Epigenetic malleability at core promoter initiates tobacco PR-1a expression post salicylic acid treatment.

BACKGROUND: Tobacco's PR-1a gene is induced by pathogen attack or exogenous application of salicylic acid (SA). Nucleosome mapping and chromatin immunoprecipitation assay were used to delineate the histone modifications on the PR-1a promoter. However, the epigenetic modifications of the inducible promoter of the PR-1a gene are not fully understood yet. METHODS AND RESULTS: Southern approach was used to scan the promoter of PR-1a to identify presence of nucleosomes, ChIP assays were performed using anti-histones antibodies of repressive chromatin by di- methylated at H3K9 and H4K20 or active chromatin by acetylated H3K9/14 and H4K16 to find epigenetic malleability of nucleosome over core promoter in uninduced or induced state post SA treatment. Class I and II mammalian histone deacetylase (HDAC) inhibitor TSA treatment was used to enhance the expression of PR-1a by facilitating the histone acetylation post SA treatment. Here, we report correlated consequences of the epigenetic modifications correspond to disassembly of the nucleosome (spans from - 102 to + 55 bp, masks TATA and transcription initiation) and repressor complex from core promoter, eventually initiates the transcription of PR-1a gene post SA treatment. While active chromatin marks di and trimethylation of H3K4, acetylation of H3K9 and H4K16 are increased which are associated to the transcription initiation of PR-1a following SA treatment. However, in uninduced state constitutive expression of a negative regulator (SNI1) of AtPR1, suppresses AtPR1 expression by six-fold in Arabidopsis thaliana. Further, we report 50-to-1000-fold increased expression of AtPR1 in uninduced lsd1 mutant plants, up to threefold increased expression of AtPR1 in uninduced histone acetyl transferases (HATs) mutant plants, SNI1 dependent negative regulation of AtPR1, all together our results suggest that inactive state of PR-1a is indeed maintained by a repressive complex. CONCLUSION: The study aimed to reveal the mechanism of transcription initiation of tobacco PR-1a gene in presence or absence of SA. This is the first study that reports nucleosome and repressor complex over core promoter region maintains the inactivation of gene in uninduced state, and upon induction disassembling of both initiates the downstream gene activation process.

Atmospheric temperature and humidity demonstrated strong correlation with productivity in tropical moist deciduous forests.

Tropical forests sequester six times higher carbon than that released by humans annually into the atmosphere. These biodiversity-rich tropical forests have high net primary productivity (NPP), which differs among constituent plant communities. Tropical moist deciduous forests occupy 179,335 km2 of India's geographical area and constitute 44% of the country's total protected area (PA) forests. The productivity of these forests has neither been estimated specifically nor precisely. We measured the annual NPP of three predominant distinct community types, viz., mixed (DM), sal (SM), and teak (TP), in a tropical moist deciduous forest in northern India. The NPP was estimated from tree biomass data collected from nine long-term ecological research (LTER) plots of 1 ha each representing the above three community types. The estimated annual NPP were 10.28, 6.25, and 9.79 Mg ha-1 year-1 in DM; 8.93, 7.09, and 10.59 Mg ha-1 year-1 in SM; and 14.57, 7.14, and 13.56 Mg ha-1 year-1 in TP for the years 2010, 2011, and 2012, respectively. The NPP was correlated with tree density, height and DBH, species richness, diversity, microclimatic and edaphic variables, and leaf area index (LAI) using principal component analysis (PCA) and generalized linear modeling (GLM). Air temperature and humidity were strongly related to NPP in all the community types, while "complementarity" and "selection effects" contributed to the NPP in both the sal and mixed forest communities with equal importance, and the NPP in teak plantation ould point to "dominance effect."

Senna leaf curl virus: a novel begomovirus identified in Senna occidentalis.

