Chickpea (Cicer arietinum) PHO1 family members function redundantly in Pi transport and root nodulation

Phosphorus (P), a macronutrient, plays key roles in plant growth, development, and yield. Phosphate (Pi) transporters (PHTs) and PHOSPHATE1 (PHO1) are central to Pi acquisition and distribution. Potentially, PHO1 is also involved in signal transduction under low P. The current study was designed to identify and functionally characterize the PHO1 gene family in chickpea (CaPHO1s). Five CaPHO1 genes were identified through a comprehensive genome-wide search. Phylogenetically, CaPHO1s formed two clades, and protein sequence analyses confirmed the presence of conserved domains. CaPHO1s are expressed in different plant organs including root nodules and are induced by Pi-limiting conditions. Functional complementation of atpho1 mutant with three CaPHO1 members, CaPHO1, CaPHO1;like, and CaPHO1;H1, independently demonstrated their role in root to shoot Pi transport, and their redundant functions. To further validate this, we raised independent RNA-interference (RNAi) lines of CaPHO1, CaPHO1;like, and CaPHO1;H1 along with triple mutant line in chickpea. While single gene RNAi lines behaved just like WT, triple knock-down RNAi lines (capho1/like/h1) showed reduced shoot growth and shoot Pi content. Lastly, we showed that CaPHO1s are involved in root nodule development and Pi content. Our findings suggest that CaPHO1 members function redundantly in root to shoot Pi export and root nodule development in chickpea.

Dissecting chickpea genomic loci associated with the root penetration responsive traits in compacted soil

MAIN CONCLUSION

Soil compaction reduces root exploration in chickpea. We found genes related to root architectural traits in chickpea that can help understand and improve root growth in compacted soils. Soil compaction is a major concern for modern agriculture, as it constrains plant root growth, leading to reduced resource acquisition. Phenotypic variation for root system architecture (RSA) traits in compacted soils is present for various crops; however, studies on genetic associations with these traits are lacking. Therefore, we investigated RSA traits in different soil compaction levels and identified significant genomic associations in chickpea. We conducted a Genome-Wide Association Study (GWAS) of 210 chickpea accessions for 13 RSA traits under three bulk densities (BD) (1.1BD, 1.6BD, and 1.8BD). Soil compaction decreases root exploration by reducing 12 RSA traits, except average diameter (AD). Further, AD is negatively correlated with lateral root traits, and this correlation increases in 1.8BD, suggesting the negative effect of AD on lateral root traits. Interestingly, we identified probable candidate genes such as GLP3 and LRX for lateral root traits and CRF1-like for total length (TL) in 1.6BD soil. In heavy soil compaction, DGK2 is associated with lateral root traits. Reduction in laterals during soil compaction is mainly due to delayed seedling establishment, thus making lateral root number a critical trait. Interestingly, we also found a higher contribution of the  GxE component of the number of root tips (Tips) to the total variation than the other lateral traits. We also identified a pectin esterase, PPE8B, associated with Tips in high soil compaction and a significantly associated SNP with the relative change in Tips depicting a trade-off between Tips and AD. Identified genes and loci would help develop soil-compaction-resistant chickpea varieties.

A citrate efflux transporter important for manganese distribution and phosphorus uptake in rice

The plant citrate transporters, functional in mineral nutrient uptake and homeostasis, usually belong to the multidrug and toxic compound extrusion transporter family. We identified and functionally characterized a rice (Oryza sativa) citrate transporter, OsCT1, which differs from known plant citrate transporters and is structurally close to rice silicon transporters. Domain analysis depicted that OsCT1 carries a bacterial citrate-metal transporter domain, CitMHS. OsCT1 showed citrate efflux activity when expressed in Xenopus laevis oocytes and is localized to the cell plasma membrane. It is highly expressed in the shoot and reproductive tissues of rice, and its promoter activity was visible in cells surrounding the vasculature. The OsCT1 knockout (KO) lines showed a reduced citrate content in the shoots and the root exudates, whereas overexpression (OE) line showed higher citrate exudation from their roots. Further, the KO and OE lines showed variations in the manganese (Mn) distribution leading to changes in their agronomical traits. Under deficient conditions (Mn-sufficient conditions followed by 8 days of 0 μm MnCl2  · 4H2 O treatment), the supply of manganese towards the newer leaf was found to be obstructed in the KO line. There were no significant differences in phosphorus (P) distribution; however, P uptake was reduced in the KO and increased in OE lines at the vegetative stage. Further, experiments in Xenopus oocytes revealed that OsCT1 could efflux citrate with Mn. In this way, we provide insights into a mechanism of citrate-metal transport in plants and its role in mineral homeostasis, which remains conserved with their bacterial counterparts.

MEDIATOR SUBUNIT17 is required for transcriptional optimization of root system architecture in Arabidopsis

Sucrose and auxin are well-known determinants of root system architecture (RSA). However, the factors that connect the signaling pathways evoked by these two critical factors during root development are poorly understood. In this study, we report the role of MEDIATOR SUBUNIT17 (MED17) in RSA and its involvement in the transcriptional integration of sugar and auxin signaling pathways in Arabidopsis (Arabidopsis thaliana). Sucrose regulates root meristem activation through the TARGET OF RAPAMYCIN-E2 PROMOTER BINDING FACTOR A (TOR-E2FA) pathway, and auxin regulates lateral root (LR) development through AUXIN RESPONSE FACTOR-LATERAL ORGAN BOUNDARIES DOMAIN (ARF-LBDs). Both sucrose and auxin play a vital role during primary and LR development. However, there is no clarity on how sucrose is involved in the ARF-dependent regulation of auxin-responsive genes. This study establishes MED17 as a nodal point to connect sucrose and auxin signaling. Transcription of MED17 was induced by sucrose in an E2FA/B-dependent manner. Moreover, E2FA/B interacted with MED17, which can aid in the recruitment of the Mediator complex on the target promoters. Interestingly, E2FA/B and MED17 also occupied the promoter of ARF7, but not ARF19, leading to ARF7 expression, which then activates auxin signaling and thus initiates LR development. MED17 also activated cell division in the root meristem by occupying the promoters of cell-cycle genes, thus regulating their transcription. Thus, MED17 plays an important role in relaying the transcriptional signal from sucrose to auxin-responsive and cell-cycle genes to regulate primary and lateral root development, highlighting the role of the Mediator as the transcriptional processor for optimal root system architecture in Arabidopsis.

