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Abstract Background Sustainable crop production along with best nutrient use efficiency is the key indicator of smart agriculture. Foliar application of plant nutrients can complement soil fertilization with improved nutrient uptake, translocation and utilization. Recent developments in slow releasing, nano-fertilizers in agriculture, begins a new era for sustainable use and management of natural resources. This study aims to explore the effectiveness of nano-nitrogen usage on plant growth, yield attributes and sustaining rice production while optimizing fertilizer N application through conventional (prilled urea) and nano-N source under salt stress conditions. Results The strategic substitutions of traditional urea by nano-nitrogen was distributed from partial to complete with 33, 50, 66 and 100% applications. Further, the strategic substitutions were compared in saline (ECe ∼ 6.0 dSm− 1) and sodic stress (pH ∼ 9.1) conditions along with normal soils to dissect the beneficial response of nano-N in two rice varieties (CSR 30 and PB 1121). Salt stress affected the plant performance by decreasing leaf relative water content upto 10%, total chlorophyll content by 1.3–1.5%, leaf area upto 29.9%, gas exchange attributes by 10–39%, with concomitant yield reductions upto ∼ 4%. Collateral improvement in leaf greenness (SPAD index) crop growth rate and net assimilation rate was observed with foliar application of Nano-N. 0.2–1.64% enhancement in growth traits, 0.93–1.85% in physiological traits, and comparable yield gains with 100% recommended dose of prilled were comparative with nano-substitutions. Salt tolerant rice variety, CSR-30 performed better than PB 1121 with better expression of morphological, physiological and yield traits under stress conditions and nitrogen substitutions. Conclusions Overall, our experimental findings revealed agricultural use of nano-N in improving the plant physiological efficiency and optimizing rice yields with partial N substitution through nano fertilizers under salt stress conditions. These studies are further open for futuristic aspects of long term effects of nano-fertilizers on soil nutrient depletion in correlation to yield enhancement in salt affected soils.

The simultaneous occurrence of biotic and abiotic stresses affects the performance of the crops in salt–affected agroecologies. The plant–microbe interaction with effective rhizobacteria can effectively manage these stresses. This study characterized the biocontrol, plant growth promotion, and responsiveness of rhizobacteria in wheat under salt-affected soils. Out of the 184 rhizobacteria isolates, the 20 isolates showed 41–72% growth inhibition of fungal phytopathogens of seedling blight of wheat (Fusarium sp), head blight of wheat (Fusarium oxysporum), onion molds (Penicillium sp and Aspergillus sp), root rot of wheat (Rhizoctonia solani), ear rot of corn (Aspergillus sp.) and spot blotch of wheat (Bipolaris sorokininana). The potent three rhizobacterial isolates identified as close neighbours of Bacillus amyloliquefaciens strain TA124, B. subtilis strain SB67 and B. subtilis strain BJ171 caused 65.5–71.1% growth inhibition of B. sorokiniana. The extracellular organic acid, siderophore, and chitinase enzymes played a significant role in rhizobacterial performance for fungal growth inhibition; and P and Zn solubilization in growth media. The foliar spray of bioformulation aids 15–20% reduction in the B. sorokiniana disease severity. The rhizobacterial responsiveness to the dual inoculation through seed treatment and foliar spray was 12.6–51, 15.8–46.3, and 13.2–148.1% for grain yield, P uptake, and disease suppression, respectively. The changes caused by rhizobacterial bioformulation in soil (Olsen's–P and microbial biomass carbon) and plant (proline, malondialdehyde, peroxidase, and Na+/K+ratio) explained 85% variability in the yield, P nutrition, and disease severity. Therefore, native rhizobacteria with biocontrol and plant growth-promoting capabilities can be an effective option for managing multiple stresses of crops in salt–affected agroecologies.