Begomoviruses are whitefly-transmitted, single-stranded DNA viruses that infect a variety of cultivated (crop) and non-cultivated (weed) plants. The present study identified a novel begomovirus and satellites (alpha- and betasatellite) in Senna occidentalis (syn. Cassia occidentalis) showing leaf curl symptoms. The begomovirus shared a maximum sequence identity of 88.6 % with french bean leaf curl virus (JQ866297), whereas the alphasatellite and the betasatellite shared identities of 98 % and 90 % with ageratum yellow vein India alphasatellite (LK054802) and papaya leaf curl betasatellite (HM143906), respectively. No other begomovirus or satellites were detected in the suspected plants. We propose to name the virus "senna leaf curl virus" (SenLCuV).

De novo assembly and characterization of transcriptomes of early-stage fruit from two genotypes of Annona squamosa L. with contrast in seed number.

BACKGROUND: Annona squamosa L., a popular fruit tree, is the most widely cultivated species of the genus Annona. The lack of transcriptomic and genomic information limits the scope of genome investigations in this important shrub. It bears aggregate fruits with numerous seeds. A few rare accessions with very few seeds have been reported for Annona. A massive pyrosequencing (Roche, 454 GS FLX+) of transcriptome from early stages of fruit development (0, 4, 8 and 12 days after pollination) was performed to produce expression datasets in two genotypes, Sitaphal and NMK-1, that show a contrast in the number of seeds set in fruits. The data reported here is the first source of genome-wide differential transcriptome sequence in two genotypes of A. squamosa, and identifies several candidate genes related to seed development. RESULTS: Approximately 1.9 million high-quality clean reads were obtained in the cDNA library from the developing fruits of both the genotypes, with an average length of about 568 bp. Quality-reads were assembled de novo into 2074 to 11004 contigs in the developing fruit samples at different stages of development. The contig sequence data of all the four stages of each genotype were combined into larger units resulting into 14921 (Sitaphal) and 14178 (NMK-1) unigenes, with a mean size of more than 1 Kb. Assembled unigenes were functionally annotated by querying against the protein sequences of five different public databases (NCBI non redundant, Prunus persica, Vitis vinifera, Fragaria vesca, and Amborella trichopoda), with an E-value cut-off of 10(-5). A total of 4588 (Sitaphal) and 2502 (NMK-1) unigenes did not match any known protein in the NR database. These sequences could be genes specific to Annona sp. or belong to untranslated regions. Several of the unigenes representing pathways related to primary and secondary metabolism, and seed and fruit development expressed at a higher level in Sitaphal, the densely seeded cultivar in comparison to the poorly seeded NMK-1. A total of 2629 (Sitaphal) and 3445 (NMK-1) Simple Sequence Repeat (SSR) motifs were identified respectively in the two genotypes. These could be potential candidates for transcript based microsatellite analysis in A. squamosa. CONCLUSION: The present work provides early-stage fruit specific transcriptome sequence resource for A. squamosa. This repository will serve as a useful resource for investigating the molecular mechanisms of fruit development, and improvement of fruit related traits in A. squamosa and related species.

Association of satellites with a mastrevirus in natural infection: complexity of Wheat dwarf India virus disease.