Root-Expressed Rice PAP3b Enhances Secreted APase Activity and Helps Utilize Organic Phosphate

Phosphate (Pi) deficiency leads to the induction of purple acid phosphatases (PAPs) in plants, which dephosphorylate organic phosphorus (P) complexes in the rhizosphere and intracellular compartments to release Pi. In this study, we demonstrate that OsPAP3b belongs to group III low-molecular weight PAP and is low Pi-responsive, preferentially in roots. The expression of OsPAP3b is negatively regulated with Pi resupply. Interestingly, OsPAP3b was found to be dual localized to the nucleus and secretome. Furthermore, OsPAP3b is transcriptionally regulated by OsPHR2 as substantiated by DNA-protein binding assay. Through in vitro biochemical assays, we further demonstrate that OsPAP3b is a functional acid phosphatase (APase) with broad substrate specificity. The overexpression (OE) of OsPAP3b in rice led to increased secreted APase activity and improved mineralization of organic P sources, which resulted in better growth of transgenics compared to the wild type when grown on organic P as an exogenous P substrate. Under Pi deprivation, OsPAP3b knock-down and knock-out lines showed no significant changes in total P content and dry biomass. However, the expression of other phosphate starvation-induced genes and the levels of metabolites were found to be altered in the OE and knock-down lines. In addition, in vitro pull-down assay revealed multiple putative interacting proteins of OsPAP3b. Our data collectively suggest that OsPAP3b can aid in organic P utilization in rice. The APase isoform behavior and nuclear localization indicate its additional role, possibly in stress signaling. Considering its important roles, OsPAP3b could be a potential target for improving low Pi adaptation in rice.

Plant phosphate status influences root biotic interactions

Phosphorus (P) deficiency stress in combination with biotic stress(es) severely impacts crop yield. Plant responses to P deficiency overlapping with that of other stresses exhibit a high degree of complexity involving different signaling pathways. On the one hand, plants engage with rhizosphere microbiome/arbuscular mycorrhizal fungi for improved phosphate (Pi) acquisition and plant stress response upon Pi deficiency; on the other hand, this association is gets disturbed under Pi sufficiency. This nutrient-dependent response is highly regulated by the phosphate starvation response (PSR) mediated by the master regulator, PHR1, and its homolog, PHL. It is interesting to note that Pi status (deficiency/sufficiency) has a varying response (positive/negative) to different biotic encounters (beneficial microbes/opportunistic pathogens/insect herbivory) through a coupled PSR-PHR1 immune system. This also involves crosstalk among multiple players including transcription factors, defense hormones, miRNAs, and Pi transporters, among others influencing the plant-biotic-phosphate interactions. We provide a comprehensive view of these key players involved in maintaining a delicate balance between Pi homeostasis and plant immunity. Finally, we propose strategies to utilize this information to improve crop resilience to Pi deficiency in combination with biotic stresses.

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.

Root hair-specific transcriptome reveals response to low phosphorus in Cicer arietinum

Root hairs (RH) are a single-cell extension of root epidermal cells. In low phosphorus (LP) availability, RH length and density increase thus expanding the total root surface area for phosphate (Pi) acquisition. However, details on genes involved in RH development and response to LP are missing in an agronomically important leguminous crop, chickpea. To elucidate this response in chickpea, we performed tissue-specific RNA-sequencing and analyzed the transcriptome modulation for RH and root without RH (Root-RH) under LP. Root hair initiation and cellular differentiation genes like RSL TFs and ROPGEFs are upregulated in Root-RH, explaining denser, and ectopic RH in LP. In RH, genes involved in tip growth processes and phytohormonal biosynthesis like cell wall synthesis and loosening (cellulose synthase A catalytic subunit, CaEXPA2, CaGRP2, and CaXTH2), cytoskeleton/vesicle transport, and ethylene biosynthesis are upregulated. Besides RH development, genes involved in LP responses like lipid and/or pectin P remobilization and acid phosphatases are induced in these tissues summarizing a complete molecular response to LP. Further, RH displayed preferential enrichment of processes involved in symbiotic interactions, which provide an additional benefit during LP. In conclusion, RH shows a multi-faceted response that starts with molecular changes for epidermal cell differentiation and RH initiation in Root-RH and later induction of tip growth and various LP responses in elongated RH.

Bi-maxillary Protrusion: An Orthodontic Management

Bi-maxillary protrusion is a condition with protrusive and proclined upper and lower incisors and the patient is not able to close lips without strain. The presented case reported with the chief complaint of forwardly placed teeth, with skeletal class II malocclusion, and Angle's class I malocclusion with protrusive and forwardly placed upper and lower incisors. The treatment was performed with the extraction of all first premolars and retraction under absolute anchorage. The retraction of upper and lower lips of about 3 mm and 3.5 mm was achieved respectively and the patient was able to close lips without strain. With proper anchorage preparation, bi-maxillary protrusion can be successfully managed orthodontically.

Monogalactosyl diacylglycerol synthase 3 affects phosphate utilization and acquisition in rice

Galactolipids are essential to compensate for the loss of phospholipids by 'membrane lipid remodelling' in plants under phosphorus (P) deficiency conditions. Monogalactosyl diacylglycerol (MGDG) synthases catalyse the synthesis of MGDG which is further converted into digalactosyl diacylglycerol (DGDG), later replacing phospholipids in the extraplastidial membranes. However, the roles of these enzymes are not well explored in rice. In this study, the rice MGDG synthase 3 gene (OsMGD3) was identified and functionally characterized. We showed that the plant phosphate (Pi) status and the transcription factor PHOSPHATE STARVATION RESPONSE 2 (OsPHR2) are involved in the transcriptional regulation of OsMGD3. CRISPR/Cas9 knockout and overexpression lines of OsMGD3 were generated to explore its potential role in rice adaptation to Pi deficiency. Compared with the wild type, OsMGD3 knockout lines displayed a reduced Pi acquisition and utilization while overexpression lines showed an enhancement of the same. Further, OsMGD3 showed a predominant role in roots, altering lateral root growth. Our comprehensive lipidomic analysis revealed a role of OsMGD3 in membrane lipid remodelling, in addition to a role in regulating diacylglycerol and phosphatidic acid contents that affected the expression of Pi transporters. Our study highlights the role of OsMGD3 in affecting both internal P utilization and P acquisition in rice.

Soil carbon sequestration by root exudates

Root exudates are well-known 'labile' sources of soil carbon that can prime microbial activity. Recent investigations suggest that the stability of labile carbon inputs in soil mostly depends upon the physical, chemical, and biological properties of the surroundings. Here, we propose that, in some ecosystems, such as forests and grasslands, root exudates can function as a source of soil organic carbon (SOC) that can be stabilized through various mechanisms leading to long-term sequestration. Increasing soil carbon sequestration is important for capturing atmospheric CO₂ and combating climate change issues. Thus, there is an urgent need to preserve existing ecosystems and to adopt strategies such as afforestation, reforestation, and establishment of artificial grasslands to foster carbon sequestration through higher root exudate inputs in the soil.

OsJAZ11 regulates spikelet and seed development in rice

Seed size is one of the major determinants of seed weight and eventually, crop yield. As the global population is increasing beyond the capacity of current food production, enhancing seed size is a key target for crop breeders. Despite the identification of several genes and QTLs, current understanding about the molecular regulation of seed size/weight remains fragmentary. In the present study, we report novel role of a jasmonic acid (JA) signaling repressor, OsJAZ11 controlling rice seed width and weight. Transgenic rice lines overexpressing OsJAZ11 exhibited up to a 14% increase in seed width and ~30% increase in seed weight compared to wild type (WT). Constitutive expression of OsJAZ11 dramatically influenced spikelet morphogenesis leading to extra glume-like structures, open hull, and abnormal numbers of floral organs. Furthermore, overexpression lines accumulated higher JA levels in spikelets and developing seeds. Expression studies uncovered altered expression of JA biosynthesis/signaling and MADS box genes in overexpression lines compared to WT. Yeast two-hybrid and pull-down assays revealed that OsJAZ11 interacts with OsMADS29 and OsMADS68. Remarkably, expression of OsGW7, a key negative regulator of grain size, was significantly reduced in overexpression lines. We propose that OsJAZ11 participates in the regulation of seed size and spikelet development by coordinating the expression of JA-related, OsGW7 and MADS genes.

