gene family enables us to recognize the plausible role of OsHyPRP16 in stress tolerance.

A temperature-responsive gene in sorghum encodes a glycine-rich protein that interacts with calmodulin.

Imposition of different biotic and abiotic stress conditions results in an increase in intracellular levels of Ca2+ which is sensed by various sensor proteins. Calmodulin (CaM) is one of the best studied transducers of Ca2+ signals. CaM undergoes conformational changes upon binding to Ca2+ and interacts with different types of proteins, thereby, regulating their activities. The present study reports the cloning and characterization of a sorghum cDNA encoding a protein (SbGRBP) that shows homology to glycine-rich RNA-binding proteins. The expression of SbGRBP in the sorghum seedlings is modulated by heat stress. The SbGRBP protein is localized in the nucleus as well as in cytosol, and shows interaction with CaM that requires the presence of Ca2+. SbGRBP depicts binding to single- and also double-stranded DNA. Fluorescence spectroscopic analyses suggest that interaction of SbGRBP with nucleic acids may be modulated after binding with CaM. To our knowledge, this is the first study to provide evidence for interaction of a stress regulated glycine-rich RNA-binding protein with CaM.