UNLABELLED: In contrast to begomoviruses, mastreviruses have not previously been shown to interact with satellites. This study reports the first identification of the association of satellites with a mastrevirus in field-grown plants. Two alphasatellite species were detected in different field samples of wheat infected with Wheat Dwarf India Virus (WDIV), a Cotton leaf curl Multan alphasatellite (CLCuMA) and a Guar leaf curl alphasatellite (GLCuA). In addition to the alphasatellites, a betasatellite, Ageratum yellow leaf curl betasatellite (AYLCB), was also identified in the wheat samples. No begomovirus was detected in the wheat samples, thus establishing association of the above-named satellites with WDIV. Agrobacterium-mediated inoculation of WDIV in wheat, in the presence of either of the alphasatellites or the betasatellite, resulted in infections inducing more severe symptoms. WDIV efficiently maintained each of the alphasatellites and the betasatellite in wheat. The satellites enhanced the level of WDIV DNA in wheat. Inoculation of the satellites isolated from wheat with various begomoviruses into Nicotiana tabacum demonstrated that these remain capable of interacting with the viruses with which they were first identified. Virus-specific small RNAs accumulated in wheat upon infection with WDIV but were lower in abundance in plants coinfected with the satellites, suggesting that both the alphasatellites and the betasatellite suppress RNA silencing. These results suggest that the selective advantage for the maintenance of the alphasatellites and the betasatellite by WDIV in the field is in overcoming RNA silencing-mediated host defense. IMPORTANCE: Wheat is the most widely cultivated cereal crop in the world. A number of viruses are important pathogens of wheat, including the viruses of the genus Mastrevirus, family Geminiviridae. This study reports the association of subgenomic components, called satellites (alpha- and betasatellites), with a mastrevirus, Wheat Dwarf India Virus (WDIV), isolated from two distant locations in India. This study reports the first identification of the satellites in a monocot plant. The satellites enhanced accumulation of WDIV and severity of disease symptoms. The satellites lowered the concentration of virus-specific small RNAs in wheat plants, indicating their silencing suppressor activity. The involvement of the satellites in symptom severity of the mastrevirus can have implications in the form of economic impact of the virus on crop yield. Understanding the role of the satellites in disease severity is important for developing disease management strategies.

Genome-wide transcriptome study in wheat identified candidate genes related to processing quality, majority of them showing interaction (quality x development) and having temporal and spatial distributions.

BACKGROUND: The cultivated bread wheat (Triticum aestivum L.) possesses unique flour quality, which can be processed into many end-use food products such as bread, pasta, chapatti (unleavened flat bread), biscuit, etc. The present wheat varieties require improvement in processing quality to meet the increasing demand of better quality food products. However, processing quality is very complex and controlled by many genes, which have not been completely explored. To identify the candidate genes whose expressions changed due to variation in processing quality and interaction (quality x development), genome-wide transcriptome studies were performed in two sets of diverse Indian wheat varieties differing for chapatti quality. It is also important to understand the temporal and spatial distributions of their expressions for designing tissue and growth specific functional genomics experiments. RESULTS: Gene-specific two-way ANOVA analysis of expression of about 55 K transcripts in two diverse sets of Indian wheat varieties for chapatti quality at three seed developmental stages identified 236 differentially expressed probe sets (10-fold). Out of 236, 110 probe sets were identified for chapatti quality. Many processing quality related key genes such as glutenin and gliadins, puroindolines, grain softness protein, alpha and beta amylases, proteases, were identified, and many other candidate genes related to cellular and molecular functions were also identified. The ANOVA analysis revealed that the expression of 56 of 110 probe sets was involved in interaction (quality x development). Majority of the probe sets showed differential expression at early stage of seed development i.e. temporal expression. Meta-analysis revealed that the majority of the genes expressed in one or a few growth stages indicating spatial distribution of their expressions. The differential expressions of a few candidate genes such as pre-alpha/beta-gliadin and gamma gliadin were validated by RT-PCR. Therefore, this study identified several quality related key genes including many other genes, their interactions (quality x development) and temporal and spatial distributions. CONCLUSIONS: The candidate genes identified for processing quality and information on temporal and spatial distributions of their expressions would be useful for designing wheat improvement programs for processing quality either by changing their expression or development of single nucleotide polymorphisms (SNPs) markers.

Spatial X-ray fluorescence micro-imaging of minerals in grain tissues of wheat and related genotypes.