One-year safety and effectiveness of insulin degludec in patients with diabetes mellitus in routine clinical practice in India—TRUST (Tresiba real-world use study)

Objective

This post-authorization safety study (PASS) was conducted to evaluate the long-term safety and effectiveness of insulin degludec in patients with diabetes mellitus (DM) requiring insulin therapy in routine clinical practice in India.

Methods

Data on glycated hemoglobin (HbA1c) and adverse events (AEs) were collected up to 12 months after insulin degludec initiation.

Results

A total of 1057 adult patients with DM were enrolled, including 60.07% males with the mean duration of 22.2 ± 21.90 years with type 1 DM and 10.1 ± 7.37 years with type 2 DM and the mean HbA1c of 9.6 ± 1.9%. Insulin degludec was prescribed to improve HbA1c and fasting plasma glucose (FPG). Insulin degludec daily dose was increased from 14.8 ± 8.0 U to 18.0 ± 9.46 U over 12 months resulting in a significant decrease of HbA1c by 1.8 ± 1.68% compared with baseline. There were 84 events of confirmed hypoglycemia in 51 patients during the 12-month follow-up period, and 44 AEs were reported in 2.6% of patients, of which 2 AEs were serious and unrelated to the drug.

Conclusion

Insulin degludec is well tolerated in patients with DM. It improves glycemic control with reduced HbA1c, FPG, and postprandial glucose, with a low risk of hypoglycemia.

Significance of root hairs in developing stress-resilient plants for sustainable crop production

Root hairs represent a beneficial agronomic trait to potentially reduce fertilizer and irrigation inputs. Over the past decades, research in the plant model Arabidopsis thaliana has provided insights into root hair development, the underlying genetic framework and the integration of environmental cues within this framework. Recent years have seen a paradigm shift, where studies are now highlighting conservation and diversification of root hair developmental programs in other plant species and the agronomic relevance of root hairs in a wider ecological context. In this review, we specifically discuss the molecular evolution of the RSL (RHD Six-Like) pathway that controls root hair development and growth in land plants. We also discuss how root hairs contribute to plant performance as an active physiological rooting structure by performing resource acquisition, providing anchorage and constructing the rhizosphere with desirable physical, chemical and biological properties. Finally, we outline future research directions that can help achieve the potential of root hairs in developing sustainable agroecosystems.

Purple acid phosphatases: roles in phosphate utilization and new emerging functions

Plants strive for phosphorus (P), which is an essential mineral for their life. Since P availability is limiting in most of the world's soils, plants have evolved with a complex network of genes and their regulatory mechanisms to cope with soil P deficiency. Among them, purple acid phosphatases (PAPs) are predominantly associated with P remobilization within the plant and acquisition from the soil by hydrolyzing organic P compounds. P in such compounds remains otherwise unavailable to plants for assimilation. PAPs are ubiquitous in plants, and similar enzymes exist in bacteria, fungi, mammals, and unicellular eukaryotes, but having some differences in their catalytic center. In the recent past, PAPs' roles have been extended to multiple plant processes like flowering, seed development, senescence, carbon metabolism, response to biotic and abiotic stresses, signaling, and root development. While new functions have been assigned to PAPs, the underlying mechanisms remained understood poorly. Here, we review the known functions of PAPs, the regulatory mechanisms, and their relevance in crop improvement for P-use-efficiency. We then discuss the mechanisms behind their functions and propose areas worthy of future research. Finally, we argue that PAPs could be a potential target for improving P utilization in crops. In turn, this is essential for sustainable agriculture.

Specific galactolipids species correlate with rice genotypic variability for phosphate utilization efficiency

Membrane lipid remodeling helps in the efficient utilization of phosphorus (P) by replacing phospholipids with galactolipids during P deficiency. Previous studies have shown lipid remodeling in rice under P deficiency; however, main lipid classes did not show association with superior P-use-efficiency in rice genotypes. Here, diverse rice genotypes were extensively phenotyped in normal (NP) and low P (LP) conditions. Based on the phenotypic response to P deficiency, genotypes were identified as tolerant and sensitive. Further, bulks were generated differing in their physiological P-use-efficiency (PPUE) during LP condition. Shoot lipidome profiling of genotypes was performed and used to correlate the abundance of various lipid classes and their constituent species with the PPUE of the genotypes. Lipid remodeling was observed as a P-starvation-induced response in all the genotypes. However, neither total galacto- and phospholipids nor the lipid classes correlated with PPUE during P deficiency. However, the difference in PPUE in the two bulks correlated with specific lipid species of galactolipids (DGDG, MGDG). Further, DGDG34:3 had the highest Mol% among the differentially accumulated lipid species between the two bulks. Our study reveals the importance of specific galactolipids species in rice adaptation to P deficient soils and thus opens new targets for future research.

OsJAZ11 regulates phosphate starvation responses in rice

OsJAZ11 regulates phosphate homeostasis by suppressing jasmonic acid signaling and biosynthesis in rice roots. Jasmonic Acid (JA) is a key plant signaling molecule which negatively regulates growth processes including root elongation. JAZ (JASMONATE ZIM-DOMAIN) proteins function as transcriptional repressors of JA signaling. Therefore, targeting JA signaling by deploying JAZ repressors may enhance root length in crops. In this study, we overexpressed JAZ repressor OsJAZ11 in rice to alleviate the root growth inhibitory action of JA. OsJAZ11 is a low phosphate (Pi) responsive gene which is transcriptionally regulated by OsPHR2. We report that OsJAZ11 overexpression promoted primary and seminal root elongation which enhanced Pi foraging. Expression studies revealed that overexpression of OsJAZ11 also reduced Pi starvation response (PSR) under Pi limiting conditions. Moreover, OsJAZ11 overexpression also suppressed JA signaling and biosynthesis as compared to wild type (WT). We further demonstrated that the C-terminal region of OsJAZ11 was crucial for stimulating root elongation in overexpression lines. Rice transgenics overexpressing truncated OsJAZ11ΔC transgene (i.e., missing C-terminal region) exhibited reduced root length and Pi uptake. Interestingly, OsJAZ11 also regulates Pi homeostasis via physical interaction with a key Pi sensing protein, OsSPX1. Our study highlights the functional connections between JA and Pi signaling and reveals JAZ repressors as a promising candidate for improving low Pi tolerance of elite rice genotypes.