The antioxidant potential of halophytes, Dichanthium annulatum and Urochondra setulosa, was examined under the influence of high salinity. These halophytes were grown in lysimeters filled with saline soil and further irrigated with saline water to maintain different salt levels of ECe 30, 40 and 50 dS m−1 along with the one set in normal field soil without saline irrigation serving as control. The leaf samples were collected after saline irrigation and analyzed for the antioxidative enzymes i.e., Catalase (CAT), Peroxidase (POX), Superoxide dismutase (SOD), Ascorbate peroxidase (APX), Monodehydroascorbate reductase (MDHAR), Dehydroascorbate reductase (DHAR) and Glutathione reductase (GR), including the ROS metabolites such as H2O2 content, malondialdehyde content (MDA), ascorbic acid content and total glutathione content. The mechanism of scavenging the reactive oxygen species in both the halophytes was characterized.

Soil salinity is becoming a growing issue nowadays, severely affecting the world’s most productive agricultural landscapes. With intersecting and competitive challenges of shrinking agricultural lands and increasing demand for food, there is an emerging need to build resilience for adaptation to anticipated climate change and land degradation. This necessitates the deep decoding of a gene pool of crop plant wild relatives which can be accomplished through salt-tolerant species, such as halophytes, in order to reveal the underlying regulatory mechanisms. Halophytes are generally defined as plants able to survive and complete their life cycle in highly saline environments of at least 200-500 mM of salt solution. The primary criterion for identifying salt-tolerant grasses (STGs) includes the presence of salt glands on the leaf surface and the Na+ exclusion mechanism since the interaction and replacement of Na+ and K+ greatly determines the survivability of STGs in saline environments. During the last decades or so, various salt-tolerant grasses/halophytes have been explored for the mining of salt-tolerant genes and testing their efficacy to improve the limit of salt tolerance in crop plants. Still, the utility of halophytes is limited due to the non-availability of any model halophytic plant system as well as the lack of complete genomic information. To date, although Arabidopsis (Arabidopsis thaliana) and salt cress (Thellungiella halophila) are being used as model plants in most salt tolerance studies, these plants are short-lived and can tolerate salinity for a shorter duration only. Thus, identifying the unique genes for salt tolerance pathways in halophytes and their introgression in a related cereal genome for better tolerance to salinity is the need of the hour. Modern technologies including RNA sequencing and genome-wide mapping along with advanced bioinformatics programs have advanced the decoding of the whole genetic information of plants and the development of probable algorithms to correlate stress tolerance limit and yield potential. Hence, this article has been compiled to explore the naturally occurring halophytes as potential model plant species for abiotic stress tolerance and to further breed crop plants to enhance salt tolerance through genomic and molecular tools.

Pea (Pisum sativum L.) is moderately tolerant to salinity, early vegetative stage being more sensitive to salinity. In view of this, twenty pea genotypes collected from IIVR, Varanasi were screened for salt tolerance in terms of physiological and biochemical traits. The experiment was conducted in randomized complete block design in pots filled with soil (EC 20.47 dS/m) in 3 replications. Osmotic stress was created with irrigation water of salinity ECiw6 and 9 dS m-1 alongwith best available water (BAW) having ECiw 0.6 dS m-1 (control). It was found that mean photosynthetic rate (Pn)decreased with increasing levels of salinity in all the genotypes except VRPMR-11 (12.6%), VRP-5 (16.18%) and VRP-22 (16.5%) at ECiw9 dSm-1.The chlorophyll content was also significantly higher in VRPE-25, VRP-5 and VRPE-100 over all the treatments. Fv/Fm values reduced by 12.9% at ECiw6 dSm-1 and 24.19% at ECiw9 dSm-1. The best indicator of stress, proline accumulated many folds with increasing levels of salinity, i.e. approximately 8 folds proline content at ECiw6 dSm-1 and 13 folds proline content at ECiw9 dSm-1 was observed. The membrane damage in terms of lipid peroxidation was measured as MDA content and accumulated significantly at higher saline level followed by ECiw 6 dSm-1 and least in control. Leaf K+/Na+ ratio decreased significantly with increasing stress level. Among the genotypes, significantly higher K+/Na+ was observed in VRP-22, whereas minimum in VRP-343 and VRPE-25. More than 80 % reduction in yield was observed in pea genotypes VRP-6, VRPE-100, BB-29(b)-14 green, VRP-233, PC-531, VRP-12-1 and VRP-7, whereas the minimum reduction was obtained in VRPE-101 (39.1%), VRP-343 (43.2%), Pusa Pragati (43.8%), VRP-22 (45.8%), and VRPE-25 (48.37%) at ECiw9 dS m-1. Thus on the basis of the physiological and biochemical expressions of tolerance, these genotypes were characterized as sensitive, moderately tolerant or tolerant to salinity.