MAIN CONCLUSION: Wheat and its related genotypes show distinct distribution patterns for mineral nutrients in maternal and filial tissues in grains. X-ray-based imaging techniques are very informative to identify genotypes with contrasting tissue-specific localization of different elements. This can help in the selection of suitable genotypes for nutritional improvement of food grain crops. Understanding mineral localization in cereal grains is important for their nutritional improvement. Spatial distribution of mineral nutrients (Mg, P, S, K, Ca, Fe, Zn, Mn and Cu) was investigated between and within the maternal and filial tissues in grains of two wheat cultivars (Triticum aestivum Cv. WH291 and WL711), a landrace (T. aestivum L. IITR26) and a related wild species Aegilops kotschyi, using micro-proton-induced X-ray emission (µ-PIXE) and micro-X-ray fluorescence (µ-XRF). Aleurone and scutellum were major storage tissues for macro (P, K, Ca and Mg) as well as micro (Fe, Zn, Cu and Mn) nutrients. Distinct elemental distribution patterns were observed in each of the four genotypes. A. kotschyi, the wild relative of wheat and the landrace, T. aestivum L. IITR26, accumulated more Zn and Fe in scutellum and aleurone than the cultivated wheat varieties, WH291 and WL711. The landrace IITR26, accumulated far more S in grains, Mn in scutellum, aleurone and embryo region, Ca and Cu in aleurone and scutellum, and Mg, K and P in scutellum than the other genotypes. Unlike wheat, lower Mn and higher Fe, Cu and Zn concentrations were noticed in the pigment strand of A. kotschyi. Multivariate statistical analysis, performed on mineral distribution in major grain tissues (aleurone, scutellum, endosperm and embryo region) resolved the four genotypes into distinct clusters.

ßC1 is a pathogenicity determinant: not only for begomoviruses but also for a mastrevirus.

ßC1 proteins, encoded by betasatellites, are known to be pathogenicity determinants, and they are responsible for symptom expression in many devastating diseases caused by begomoviruses. We report the involvement of ßC1 in pathogenicity determination of a mastrevirus. Analysis of field samples of wheat plants containing wheat dwarf India virus (WDIV) revealed the presence of a full-length and several defective betasatellite molecules. The detected betasatellite was identified as ageratum yellow leaf curl betasatellite (AYLCB). No begomovirus was detected in any of the samples. The full-length AYLCB contained an intact ßC1 gene, whereas the defective molecules contained complete or partial deletions of ßC1. Agroinoculation of wheat with the full-length AYLCB and WDIV or of tobacco with ageratum enation virus enhanced the pathogenicity and accumulation of the respective viruses, whereas the defective molecules could not. This study indicates that ßC1 is a pathogenicity determinant for WDIV and can interact functionally not only with begomoviruses but also with a mastrevirus.

Virus-induced gene silencing using a modified betasatellite: a potential candidate for functional genomics of crops.

Betasatellites are geminivirus-associated single-stranded DNA molecules that play an important role in symptom modulation. A VIGS vector was developed by modifying cotton leaf curl Multan betasatellite (CLCuMB). CLCuMB DNA was modified by replacing the ßC1 gene with a multiple cloning site. The silencing ability of the modified CLCuMB was investigated by cloning a fragment of a host gene (Su) or a reporter transgene (uidA) into the modified CLCuMB and co-agroinoculation with cotton leaf curl Multan virus, cotton leaf curl Kokhran virus, and ageratum enation virus, separately. The inoculated Nicotiana tabacum, N. benthamiana, Solanum lycopersicum, Arabidopsis thaliana and Gossypium hirsutum plants showed efficient silencing of the cognate genes.

Pattern of iron distribution in maternal and filial tissues in wheat grains with contrasting levels of iron.