Organic acids: versatile stress-response roles in plants

Organic acids (OAs) are central to cellular metabolism. Many plant stress responses involve the exudation of OAs at the root-soil interface, which can improve soil mineral acquisition and toxic metal tolerance. Because of their simple structure, the low-molecular-weight OAs are widely studied. We discuss the conventional roles of OAs, and some newly emerging roles in plant stress tolerance. OAs are more versatile in their role in plant stress tolerance and are more efficient chelating agents than other acids, such as amino acids. Root OA exudation is important in soil carbon sequestration. These functions are key processes in combating climate change and helping with more sustainable food production. We briefly review the mechanisms behind enhanced biosynthesis, secretion, and regulation of these activities under different stresses, and provide an outline of the transgenic approaches targeted towards the enhanced production and secretion of OAs. A recurring theme of OAs in plant biology is their role as 'acids' modifying pH, as 'chelators' binding metals, or as 'carbon sources' for microbes. We argue that these multiple functions are key factors for understanding these molecules' important roles in plant stress biology. Finally, we discuss how the functions of OAs in plant stress responses could be used, and identify the important unanswered questions.

OsJAZ9 is involved in water-deficit stress tolerance by regulating leaf width and stomatal density in rice

Drought stress poses a severe threat to grain yield in rice. Our previous report demonstrated the role of OsJAZ9 in potassium homeostasis by modulating Jasmonic Acid (JA) signalling. While both potassium (K) and JA are known to have an important role in drought stress response, JA's repressor, i.e., JAZs' role in drought stress, remains elusive. Here we report that OsJAZ9 plays a critical role in rice water-deficit stress tolerance via influencing JA and ABA signalling. Overexpression of OsJAZ9 led to the enhanced ABA and JA levels. Our data further revealed that exogenous JA application antagonises the ABA-mediated inhibition of seed germination. Further, OsJAZ9 overexpression reduces leaf width and stomata density, leading to lower leaf transpiration rates than WT. This reduced transpiration and higher K content as osmoticum improved the water-deficit stress tolerance in OsJAZ9 overexpression lines. On the contrary, OsJAZ9 RNAi lines displayed enhanced sensitivity towards water-deficit stress. Our data provide new insights on the role of JA signalling repressors in rice response to water-deficit stress.

Emerging Molecular Strategies for Improving Rice Drought Tolerance

Rice occupies a pre-eminent position as a food crop in the world. Its production, how- ever, entails up to 3000 liters of water per kilogram of grain produced. Such high demand makes rice prone to drought easily. Sustainable rice cultivation with limited water resources requires the deployment of a suitable strategy for better water use efficiency and improved drought tolerance. Several drought-related genes have been evaluated in rice for their mode of action in conferring drought tolerance. Manipulation of components of abscisic acid signal transduction, stomatal density, deposition of cuticular wax, and protein modification pathways are emerging as priority targets. Gene reprogramming by microRNAs is also being explored to achieve drought tolerance. Genetically dissected Quantitative Trait Loci (QTLs) and their constituent genes are being deployed to develop drought-tolerant rice varieties. Progressive research and challenges include a better understanding of crucial components of drought response and search for new targets and the deployment of improved varieties in the field.

Reference gene identification for gene expression analysis in rice under different metal stress

Real-time quantitative polymerase chain reaction (RT-qPCR) is the most common approach to quantify changes in gene expression. Appropriate internal reference genes are essential for normalization of data of RT-qPCR. In the present study, we identified suitable reference genes for analysis of gene expression in rice seedlings subjected to different heavy metal stresses such as deficiencies of iron and zinc and toxicities of cobalt, cadmium and nickel. First, from publically available RNA-Seq data we identified 10 candidate genes having stable expression. We also included commonly used house-keeping gene OsUBQ5 (Ubiquitin 5) in our analysis. Expression stability of all the 11 genes was determined by two independent tools, NormFinder and geNorm. Our results show that selected candidate reference genes have higher stability in their expression compared to that of OsUBQ5. Genes with locus ID LOC_Os03g16690, encoding an oxysterol-binding protein (OsOBP) and LOC_Os01g56580, encoding Casein Kinase_1a.3 (OsCK1a.3) were identified to be the most stably expressed reference genes under most of the conditions tested. Finally, the study reveals that it is better to use a specific reference gene for a specific heavy metal stress condition rather than using a common reference gene for multiple heavy metal stress conditions. The reference genes identified here would be very useful for gene expression studies under heavy metal stresses in rice.

OsJAZ9 overexpression modulates jasmonic acid biosynthesis and potassium deficiency responses in rice

Enhanced bioactive JA (JA-Ile) accumulation in OsJAZ9 overexpressing rice helps plants tolerate K deficiency. Potassium (K) represents up to 10% of the plant's total dry biomass, and its deficiency makes plants highly susceptible to both abiotic and biotic stresses. K shortage results in the inhibition of root and shoots growth, but the underlying mechanism of this response is unclear. Our RNA-Seq and qPCR analysis suggested leading roles for JA pathway genes under K deficiency in rice. Notably, K deficiency and JA application produced similar phenotypic and transcriptional responses. Here, we integrated molecular, physiological and morphological studies to analyze the role of OsJAZ9 in JA homeostasis and K deficiency responses. We raised OsJAZ9 over-expression, knockdown, transcriptional reporter, translational reporter and C-terminal deleted translational reporter lines in rice to establish the role of JA signaling in K ion homeostasis. JA profiling revealed significantly increased JA-Ile levels in OsJAZ9 OE lines under K deficiency. Furthermore, we established that OsJAZ9 overexpression and knockdown result in K deficiency tolerance and sensitivity, respectively, by modulating various K transporters and root system architecture. Our data provide evidence on the crucial roles of OsJAZ9 for improving K deficiency tolerance in rice by altering JA levels and JA responses.

Genome-wide association study for phosphate deficiency responsive root hair elongation in chickpea

Root hairs (RHs) are single-celled elongated epidermal cells and play a vital role in nutrient absorption, particularly for immobile minerals like phosphorus (P). As an adaptive response to P deficiency, an increase in RH length enhances root-soil contact and absorptive area for P absorption. Genetic variations have been reported for RH length and its response to P deficiency in plants. However, only a few association studies have been conducted to identify genes and genetic loci associated with RH length. Here, we screened desi chickpea accessions for RH length and its plasticity under P deficiency. Further, the genome-wide association study (GWAS) was conducted to identify the genetic loci associated with RH length in P deficient and sufficient conditions. Although high variability was observed in terms of RH length in diverse genotypes, majority of the accessions showed typical response of increase in RH length in low P. Genome-wide association mapping identified many SNPs with significant associations with RH length in P-sufficient and P-deficient conditions. A few candidate genes for RH length in P deficient (SIZ1-like and HAD superfamily protein) and sufficient (RSL2-like and SMAP1-like) conditions were identified which have known roles in RH development and P deficiency response or both. Highly associated loci and candidate genes identified in this study would be useful for genomic-assisted breeding to develop P-efficient chickpea.