The screening of 114 groundnut (Arachis hypogaea L.) genotypes (61 advanced breeding lines and 53 released cultivars) was undertaken in the screening plots to identify the iron-efficient genotypes tolerant to lime-induced ironchlorosis. The crop was grown and the intensity of chlorosis of top five leaves was rated for visual chlorotic rating (VCR) score on a 1-5 scale and the percentage of plants showing deficiency symptoms at 10, 20, 30 and 65 days after emergence during the cropping season. The tolerant genotypes had shown significantly lower VCR, higher Soil Plant Analysis Development (SPAD) chlorophyll meter reading and chlorophyll values, active Fe, and high yield compared to the sensitive ones. The correlation of visual chlorosis range with SPAD, chlorophyll and available iron content along with the mineral nutrients like, Fe, Zn, Mn, K, and P clearly identified the groundnut genotypes as tolerant, moderately tolerant and sensitive to iron chlorosis. Based on various parameters, out of 114 genotypes, 22 were grouped as tolerant, 48 moderately tolerant, 32 normal and 12 sensitive. Maximum variability was obtained in groundnut genotypes for Fe and fodder weight.

Pearl millet is a staple food for more than 90 million people residing in highly vulnerable hot arid and semi–arid regions of Africa and Asia. These regions are more prone to detrimental effects of soil salinity on crop performance in terms of reduced biomass and crop yields. We investigated the physiological mechanisms of salt tolerance to irrigation induced salinity stress (ECiw ~3, 6 & 9 dSm–1) and their confounding effects on plant growth and yield in pearl millet inbred lines and hybrids. On average, nearly 30% reduction in above ground plant biomass was observed at ECiw ~6 dSm-1 which stretched to 56% at ECiw ~9 dSm-1 in comparison to best available water. With increasing salinity stress, the crop performance of test hybrids was better in comparison to inbred lines; exhibiting relatively higher stomatal conductance (gS; 16%), accumulated lower proline (Pro; –12%) and shoot Na+/K+(–31%), synthesized more protein (SP; 2%) and sugars (TSS; 32%) compensating in lower biomass (AGB; –22%) and grain yield (GY: –14%) reductions at highest salinity stress of ECiw ~9 dSm–1. Physiological traits modeling underpinning plant salt tolerance and adaptation mechanism illustrated the key role of 7 traits (AGB, Pro, SS, gS, SPAD, Pn, and SP) in hybrids and 8 traits (AGB, Pro, PH, Na+, K+, Na+/K+, SPAD, and gS) in inbred lines towards anticipated grain yield variations in salinity stressed pearl millet. Most importantly, the AGB alone, explained >91% of yield variation among evaluated hybrids and inbreed lines at ECiw ~9 dSm–1. Cumulatively, the better morpho–physiological adaptation and lesser yield reduction with increasing salinity stress in pearl millet hybrids (HHB 146, HHB 272, and HHB 234) and inbred lines (H77/833–2–202, ICMA 94555 and ICMA 843–22) substantially complemented in increased plant salt tolerance and yield stability over a broad range of salinity stress. The information generated herein will help address in deciphering the trait associated physiological alterations to irrigation induced salt stress, and developing potential hybrids in pearl millet using these parents with special characteristics.