Iron insufficiency is a worldwide problem in human diets. In cereals like wheat, the bran layer of the grains is an important source of iron. However, the dietary availability of iron in wheat flour is limited due to the loss of the iron-rich bran during milling and processing and the presence of anti-nutrients like phytic acid that keep iron strongly chelated in the grain. The present study investigated the localization of iron and phosphorus in grain tissues of wheat genotypes with contrasting grain iron content using synchrotron-based micro-X-ray fluorescence (micro-XRF) and micro-proton-induced X-ray emission (micro-PIXE). X-ray absorption near-edge spectroscopy (XANES) was employed to determine the proportion of divalent and trivalent forms of Fe in the grains. It revealed the abundance of oxygen, phosphorus, and sulphur in the local chemical environment of Fe in grains, as Fe-O-P-R and Fe-O-S-R coordination. Contrasting differences were noticed in tissue-specific relative localization of Fe, P, and S among the different genotypes, suggesting a possible effect of localization pattern on iron bioavailability. The current study reports the shift in iron distribution from maternal to filial tissues of grains during the evolution of wheat from its wild relatives to the present-day cultivated varieties, and thus suggests the value of detailed physical localization studies in varietal improvement programmes for food crops.

Detection and characterization of a new betasatellite: variation in disease symptoms of tomato leaf curl Pakistan virus-India due to associated betasatellite.

A begomovirus and its associated betasatellites were amplified and sequenced from tobacco plants affected with leaf curl disease. The begomovirus was identified as a new strain of tomato leaf curl Pakistan virus (ToLCPKV), which is referred to here as ToLCPKV-India. A previously known betasatellite [tomato leaf curl Patna betasatellite (ToLCPaB)] and a new betasatellite were also found in leaf-curl-affected samples. The use of infectious clones of ToLCPKV-IN plus ToLCPaB for agroinoculation led to typical leaf curl, while ToLCPKV-IN together with the new betasatellite resulted in curling and chlorosis of leaves. Based on these disease symptoms, we propose to name the new betasatellite tobacco leaf chlorosis betasatellite (TbLChB).

A new betasatellite associated with cotton leaf curl Burewala virus infecting tomato in India: influence on symptoms and viral accumulation.

A begomovirus and its associated alpha- and betasatellite were detected in tomato plants affected with leaf curl disease. Based on a nucleotide sequence identity of 99 %, this begomovirus was designated an isolate of cotton leaf curl Burewala virus (CLCuBuV). The alphasatellite exhibited 93 % sequence identity to cotton leaf curl Burewala alphasatellite (CLCuBuA) and is hence referred to here as a variant of CLCuBuA. The detected betasatellite was recombinant in nature and showed 70 % sequence identity to the known betasatellites. Inoculation of healthy tomato with CLCuBuV plus betasatellite, either in the presence or the absence of alphasatellite, led to typical leaf curling, while inoculation with CLCuBuV in the absence of betasatellite resulted in mild symptoms. This confirmed the role of the betasatellite in expression of disease symptoms. We propose to name the newly detected betasatellite tomato leaf curl Hajipur betasatellite (ToLCHJB).

Ellagic acid & gallic acid from Lagerstroemia speciosa L. inhibit HIV-1 infection through inhibition of HIV-1 protease & reverse transcriptase activity.

BACKGROUND & OBJECTIVES: Banaba (Lagerstroemia speciosa L.) extracts have been used as traditional medicines and are effective in controlling diabetes and obesity. The aim of this study was to evaluate the anti-HIV property of the extracts prepared from the leaves and stems of banaba, and further purification and characterization of the active components. METHODS: Aqueous and 50 per cent ethanolic extracts were prepared from leaves and stems of banaba and were evaluated for cytotoxicity and anti-HIV activity using in vitro reporter gene based assays. Further, three compounds were isolated from the 50 per cent ethanolic extract of banaba leaves using silica gel column chromatography and characterization done by HPLC, NMR and MS analysis. To delineate the mode of action of the active compounds, reverse transcriptase assay and protease assay were performed using commercially available kits. RESULTS: All the extracts showed a dose dependent inhibition of HIV-1-infection in TZM-bl and CEM-GFP cell lines with a maximum from the 50 per cent ethanolic extract from leaves (IC 50 = 1 to 25 µg/ml). This observation was confirmed by the virus load (p24) estimation in infected CEM-GFP cells when treated with the extracts. Gallic acid showed an inhibition in reverse transcriptase whereas ellagic acid inhibited the HIV-1 protease activity. INTERPRETATION & CONCLUSIONS: The present study shows a novel anti-HIV activity of banaba. The active components responsible for anti-HIV activity were gallic acid and ellagic acid, through inhibition of reverse transcriptase and HIV protease, respectively and hence could be regarded as promising candidates for the development of topical anti-HIV-1 agents.