Influence of learning-style preferences in academic performance in the subject of human anatomy: an institution-based study among preclinical medical students

Purpose: The present study was conducted to find the preferred mode of learning among first-year preclinical students and compare the preferred mode of learning with sex, faculty of students, and academic performance of the students using the VARK questionnaire. Methods: A cross-sectional study was done among 142 first-year Bachelor of Medicine-Bachelor of Surgery and Bachelor of Dental Surgery students from February to May 2018. Demographic data and various academic performance marks were recorded for each individual. VARK (visual, aural, read/write and kinesthetic) questionnaire version 7.8 was administered to calculate the score of each component. Mean VARK scores were calculated and each student classified by their preferred mode of learning. The preferred mode of learning was compared with sex, nationality, faculty of students, and academic performance using χ ², unpaired t-tests, and the Mann-Whitney U test. P<0.05 was taken as statistically significant for comparison. Results: A majority of the students (53.52%) were multimodal. The most common multimodal mode of preference was bimodal (26.06%), while the most common unimodal preference was kinesthetic (29.06%). Total V score, K score, and VARK score were higher among males, while A and R scores were higher among females. The K score (7.96±2.35 in males and 6.96±2.43 in females) differed significantly (P=0.019) between male and female subjects. More subjects with higher scores in the theory exam of anatomy were unimodal learners (53.8%) compared to multimodal learners (46.2%). Conclusion: From this study, it can be concluded that undergraduate students were diverse in their learning styles, but most were multimodal. Though learning styles were found to vary by sex, nationality, and academic performance, differences were not statistically significant.

A novel glycerophosphodiester phosphodiesterase improves phosphate deficiency tolerance in rice

Soil phosphate (Pi) deficiency is major constraint for rice cultivation worldwide. Cellular membranes account for one third of cellular organic phosphorus (P) in the form of phospholipids. Therefore, remobilization of Pi from membrane phospholipids under Pi deficiency can be an important strategy to improve phosphorus use efficiency. Glycerophosphodiester phosphodiesterases (GDPDs) hydrolyse intermediate product of phospholipid catabolism, glycerophosphodiesters to glycerol-3-phosphate, a precursor for P and non P-lipid biosynthesis. Here, we show that OsGDPD2 is a Pi deficiency responsive gene, which is transcriptionally regulated by OsPHR2. In silico analysis of active site residues and enzymatic assays confirmed phosphodiesterase activity of OsGDPD2. All overexpression lines showed higher GDPD activity, Pi content, root growth, and biomass accumulation as compared with wild type. Conversely, silencing of OsGDPD2 led to decreased GDPD activity and Pi content. Notably, most of the P-containing metabolites and fatty acids were elevated in transgenic lines. Further, quantitative analysis of polar lipids revealed higher accumulation of several classes of phospholipids and galactolipids in overexpression lines indicating a potential role of OsGDPD2 in de novo glycerolipid biosynthesis. Thus, present study provides insights into novel physiological roles of OsGDPD2 in low Pi acclimation in rice.

Differential expression of salt-responsive genes to salinity stress in salt-tolerant and salt-sensitive rice (Oryza sativa L.) at seedling stage

The understanding of physio-biochemical and molecular attributes along with morphological traits contributing to the salinity tolerance is important for developing salt-tolerant rice (Oryza sativa L.) varieties. To explore these facts, rice genotypes CSR10 and MI48 with contrasting salt tolerance were characterized under salt stress (control, 75 and 150 mM NaCl) conditions. CSR10 expressed higher rate of physio-biochemical parameters, maintained lower Na/K ratio in shoots, and restricted Na translocation from roots to shoots than MI48. The higher expression of genes related to the osmotic module (DREB2A and LEA3) and ionic module (HKT2;1 and SOS1) in roots of CSR10 suppresses the stress, enhances electrolyte leakage, promotes the higher compatible solute accumulation, and maintains cellular ionic homeostasis leading to better salt stress tolerance than MI48. This study further adds on the importance of these genes in salt tolerance by comparing their behaviour in contrasting rice genotypes and utilizing specific marker to identify salinity-tolerant accessions/donors among germplasm; overexpression of these genes which accelerate the selection procedure precisely has been shown.

CRISPR-Cas9 based plant genome editing: Significance, opportunities and recent advances

Precise genome editing is a quantum leap in the field of plant sciences. Clustered regularly interspaced short palindromic repeats (CRISPR) and its associated Cas9 protein have emerged as a powerful tool for precise genome editing. CRISPR-Cas9 system introduces small heritable mutations (indels) in the genome of an organism. This system also enables precise gene characterization in plants with complex genomes. Besides, it offers new opportunities of trait stacking, where addition of desirable traits or removal of undesirable traits can be achieved simultaneously in a single event. With CRISPR-Cas9 RNPs technology, raising transgene free genetically modified plants is within realm of possibility which would be helpful in addressing regulatory concerns of transgenic plants. Several new advancements have been made in this technology which has extended its applications in almost every aspect of plant science. For example, recently developed catalytically inactive dCas9 fused with transcriptional effector domains allows targeted activation or silencing of the gene of interest. Apart from this, dCas9 fused with fluorescent labels is a budding tool in chromatin imaging studies. In this review, we summarize these recent advancements in CRISPR/Cas system and methods for analyzing the induced mutations, and its implementations in crop improvement.

Rice actin binding protein RMD controls crown root angle in response to external phosphate

Root angle has a major impact on acquisition of nutrients like phosphate that accumulate in topsoil and in many species; low phosphate induces shallower root growth as an adaptive response. Identifying genes and mechanisms controlling root angle is therefore of paramount importance to plant breeding. Here we show that the actin-binding protein Rice Morphology Determinant (RMD) controls root growth angle by linking actin filaments and gravity-sensing organelles termed statoliths. RMD is upregulated in response to low external phosphate and mutants lacking of RMD have steeper crown root growth angles that are unresponsive to phosphate levels. RMD protein localizes to the surface of statoliths, and rmd mutants exhibit faster gravitropic response owing to more rapid statoliths movement. We conclude that adaptive changes to root angle in response to external phosphate availability are RMD dependent, providing a potential target for breeders.

Author Correction: Rice auxin influx carrier OsAUX1 facilitates root hair elongation in response to low external phosphate

The original version of this Article omitted the following from the Acknowledgements:'We also thank DBT-CREST BT/HRD/03/01/2002.'This has been corrected in both the PDF and HTML versions of the Article.

Rice auxin influx carrier OsAUX1 facilitates root hair elongation in response to low external phosphate

Root traits such as root angle and hair length influence resource acquisition particularly for immobile nutrients like phosphorus (P). Here, we attempted to modify root angle in rice by disrupting the OsAUX1 auxin influx transporter gene in an effort to improve rice P acquisition efficiency. We show by X-ray microCT imaging that root angle is altered in the osaux1 mutant, causing preferential foraging in the top soil where P normally accumulates, yet surprisingly, P acquisition efficiency does not improve. Through closer investigation, we reveal that OsAUX1 also promotes root hair elongation in response to P limitation. Reporter studies reveal that auxin response increases in the root hair zone in low P environments. We demonstrate that OsAUX1 functions to mobilize auxin from the root apex to the differentiation zone where this signal promotes hair elongation when roots encounter low external P. We conclude that auxin and OsAUX1 play key roles in promoting root foraging for P in rice.