An experiment was conducted in microplots at ICAR-Central Soil Salinity Research Institute, Karnal, Haryana during 2013–16 to study the adaptive response of Salvadora oleoides, a facultative halophyte under saline, sodic and mixed saline-sodic conditions. S. oleoides was not able to survive at higher sodicity (pH ~ 10.0) and salinity (ECe ~ 35 dS/m) as well as on the mixed sodicity and salinity levels (pH ~ 9.0 along with ECe ~ 10, 15, 20 dS/m). Stress either salinity or sodicity brought reduction in plant height, chlorophyll content and gas exchange attributes, but S. oleoides maintained gaseous exchange at moderate stress level. S. oleoides accumulated 4 fold higher proline under sodic stress and 6 fold under salinity stress. Other osmolytes, TSS and soluble protein decreased with stress intensification to maintain osmotic balance. In comparison to control, sodicity enhanced Na+ and Cl- by 54.57% and 20.33%, while under salinity, Na+ was enhanced by 141.52–256.09% and Cl- by 47.83–115.58% at ECe ~ 15 and 25 dS/m, respectively. Inspite of such higher increase in Na+ and Cl-, S. oleoides retained good amount of mean K+ (1.22%) in leaf tissue. S. oleoides also maintained leaf Na+/K+ below 1.0 under stress condition of pH ~ 9.5 and ECe ~ 15 dS/m. Based on the studied physio-biochemical analysis, Salvadora oleoides exhibited good adaptive potential under moderate salinity and sodicity stress and could be used as a promising salt-tolerant plant species for plantation in salt affected areas.

Present study was carried out to assess the effects of soil salinity/sodicity on mineral nutrient status of Urochondra setulosa, Leptochloa fusca and Sporobolus marginatus at ICAR- Central Soil Salinity Research Institute, Karnal, Haryana during 2016–19. Treatments of salinity/sodicity (pH ~ 9.5, pH ~ 10, ECe ~ 30 dS/m, ECe ~ 40 dS/m and ECe ~ 50 dS/m) were created in microplots (2.5 m × 1.5 m × 0.5 m) using saline/sodic water. Na+ and Cl– content (% DW) significantly increased with increasing sodicity/salinity stress condition in all three grass halophytes, whereas K+ content decreased. These grass halophytic species showed relatively less reduction in Ca, Mg and Fe contents up to sodic stress of pH ~ 9.5 and salinity level of ECe ~ 40 dS/m. Zn, Cu and Mn content decreased with increasing stress conditions but higher decrease was observed under sodic stress. The Na+/K+ and Na+/Ca2+ ratio was considered as indicators for measuring salt tolerance in plants. Na+/K+ ratio increased with increasing stress condition in all the three grasses but Leptachloa maintained their Na+/K+ near pH 1.0 under sodic stress condition and also maintained their Na+/Ca2+ below 1.0 up to pH ~ 9.5 and ECe ~ 40 dS/m. Higher sodic stress of pH~10.0 caused significant increase in Na+/Ca2+ in Urochondra and Sporobolus, whereas under highest salinity level, Leptachloa showed highest value for Na+/Ca2+. Changes in the accumulation patterns of nutrient in response to salinity is an important aspect and study showed highest positive correlation between Ca - Mg & Zn and negative between Na - Ca and K.

Abstract Soil salinity is one of the major limiting factors for crop productivity across the world. Halophytes have recently been a source of attraction for exploring the survival and tolerance mechanisms at extreme saline conditions. Urochondra setulosa is one of the obligate grass halophyte that can survive in up to 1000 mM NaCl. The de novo transcriptome of Urochondra leaves at different salt concentrations of 300–500 mM NaCl was generated on Illumina HiSeq. Approximately 352.78 million high quality reads with an average contig length of 1259 bp were assembled de novo. A total of 120,231 unigenes were identified. On an average, 65% unigenes were functionally annotated to known proteins. Approximately 35% unigenes were specific to Urochondra. Differential expression revealed significant enrichment (P

Two halophytes, Dichanthium annulatum (moderately salt tolerant) and Urochondra setulosa (highly salt tolerant) were selected to generate transcriptome at different salinity levels. Sequencing of RNA samples was done on Illumina-Hi-Seq platform for de novo transcriptome assembly from the leaf tissues of D. annulatum at salinity of ECe ∼30 dS/m and of U. setulosa at three salt levels (i.e. ECe ∼30, ∼40 and ∼50 dS/m). DESeq was used for identification of differentially expressed transcripts and a total of 267,196 and 384,442 transcripts were assembled through Trinity in both the plants respectively. A total of 32,246 and 25,479 SSRs were identified respectively in both the plants using MISA perl script with mono and tri-nucleotide repeats as most common motif.