CRISPR/Cas9-mediated editing of phytoene desaturase (PDS) gene in an important staple crop, potato.

The gene editing using the CRISPR/Cas9 system has become an important biotechnological tool for studying gene function and improving crops. In this study, we have used CRISPR/Cas9 system for editing the phytoene desaturase gene (PDS) in popular Indian potato cultivar Kufri Chipsona-I. A construct (pHSE401) carrying two target gRNAs with glycine tRNA processing system under the control of Arabidopsis U6 promoter and the Cas9 protein was constructed and transformed in potato plants using Agrobacterium-mediated genetic transformations. The regeneration efficiency of 45% was observed in regenerated plants, out of which 81% of the putative transformants shoot lines exhibited mutant or bleached phenotype (albinism). The deletion mutations were detected within the StPDS gene in the genotyped plants and a mutation efficiency of 72% for gRNA1 and gRNA2 has been detected using Sanger sequencing. Hence, we set up a CRISPR/Cas9-mediated genome editing protocol which is efficient and generates mutations (deletions) within StPDS gene in potato. The bleached phenotype is easily detectable after only few weeks after Agrobacterium-mediated transformation. This is the first report as a proof of concept for CRISPR/Cas9-based editing of PDS gene in Indian potato cv. Kufri Chipsona-I. This study demonstrates that CRISPR/Cas9 can be used to edit genes at high frequency within the genome of the potato for various traits. Therefore, this study will aid in creating important mutants for modifying molecular mechanisms controlling traits of agronomic importance.

Genome wide expression profiling of two accession of G. herbaceum L. in response to drought.

BACKGROUND: Genome-wide gene expression profiling and detailed physiological investigation were used for understanding the molecular mechanism and physiological response of Gossypium herbaceum, which governs the adaptability of plants in drought conditions. Recently, microarray-based gene expression analysis is commonly used to decipher genes and genetic networks controlling the traits of interest. However, the results of such an analysis are often plagued due to a limited number of genes (probe sets) on microarrays. On the other hand, pyrosequencing of a transcriptome has the potential to detect rare as well as a large number of transcripts in the samples quantitatively. We used Affymetrix microarray as well as Roche's GS-FLX transcriptome sequencing for a comparative analysis of cotton transcriptome in leaf tissues under drought conditions. RESULTS: Fourteen accessions of Gossypium herbaceum were subjected to mannitol stress for preliminary screening; two accessions, namely Vagad and RAHS-14, were selected as being the most tolerant and most sensitive to osmotic stress, respectively. Affymetrix cotton arrays containing 24,045 probe sets and Roche's GS-FLX transcriptome sequencing of leaf tissue were used to analyze the gene expression profiling of Vagad and RAHS-14 under drought conditions. The analysis of physiological measurements and gene expression profiling showed that Vagad has the inherent ability to sense drought at a much earlier stage and to respond to it in a much more efficient manner than does RAHS-14. Gene Ontology (GO) studies showed that the phenyl propanoid pathway, pigment biosynthesis, polyketide biosynthesis, and other secondary metabolite pathways were enriched in Vagad under control and drought conditions as compared with RAHS-14. Similarly, GO analysis of transcriptome sequencing showed that the GO terms responses to various abiotic stresses were significantly higher in Vagad. Among the classes of transcription factors (TFs) uniquely expressed in both accessions, RAHS-14 showed the expression of ERF and WRKY families. The unique expression of ERFs in response to drought conditions reveals that RAHS-14 responds to drought by inducing senescence. This was further supported by transcriptome analysis which revealed that RAHS-14 responds to drought by inducing many transcripts related to senescence and cell death. CONCLUSION: The comparative genome-wide gene expression profiling study of two accessions of G.herbaceum under drought stress deciphers the differential patterns of gene expression, including TFs and physiologically relevant processes. Our results indicate that drought tolerance observed in Vagad is not because of a single molecular reason but is rather due to several unique mechanisms which Vagad has developed as an adaptation strategy.