Plant root architecture can adapt to different nutrient conditions in the soil. Here Giri et al. show that the rice auxin influx carrier AUX1 mobilizes auxin from the root apex to the differentiation zone and promotes root hair elongation when roots encounter low external phosphate.

A mechanistic framework for auxin dependent Arabidopsis root hair elongation to low external phosphate

Phosphate (P) is an essential macronutrient for plant growth. Roots employ adaptive mechanisms to forage for P in soil. Root hair elongation is particularly important since P is immobile. Here we report that auxin plays a critical role promoting root hair growth in Arabidopsis in response to low external P. Mutants disrupting auxin synthesis (taa1) and transport (aux1) attenuate the low P root hair response. Conversely, targeting AUX1 expression in lateral root cap and epidermal cells rescues this low P response in aux1. Hence auxin transport from the root apex to differentiation zone promotes auxin-dependent hair response to low P. Low external P results in induction of root hair expressed auxin-inducible transcription factors ARF19, RSL2, and RSL4. Mutants lacking these genes disrupt the low P root hair response. We conclude auxin synthesis, transport and response pathway components play critical roles regulating this low P root adaptive response.

Regulatory feedback response mechanisms to phosphate starvation in rice

Phosphorus is a growth-limiting nutrient for plants. The growing scarcity of phosphate stocks threatens global food security. Phosphate-uptake regulation is so complex and incompletely known that attempts to improve phosphorus use efficiency have had extremely limited success. This study improves our understanding of the molecular mechanisms underlying phosphate uptake by investigating the transcriptional dynamics of two regulators: the Ubiquitin ligase PHO2 and the long non-coding RNA IPS1. Temporal measurements of RNA levels have been integrated into mechanistic mathematical models using advanced statistical techniques. Models based solely on current knowledge could not adequately explain the temporal expression profiles. Further modeling and bioinformatics analysis have led to the prediction of three regulatory features: the PHO2 protein mediates the degradation of its own transcriptional activator to maintain constant PHO2 mRNA levels; the binding affinity of the transcriptional activator of PHO2 is impaired by a phosphate-sensitive transcriptional repressor/inhibitor; and the extremely high levels of IPS1 and its rapid disappearance upon Pi re-supply are best explained by Pi-sensitive RNA protection. This work offers both new opportunities for plant phosphate research that will be essential for informing the development of phosphate efficient crop varieties, and a foundation for the development of models integrating phosphate with other stress responses.

Food security is a global priority. One aspect of this is the ability to grow crops in poorer soils with less fertilizer input, of which phosphate is both essential and resource limited. This study provides a quantitative understanding of the genetic regulation of phosphate uptake in rice upon its deficiency. The mathematical models developed in this article lead to three hypotheses for the gaps identified in current knowledge. One of these hypotheses has previously only been reported in animals while the other prompted laboratory experiments, revealing an extra level of regulation at short timescales. These models provide the basis for crop systems biologists to study other aspects of phosphate regulation, including its internal utilisation, external availability and foraging, and, more crucially, in response to other stresses.

Identification of Purple Acid Phosphatases in Chickpea and Potential Roles of CaPAP7 in Seed Phytate Accumulation

Purple acid phosphatases (PAPs) play important roles in phosphate (Pi) acquisition and utilization. These PAPs hydrolyze organic Phosphorus (P) containing compounds in rhizosphere as well as inside the plant cell. However, roles of PAPs in one of the most widely cultivated legumes, chickpea (Cicer arietnum L.), have not been unraveled so far. In the present study, we identified 25 putative PAPs in chickpea (CaPAPs) which possess functional PAP motifs and domains. Differential regulation of CaPAPs under different nutrient deficiencies revealed their roles under multiple nutrient stresses including Pi deficiency. Interestingly, most of the CaPAPs were prominently expressed in flowers and young pods indicating their roles in flower and seed development. Association mapping of SNPs underlying CaPAPs with seed traits revealed significant association of low Pi inducible CaPAP7 with seed weight and phytate content. Biochemical characterization of recombinant CaPAP7 established it to be a functional acid phosphatase with highest activity on most abundant organic-P substrate, phytate. Exogenous application of recombinant CaPAP7 enhanced biomass and Pi content of Arabidopsis seedlings supplemented with phytate as sole P source. Taken together, our results uncover the PAPs in chickpea and potential roles of CaPAP7 in seed phytate accumulation.

Improvement in phosphate acquisition and utilization by a secretory purple acid phosphatase (OsPAP21b) in rice

Phosphate (Pi) deficiency in soil system is a limiting factor for rice growth and yield. Majority of the soil phosphorus (P) is organic in nature, not readily available for root uptake. Low Pi-inducible purple acid phosphatases (PAPs) are hypothesized to enhance the availability of Pi in soil and cellular system. However, information on molecular and physiological roles of rice PAPs is very limited. Here, we demonstrate the role of a novel rice PAP, OsPAP21b in improving plant utilization of organic-P. OsPAP21b was found to be under the transcriptional control of OsPHR2 and strictly regulated by plant Pi status at both transcript and protein levels. Biochemically, OsPAP21b showed hydrolysis of several organophosphates at acidic pH and possessed sufficient thermostability befitting for high-temperature rice ecosystems with acidic soils. Interestingly, OsPAP21b was revealed to be a secretory PAP and encodes a distinguishable major APase (acid phosphatase) isoform under low Pi in roots. Further, OsPAP21b-overexpressing transgenics showed increased biomass, APase activity and P content in both hydroponics supplemented with organic-P sources and soil containing organic manure as sole P source. Additionally, overexpression lines depicted increased root length, biomass and lateral roots under low Pi while RNAi lines showed reduced root length and biomass as compared to WT. In the light of these evidences, present study strongly proposes OsPAP21b as a useful candidate for improving Pi acquisition and utilization in rice.

OsHAD1, a Haloacid Dehalogenase-Like APase, Enhances Phosphate Accumulation

Phosphorus (P) deficiency limits plant growth and yield. Since plants can absorb only the inorganic form of P (Pi), a large portion of soil P (organic and inorganic P complexes) remains unused. Here, we identified and characterized a PHR2-regulated, novel low-Pi-responsive haloacid dehalogenase (HAD)-like hydrolase, OsHAD1 While OsHAD1 is a functional HAD protein having both acid phosphatase and phytase activities, it showed little homology with other known low-Pi-responsive HAD superfamily members. Recombinant OsHAD1 is active at acidic pH and dephosphorylates a broad range of organic and inorganic P-containing substrates, including phosphorylated serine and sodium phytate. Exogenous application of recombinant OsHAD1 protein in growth medium supplemented with phytate led to marked increases in growth and total P content of Pi-deficient wild-type rice (Oryza sativa) seedlings. Furthermore, overexpression of OsHAD1 in rice resulted in enhanced phosphatase activity, biomass, and total and soluble P contents in Pi-deficient transgenic seedlings treated with phytate as a restricted Pi source. Gene expression and metabolite profiling revealed enhanced Pi starvation responses, such as up-regulation of multiple genes involved in Pi uptake and solubilization, accumulation of organic acids, enhanced secretory phosphatase activity, and depletion of ATP in overexpression lines as compared with the wild type. To elucidate the underlying regulatory mechanisms of OsHAD1, we performed in vitro pull-down assays, which revealed the association of OsHAD1 with protein kinases such as OsNDPKs. We conclude that, besides dephosphorylation of cellular organic P, OsHAD1 in coordination with kinases may regulate the phosphorylation status of downstream targets to accomplish Pi homeostasis under limited Pi supply.