Mutations or genetic variation in noncoding regions of the genome harbouring cis-regulatory elements (CREs), or enhancers, have been widely implicated in human disease and disease risk. However, our ability to assay the impact of these DNA sequence changes on enhancer activity is currently very limited because of the need to assay these elements in an appropriate biological context. Here, we describe a method for simultaneous quantitative assessment of the spatial and temporal activity of wild-type and disease-associated mutant human CRE alleles using live imaging in zebrafish embryonic development. We generated transgenic lines harbouring a dual-CRE dual-reporter cassette in a pre-defined neutral docking site in the zebrafish genome. The activity of each CRE allele is reported via expression of a specific fluorescent reporter, allowing simultaneous visualisation of where and when in development the wild-type allele is active and how this activity is altered by mutation.

Pomegranate (Punica granatum L., family: Lytheraceae) is widely grown in arid and semi-arid areas across the globe, where moderate or relatively high salt concentration in the soil negatively affect the plant growth properties. However, there is scarce information on the response of pomegranate cultivars under saline field conditions. Therefore, this experiment was conducted in a saline field (soil ECe 6-8 dS/m, ECiw 3.9-4.2 dS/m) during two consecutive years (2017-18) at Nain Experimental Farm, Panipat, India to study the effects of salinity on vegetative growth and fruit quality traits in 15 genotypes of pomegranate. The experiment was laid out in Randomized Block Design with four replications. Analysis of Variance revealed highly significant differences among the genotypes for fruit growth and quality traits. Results showed considerable variation in the plant growth and fruit quality traits of the pomegranate genotypes. Our findings indicated that fruit quality traits like fruit weight, juice percentage, number of arils, and aril colour could be used as criteria for selecting promising pomegranate genotypes for salt-affected soils. Overall, genotypes Udaipur 2, Udaipur 3, Rajasmand 4 and Jaipur 1 seem to be more tolerant of salinity stress than other genotypes and thus have potential for cultivation in saline soils.

Salinity is increasingly becoming a significant problem for the most important yet intrinsically salt-sensitive grain legume chickpea. Chickpea is extremely sensitive to salinity during the reproductive phase. Therefore, it is essential to understand the molecular mechanisms by comparing the transcriptomic dynamics between the two contrasting genotypes in response to salt stress. Chickpea exhibits considerable genetic variation amongst improved cultivars, which show better yields in saline conditions but still need to be enhanced for sustainable crop production. Based on previous extensive multi-location physiological screening, two identified genotypes, JG11 (salt-tolerant) and ICCV2 (salt-sensitive), were subjected to salt stress to evaluate their phenological and transcriptional responses. RNA-Sequencing is a revolutionary tool that allows for comprehensive transcriptome profiling to identify genes and alleles associated with stress tolerance and sensitivity. After the first flowering, the whole flower from stress-tolerant and sensitive genotypes was collected. A total of ~300 million RNA-Seq reads were sequenced, resulting in 2022 differentially expressed genes (DEGs) in response to salt stress. Genes involved in flowering time such as FLOWERING LOCUS T (FT) and pollen development such as ABORTED MICROSPORES (AMS), rho-GTPase, and pollen-receptor kinase were significantly differentially regulated, suggesting their role in salt tolerance. In addition to this, we identify a suite of essential genes such as MYB proteins, MADS-box, and chloride ion channel genes, which are crucial regulators of transcriptional responses to salinity tolerance. The gene set enrichment analysis and functional annotation of these genes in flower development suggest that they can be potential candidates for chickpea crop improvement for salt tolerance.

