Differential Reprogramming of Defense Network in Capsicum annum L. Plants Against Colletotrichum truncatum Infection by Phyllospheric and Rhizospheric Trichoderma Strains

Journal of Plant Growth Regulation - Induction of defense response in host plants by the Trichoderma spp. has been attributed as one of the major mechanisms leading to inhibition of the pathogenic...     

NAGbinder: An approach for identifying N‐acetylglucosamine interacting residues of a protein from its primary sequence

N‐acetylglucosamine (NAG) belongs to the eight essential saccharides that are required to maintain the optimal health and precise functioning of systems ranging from bacteria to human. In the present study, we have developed a method, NAGbinder, which predicts the NAG‐interacting residues in a protein from its primary sequence information. We extracted 231 NAG‐interacting nonredundant protein chains from Protein Data Bank, where no two sequences share more than 40% sequence identity. All prediction models were trained, validated, and evaluated on these 231 protein chains. At first, prediction models were developed on balanced data consisting of 1,335 NAG‐interacting and noninteracting residues, using various window size. The model developed by implementing Random Forest using binary profiles as the main principle for identifying NAG‐interacting residue with window size 9, performed best among other models. It achieved highest Matthews Correlation Coefficient (MCC) of 0.31 and 0.25, and Area Under Receiver Operating Curve (AUROC) of 0.73 and 0.70 on training and validation data set, respectively. We also developed prediction models on realistic data set (1,335 NAG‐interacting and 47,198 noninteracting residues) using the same principle, where the model achieved MCC of 0.26 and 0.27, and AUROC of 0.70 and 0.71, on training and validation data set, respectively. The success of our method can be appraised by the fact that, if a sequence of 1,000 amino acids is analyzed with our approach, 10 residues will be predicted as NAG‐interacting, out of which five are correct. Best models were incorporated in the standalone version and in the webserver available at https://webs.iiitd.edu.in/raghava/nagbinder/     

AKR2A interacts with KCS1 to improve VLCFAs contents and chilling tolerance of Arabidopsis thaliana

Arabidopsis thaliana AKR2A plays an important role in plant responses to cold stress. However, its exact function in plant resistance to cold stress remains unclear. In the present study, we found that the contents of very long‐chain fatty acids (VLCFAs) in akr2a mutants were decreased, and the expression level of KCS1 was also reduced. Overexpression of KCS1 in the akr2a mutants could enhance VLCFAs contents and chilling tolerance. Yeast‐2‐hybrid and bimolecular fluorescence complementation (BIFC) results showed that the transmembrane motif of KCS1 interacts with the PEST motif of AKR2A both in vitro and in vivo. Overexpression of KCS1 in akr2a mutants rescued akr2a mutant phenotypes, including chilling sensitivity and a decrease of VLCFAs contents. Moreover, the transgenic plants co‐overexpressing AKR2A and KCS1 exhibited a greater chilling tolerance than the plants overexpressing AKR2A or KCS1 alone, as well as the wild‐type. AKR2A knockdown and kcs1 knockout mutants showed the worst performance under chilling conditions. These results indicate that AKR2A is involved in chilling tolerance via an interaction with KCS1 to affect VLCFA biosynthesis in Arabidopsis.     

Cross-genera amplification of Cajanus spp. specific SSR markers in Clitoria ternatea (L.) and their application in genetic diversity studies

Clitoria ternatea (L.) is a medicinal leguminous plant and is cultivated to cater the need of herbal industries and asthetic purposes. The unavailability of steady molecular marker impedes the genetic improvement of C. ternatea. In the present study, transferability of 98 pairs of Cajanus spp. specific SSR primers were assessed among 14 genotypes of C. ternatea, varied for their flower color, floral architecture and bio-metabolite (taraxerol and delphinidin) content, and out of them 43 had successfully amplified the fragments. Among them, 36 pairs of primers showed 100% transferability, whereas rest seven varied from 42.86 to 92.85% transferability. The transferable 43 pairs of SSR primers generated 196 alleles across the 14 genotypes and the AMOVA analysis showed moderate genetic variation (55.1%) among the genotypes of C. ternatea, which was also reinforced by Nei’s genetic distance and gene identity estimates derived haplotype matrix. Similarly, both the principal coordinate analysis and dendrogram grouped these 14 genotypes of C. ternatea into two major clusters based on SSR allele distribution and frequency, and the clustering pattern is in accordance with petal color but in contrast to floral architecture. MCheza based outlier analysis revealed 16 alleles for balancing selection, which are putatively involved in the maintenance of genetic polymorphism in C. ternatea. Moreover, the estimates of molecular diversity and bio-metabolite content revealed the possible use of these genotypes in future breeding programme of this species.Electronic supplementary materialThe online version of this article (10.1007/s12298-020-00907-x) contains supplementary material, which is available to authorized users.     

Microwave initiated synthesis of polymethylmethacrylate grafted guar (GG-g-PMMA), characterizations and applications

Guar gum was grafted with polymethylmethacrylate (PMMA) by microwave initiated method. The synthesis was optimized for highest percentage grafting, by varying the microwave irradiation time and monomer (methyl methacrylate) concentration. The various grades of grafted product (GG-g-PMMA) were characterized through standard physicochemical characterization techniques (intrinsic viscosity measurement, elemental analysis, FTIR spectroscopy & SEM morphology study). Further, flocculation efficacy of this grafted polysaccharide was studied by standard 'Jar test' procedure in 0.5% kaolin suspension, to assess its application as flocculating agent for wastewater treatment and mineral ore beneficiation. Correlation between percentage grafting and intrinsic viscosity was also studied for the possibility of using it as a tool to control the intrinsic viscosity in the final product. This leads to the possibility of application of the grafted product as superior viscosifier than guar gum.     

Structural insight into the role of the human melanocortin 3 receptor cysteine residues on receptor function

Melanocortin-3 receptor (MC3R), expressed in the hypothalamus and limbic systems of the brain, as well as by peripheral sites, plays an important role in the regulation of energy homeostasis and other physiological functions. Past work shows that MC3R-deficiency resulted in fat mass increase, feeding efficiency increase, hyperleptinemia and mild hyperinsulinemia in mice and human. MC3R belongs to G-protein coupled receptor (GPCR) family and many studies indicate that some cysteine residues in GPCR play key roles in maintaining receptor tertiary structure and function. In this study, we examined the role of cysteine residues in MC3R on receptor function. Human MC3R (hMC3R) has eighteen cysteine residues where they are located in the extracellular loops (ELs), the transmembrane domains (TMs) and the intracellular loops (ILs). We replaced these cysteines with serine and expressed these receptors in HEK-293 cells which lack endogenous MC3R. Our results indicate that five cysteines in eighteen of the hMC3R are important for hMC3R function. Mutations, C305S, C311S, and C313S in EL3, resulted in significant decrease in receptor expression and receptor function while two other mutations C115S and C162S in TM3 significantly decreased NDP-MSH binding affinity and potency. These results suggest that extracellular cysteine residue 305, 311 and 313 are crucial for receptor expression and the transmembrane cysteine residue, C115 and 162 are important for ligand binding and signaling. These findings provide important insights into the importance of cysteine residues of hMC3R on receptor tertiary structure and function.