Rice and chickpea GDPDs are preferentially influenced by low phosphate and CaGDPD1 encodes an active glycerophosphodiester phosphodiesterase enzyme

Rice and chickpea GDPD s are transcriptionally influenced by mineral deficiencies; especially, by phosphate starvation and CaGDP1 encodes an active glycerophosphodiester phosphodiesterase enzyme. Glycerophosphodiester phosphodiesterases (GDPDs) are enzymes involved in the degradation of glycerophosphodiesters into sn-glycerol-3-phosphate and corresponding alcohols. These phospholipid remodeling genes have been suggested to play important roles in phosphate homeostasis. However, comprehensive information about the role of GDPDs under low phosphate (P) and other nutrient deficiencies (N, K, Fe, Zn) in rice and chickpea is missing. Here, we identified 13 OsGDPDs and 6 CaGDPDs in rice and chickpea, respectively, and partly characterized their roles in multiple nutrient stresses. Expression profiling after 7 and 15 days of deficiency treatments revealed unique and overlapping differential expression patterns of OsGDPDs and CaGDPDs under different nutrient stresses. Principal component analysis on the expression patterns of OsGDPDs and CaGDPDs revealed their preferential role in P starvation. Some of the GDPDs were also induced by N, K, Fe and Zn deficiency in temporal manner in both crops suggesting their roles in multiple nutrient stresses. Biochemical characterization of highly responsive chickpea GDPD, CaGDPD1, confirmed its in vitro GDPD activity and revealed its optimal temperature, pH and cofactor requirements. Further, CaGDPD1 showed its accumulation in ER and endomembranes. We hereby propose CaGDPD1 and various OsGDPDs as low P responsive marker genes in chickpea and rice, respectively. Our data uphold role of GDPDs in multinutrient responses and suggest them as candidates for rice and chickpea improvement for tolerance to various nutrient deficiencies.

Rice Stress Associated Protein 1 (OsSAP1) Interacts with Aminotransferase (OsAMTR1) and Pathogenesis-Related 1a Protein (OsSCP) and Regulates Abiotic Stress Responses

Stress associated proteins (SAPs) are the A20/AN1 zinc-finger containing proteins which can regulate the stress signaling in plants. The rice SAP protein, OsSAP1 has been shown to confer abiotic stress tolerance to plants, when overexpressed, by modulating the expression of endogenous stress-related genes. To further understand the mechanism of OsSAP1-mediated stress signaling, OsSAP1 interacting proteins were identified using yeast two-hybrid analysis. Two novel proteins, aminotransferase (OsAMTR1) and a SCP/TAPS or pathogenesis-related 1 class of protein (OsSCP) were found to interact with OsSAP1. The genes encoding OsAMTR1 and OsSCP were stress-responsive and showed higher expression upon abiotic stress treatments. The role of OsAMTR1 and OsSCP under stress was analyzed by overexpressing them constitutively in Arabidopsis and responses of transgenic plants were assessed under salt and water-deficit stress. The OsAMTR1 and OsSCP overexpressing plants showed higher seed germination, root growth and fresh weight than wild-type plants under stress conditions. Overexpression of OsAMTR1 and OsSCP affected the expression of many known stress-responsive genes which were not affected by the overexpression of OsSAP1. Moreover, the transcript levels of OsSCP and OsAMTR1 were also unaffected by the overexpression of OsSAP1. Hence, it was concluded that OsSAP1 regulates the stress responsive signaling by interacting with these proteins which further regulate the downstream stress responsive gene expression.

Genome-wide DNA polymorphisms in low Phosphate tolerant and sensitive rice genotypes

Soil Phosphorus (P) deficiency is one of the major challenges to rice crop world-wide. Modern rice genotypes are highly P-responsive and rely on high input of P fertilizers. However, low P tolerant traditional cultivars and landraces have genetic potential to sustain well under low P. Identification of high resolution DNA polymorphisms (SNPs and InDels) in such contrasting genotypes is largely missing for low P response at gene levels. Here, we report high quality DNA polymorphisms in low P sensitive genotype, PB1 and tolerant traditional genotype, Dular. We performed whole genome resequencing using Illumina NGS platform and identified a total of 5,157,939 sequence variants in PB1 and Dular with reference to Nipponbare genome. We have identified approximately 2.3 million and 2.9 million high quality polymorphisms in PB1 and Dular, respectively, with an average read depth of ≥24X. We further mapped several DNA polymorphisms (non-synonymous and regulatory variants) having potential functional significance to key Phosphate Starvation Responsive (PSR) and root architecture genes in Dular and Kasalath using a compiled list of low P responsive genes. These identified variants can serve as a useful source of genetic variability for improving low P tolerance and root architecture of high yielding modern genotypes.

Rice OsiSAP7 negatively regulates ABA stress signalling and imparts sensitivity to water-deficit stress in Arabidopsis

Stress associated protein (SAP) genes in plants regulate abiotic stress responses. SAP gene family consists of 18 members in rice. Although their abiotic stress responsiveness is well established, the mechanism of their action is poorly understood. OsiSAP7 was chosen to investigate the mechanism of its action based on the dual nature of its sub-cellular localization preferentially in the nucleus or sub-nuclear speckles upon transient expression in onion epidermal cells. Its expression was down-regulated in rice seedlings under abiotic stresses. OsiSAP7 was localized evenly in the nucleus under unstressed conditions and in sub-nuclear speckles on MG132 treatment. OsiSAP7 exhibits E3 ubiquitin ligase activity in vitro. Abiotic stress responses of OsiSAP7 were assessed by its overexpression in Arabidopsis under the control of a stress inducible promoter rd29A. Stress response assessment was done at seed germination and advanced stages of development. Transgenics were ABA insensitive at seed germination stage and sensitive to water-deficit stress at advanced stage as compared to wild type (WT). They were also impaired in ABA and stress-responsive gene expression. Our study suggests that OsiSAP7 acts as a negative regulator of ABA and water-deficit stress signalling by acting as an E3 ubiquitin ligase.