Grafting on salt tolerant eggplant rootstocks can be a promising approach for enhancing the salinity tolerance of tomato. In this study, the performance of tomato cv. Kashi Aman grafted on two salt tolerant eggplant rootstocks (IC-111056 and IC-354557) was evaluated against non-grafted control under saline (ECiw 6 and 9 dS m−1) and non-saline (ECiw ~1 dS m−1) irrigation for 2 years. Grafting improved tomato plant performance under salt stress. Moreover, rootstock IC-111056 outperformed IC-354557. An increase in the average fruit yield of grafted plants compared with non-grafted control at 6 and 9 dS m−1 was 24.41% and 55.84%, respectively with rootstock IC-111056 and 20.25% and 49.08%, respectively with IC-354557. Grafted plants maintained a superior water status under saline irrigation, evidenced with the relative water content and chlorophyll SPAD index, along with higher proline and antioxidant enzyme activities (superoxide dismutase, catalase, and ascorbate peroxidase). Rootstocks mediated the partitioning of toxic saline ions in the scions by promoting higher Na+ accumulation (14% of mean accumulation) in the older leaves and lower (24%) in the younger leaves of grafted plants. This resulted in higher K+/Na+ ratios within the younger (active) leaves of the grafted plants. Our study demonstrates that grafting tomato seedlings on selected salt tolerant eggplant rootstocks is a viable alternative for improving plant physiological status and fruit yield under salt stress, through favorable modulation of salt ion partitioning in the scions.

An experiment was conducted on Urochondra setulosa (grass halophyte) to explore its survival mechanism under stress conditions. For this, different treatments of salinity/sodicity (pH ~ 9.5, pH ~ 10, ECe ~ 30 dS/m, ECe ~ 40 dS/m and ECe ~ 50 dS/m) were created in micro-plots. Roots are the primary structure that first senses the negative effects of salt stress. So, roots were selected to study the tolerance mechanism. Salinity stress caused higher Na+ accumulation and less reduction in K+ content in comparison to sodic stress. Roots accumulated 4.57 folds higher proline at ECe ~ 50 dS/m, whereas under pH ~ 10.0, 3.11 fold higher accumulations than the control roots were observed. Higher reduction in protein content was observed under sodicity stress than salinity stress. In control roots, a total of 26 polypeptide bands were expressed ranging from 12.43 kDa to 81.3 kDa. Under high salinity stress, number of polypeptide bands increased to 31 at ECe ~ 50 dS/m that might be responsible for their survival and growth while sodic stress led to disappearance of more number of polypeptides with a total number of 23 polypeptides at pH ~ 10.0. Interestingly, it was also found that sodic stress had higher damaging affect on Urochondra metabolism in comparison to salinity stress which makes it salinity tolerant grass.

The effects of maturity stage and harvesting season were investigated on fruit quality attributes like total antioxidant activity (DPPH), total flavanoids, total phenolics, H2O2 scavenging activity and ascorbic acid content in fruits of guava (Psidium guajava L) cv. Allahabad Safeda obtained from ICAR-CSSRI, Karnal guava orchard. Based on fruit colour and firmness, fruits representing four distinct maturity stages, i.e., immature, mature, ripe and overripe; and two crop seasons, i.e. summer and winter; were selected for biochemical analysis. Significant differences were observed in the antioxidant activities and chemical composition of the fruits at different maturity stages during summer and winter seasons of harvesting. Guava fruits collected in winter season showed higher antioxidant activity, flavanoids content, total phenolics, H2O2 scavenging activity and ascorbic acid content as compared with summer season fruits. Immature fruits had higher antioxidant activity, flavanoids content and total phenol content (49.35%, 26.98 mg/100g and 24.84 mg TA/g) during both the seasons than mature (40.02%, 24.22 mg/100g and 23.95 mg TA/g), ripe (31.76%, 20.54 mg/100g and 23.62 mg TA/g) and overripe fruits (25.7%, 17.04 mg/100g and 23.17 mg TA/g), respectively. In contrast, H2O2 scavenging activity increased with maturity in both the seasons and was found to be maximum in over ripe fruits (501.48 μmol/g). Ripe fruits had the highest ascorbic acid content (205.03 mg/100 g) that considerably decreased in over ripe fruits (137.25 mg/100 g). These findings indicated that both maturity stage and harvesting season significantly influenced fruit biochemical composition in guava cv. Allahabad Safeda. Season and maturity stage-specific variations in fruit quality assume significance from post-harvest management and consumer preference perspectives.

Determining aetiology of genetic disorders caused by damaging mutations in protein-coding genes is well established. However, understanding how mutations in the vast stretches of the noncoding genome contribute to genetic abnormalities remains a huge challenge. Cis-regulatory elements (CREs) or enhancers are an important class of noncoding elements. CREs function as the primary determinants of precise spatial and temporal regulation of their target genes during development by serving as docking sites for tissue-specific transcription factors. Although a large number of potential disease-associated CRE mutations are being identified in patients, lack of robust methods for mechanistically linking these mutations to disease phenotype is currently hampering the understanding of their roles in disease aetiology. Here, we have described the various systems available for testing the CRE potential of stretches of noncoding regions harbouring mutations implicated in human disease. We highlight advances in the field leading to the establishment of zebrafish as a powerful system for robust and cost-effective functional assays of CRE activity, enabling rapid identification of causal variants in regulatory regions and the validation of their role in disruption of appropriate gene expression.

Genetic variance was evaluated in one hundred sixty genotypes of garden pea (Pisum sativum L.) for nine morphological traits through multivariate analysis. Analysis of variance indicated that the genotypes varied significantly among themselves in respect of 9 characters studied. The genotypes were grouped into 14 clusters depending upon their morphological similarity through principal component analysis. Clustering pattern indicated that majority of genotypes, i.e. 113 (70%) were genetically close to each other and grouped in 3 clusters, while apparent diversity was mainly noticed due to 47 genotypes (30%) distributed over 11 clusters. The maximum inter-cluster distance was noticed between III and XIV (61.49) followed by III and VII (51.33) and III and XII (53.27). Considering cluster mean, the genotypes of cluster III might be selected as a suitable parent for future hybridization programme. The contribution of each character towards the expression of genetic divergence indicated that 10-pod weight contributed maximum (58.29) followed by days to 50% flowering (23.83), plant height (11.31) and shelling percent (4.95%). These four characters contributed more than 98% to the total genetic divergence in the genotypes studied.

BACKGROUND: Aggregation of unfolded proteins occurs mainly through the exposed hydrophobic surfaces. Any mechanism of inhibition of this aggregation should explain the prevention of these hydrophobic interactions. Though arginine is prevalently used as an aggregation suppressor, its mechanism of action is not clearly understood. We propose a mechanism based on the hydrophobic interactions of arginine. METHODOLOGY: We have analyzed arginine solution for its hydrotropic effect by pyrene solubility and the presence of hydrophobic environment by 1-anilino-8-naphthalene sulfonic acid fluorescence. Mass spectroscopic analyses show that arginine forms molecular clusters in the gas phase and the cluster composition is dependent on the solution conditions. Light scattering studies indicate that arginine exists as clusters in solution. In the presence of arginine, the reverse phase chromatographic elution profile of Alzheimer's amyloid beta 1-42 (Abeta(1-42)) peptide is modified. Changes in the hydrodynamic volume of Abeta(1-42) in the presence of arginine measured by size exclusion chromatography show that arginine binds to Abeta(1-42). Arginine increases the solubility of Abeta(1-42) peptide in aqueous medium. It decreases the aggregation of Abeta(1-42) as observed by atomic force microscopy. CONCLUSIONS: Based on our experimental results we propose that molecular clusters of arginine in aqueous solutions display a hydrophobic surface by the alignment of its three methylene groups. The hydrophobic surfaces present on the proteins interact with the hydrophobic surface presented by the arginine clusters. The masking of hydrophobic surface inhibits protein-protein aggregation. This mechanism is also responsible for the hydrotropic effect of arginine on various compounds. It is also explained why other amino acids fail to inhibit the protein aggregation.