JAZ Repressors: Potential Involvement in Nutrients Deficiency Response in Rice and Chickpea

Jasmonates (JA) are well-known phytohormones which play important roles in plant development and defense against pathogens. Jasmonate ZIM domain (JAZ) proteins are plant-specific proteins and act as transcriptional repressors of JA-responsive genes. JA regulates both biotic and abiotic stress responses in plants; however, its role in nutrient deficiency responses is very elusive. Although, JA is well-known for root growth inhibition, little is known about behavior of JAZ genes in response to nutrient deficiencies, under which root architectural alteration is an important adaptation. Using protein sequence homology and a conserved-domains approach, here we identify 10 novel JAZ genes from the recently sequenced Chickpea genome, which is one of the most nutrient efficient crops. Both rice and chickpea JAZ genes express in tissue- and stimuli-specific manners. Many of which are preferentially expressed in root. Our analysis further showed differential expression of JAZ genes under macro (NPK) and micronutrients (Zn, Fe) deficiency in rice and chickpea roots. While both rice and chickpea JAZ genes showed a certain level of specificity toward type of nutrient deficiency, generally majority of them showed induction under K deficiency. Generally, JAZ genes showed an induction at early stages of stress and expression declined at later stages of macro-nutrient deficiency. Our results suggest that JAZ genes might play a role in early nutrient deficiency response both in monocot and dicot roots, and information generated here can be further used for understanding the possible roles of JA in root architectural alterations for nutrient deficiency adaptations.

Comparative Morphophysiological Analyses and Molecular Profiling Reveal Pi-Efficient Strategies of a Traditional Rice Genotype

Phosphate (Pi) deficiency severely affects crop yield. Modern high yielding rice genotypes are sensitive to Pi deficiency whereas traditional rice genotypes are naturally compatible with low Pi ecosystems. However, the underlying molecular mechanisms for low Pi tolerance in traditional genotypes remain largely elusive. To delineate the molecular mechanisms for low Pi tolerance, two contrasting rice genotypes, Dular (low Pi tolerant), and PB1 (low Pi sensitive), have been selected. Comparative morphophysiological, global transcriptome and lipidome analyses of root and shoot tissues of both genotypes grown under Pi deficient and sufficient conditions revealed potential low Pi tolerance mechanisms of the traditional genotype. Most of the genes associated with enhanced internal Pi utilization (phospholipid remobilization) and modulation of root system architecture (RSA) were highly induced in the traditional rice genotype, Dular. Higher reserves of phospholipids and greater accumulation of galactolipids under low Pi in Dular indicated it has more efficient Pi utilization. Furthermore, Dular also maintained greater root growth than PB1 under low Pi, resulting in larger root surface area due to increased lateral root density and root hair length. Genes involved in enhanced low Pi tolerance of the traditional genotype can be exploited to improve the low Pi tolerance of modern high yielding rice cultivars.

Rice SAPs are responsive to multiple biotic stresses and overexpression of OsSAP1, an A20/AN1 zinc-finger protein, enhances the basal resistance against pathogen infection in tobacco

Eukaryotic A20/AN1 zinc-finger proteins (ZFPs) play an important role in the regulation of immune and stress response. After elucidation of the role of first such protein, OsSAP1, in abiotic stress tolerance, 18 rice stress associated protein (SAP) genes have been shown to be regulated by multiple abiotic stresses. In the present study, expression pattern of all the 18 OsSAP genes have been analysed in response to different biotic stress simulators, in order to get insights into their possible involvement in biotic stress tolerance. Our results showed the upregulation of OsSAP1 and OsSAP11 by all biotic stress simulator treatments. Furthermore, the functional role of OsSAP1 in plant defence responses has been explored through overexpression in transgenic plants. Constitutive expression of OsSAP1 in transgenic tobacco resulted into enhanced disease resistance against virulent bacterial pathogen, together with the upregulation of known defence-related genes. Present investigation suggests that rice SAPs are responsive to multiple biotic stresses and OsSAP1 plays a key role in basal resistance against pathogen infection. This strongly supports the involvement of rice SAPs in cross-talk between biotic and abiotic stress signalling pathways, which makes them ideal candidate to design strategies for protecting crop plants against multiple stresses.

Clinical experience with insulin detemir, biphasic insulin aspart and insulin aspart in people with type 2 diabetes: Results from the Tamil Nadu cohort of the A1chieve study

BACKGROUND

The A1chieve, a multicentric (28 countries), 24-week, non-interventional study evaluated the safety and effectiveness of insulin detemir, biphasic insulin aspart and insulin aspart in people with T2DM (n = 66,726) in routine clinical care across four continents.

MATERIALS AND METHODS

Data was collected at baseline, at 12 weeks and at 24 weeks. This short communication presents the results for patients enrolled from Tamil Nadu, India.

RESULTS

A total of 2221 patients were enrolled in the study. Four different insulin analogue regimens were used in the study. Patients had started on or were switched to biphasic insulin aspart (n = 1707), insulin detemir (n = 270), insulin aspart (n = 85), basal insulin plus insulin aspart (n = 79) and other insulin combinations (n = 80). At baseline glycaemic control was poor for both insulin naïve (mean HbA1c: 9.2%) and insulin user (mean HbA1c: 9.2%) groups. After 24 weeks of treatment, both the groups showed improvement in HbA1c (insulin naïve: -1.7%, insulin users: -1.7%). SADRs including major hypoglycaemic events did not occur in any of the study patients.

CONCLUSION

Starting or switching to insulin analogues was associated with improvement in glycaemic control with a low rate of hypoglycaemia.

SAPs as novel regulators of abiotic stress response in plants

Stress associated proteins (SAPs), novel A20/AN1 zinc-finger domain-containing proteins, are fast emerging as potential candidates for biotechnological approaches in order to improve abiotic stress tolerance in plants - the ultimate aim of which is crop-yield protection. Until relatively recently, such proteins had only been identified in humans, where they had been shown to be key regulators of innate immunity. Their phylogenetic relationship and recruitment of diverse protein domains reflect an architectural and mechanistic diversity. Emerging evidence suggests that SAPs may act as ubiquitin ligase, redox sensor, and regulator of gene expression during stress. Here, we evaluate the new knowledge on SAPs with a view to understand their mechanism of action. Furthermore, we set an agenda for investigating hitherto unexplored roles of these proteins.

Nitric oxide is involved in stimulation of tumor growth

The immune system can inhibit or stimulate tumor growth. Peritoneal cells (PEG) from MM3 mammary tumor-bearing mice (TBM) displayed enhanced capacity to produce nitric oxide (NO) upon stimulation with LPS plus IFN-gamma, as compared to normal mice. The addition of L-Arginine (L-Arg) increased NO release by TBM-PEC but not by normal PEG; this increase could be reversed with N-G-nitro-L-arginine methyl ester (L-NAME). This inhibitor, given systemically, decreased MM3 tumor growth but not lung metastasis. Tumor retardation was associated with inhibition of angiogenesis induced by spleen cells. Conversely, L-Arg potentiated vascular response but not tumor growth. In conclusion, NO synthesis is up regulated in PEC during MM3 tumor progression sustaining tumor growth by mediating the angiogenic cascade.

Glycinebetaine and abiotic stress tolerance in plants

The accumulation of osmolytes like glycinebetaine (GB) in cell is known to protect organisms against abiotic stresses via osmoregulation or osmoprotection. Transgenic plants engineered to produce GB accumulate very low concentration of GB, which might not be sufficient for osmoregulation. Therefore, other roles of GB like cellular macromolecule protection and ROS detoxification have been suggested as mechanisms responsible for abiotic stress tolerance in transgenic plants. In addition, GB influences expression of several endogenous genes in transgenic plants. The new insights gained about the mechanism of stress tolerance in GB accumulating transgenic plants are discussed.