Development and characterization of genomic and expressed SSRs for levant cotton (Gossypium herbaceum L.).

Four microsatellite-enriched genomic libraries for CA(15), GA(15), AAG(8) and ATG(8) repeats and transcriptome sequences of five cDNA libraries of Gossypium herbaceum were explored to develop simple sequence repeat (SSR) markers. A total of 428 unique clones from repeat enriched genomic libraries were mined for 584 genomic SSRs (gSSRs). In addition, 99,780 unigenes from transcriptome sequencing were explored for 8,900 SSR containing sequences with 12,471 expressed SSRs. The present study adds 1,970 expressed SSRs and 263 gSSRs to the public domain for the use of genetic studies of cotton. When 150 gSSRs and 50 expressed SSRs were tested on a panel of four species of cotton, 68 gSSRs and 12 expressed SSRs revealed polymorphism. These 200 SSRs were further deployed on 15 genotypes of levant cotton for the genetic diversity assessment. This is the first report on the successful use of repeat enriched genomic library and expressed sequence database for microsatellite markers development in G. herbaceum.

A novel mastrevirus infecting wheat in India.

A new mastrevirus (family Geminivridae) infecting wheat in India was detected by rolling-circle amplification (RCA). The complete nucleotide sequence of the virus was determined to be 2783 bp long. Analysis of the nucleotide sequence revealed identity and a genome organisation typical of a mastrevirus. An identical virus was detected in the candidate insect vector (leafhopper) collected from the field. Agroinoculation of young wheat plants with an infectious clone of the virus resulted in dwarfing of plants, identical to what was observed in the field, confirming that this novel virus was the causative agent of the disease. Considering the low degree of sequence identity to any known mastrevirus, the virus described here is suggested to be a member of a new species. Based on symptoms, we propose the name "wheat dwarf India virus".

Sterol glycosyltransferases-identification of members of gene family and their role in stress in Withania somnifera.

Sterol glycosyltransferases (SGTs) catalyze the transfer of sugar molecules to diverse sterol molecules, leading to a change in their participation in cellular metabolism. Withania somnifera is a medicinal plant rich in sterols, sterol glycosides and steroidal lactones. Sterols and their modified counterparts are medicinally important and play a role in adaptation of the plant to stress conditions. We have identified 3 members of SGT gene family through RACE (Rapid Amplification of cDNA Ends) in addition to sgtl1 reported earlier. The amino acid sequence deduced from the ORF's showed homology (45-67 %) to the reported plant SGTs. The expression of the genes was differentially modulated in different organs in W. somnifera and in response to external stimuli. Salicylic acid and methyl jasmonate treatments showed up to 10 fold increase in the expression of sgt genes suggesting their role in defense. The level of expression increased in heat and cold stress indicating the role of sterol modifications in abiotic stress. One of the members, was expressed in E. coli and the enzyme assay showed that the crude enzyme glycosylated stigmasterol. W. somnifera expresses a family of sgt genes and there is a functional recruitment of these genes under stress conditions. The genes which are involved in sterol modification are important in view of medicinal value and understanding stress.

Compatibility of garlic (Allium sativum L.) leaf agglutinin and Cry1Ac δ-endotoxin for gene pyramiding.

δ-Endotoxins produced by Bacillus thuringiensis (Bt) have been used as bio-pesticides for the control of lepidopteran insect pests. Garlic (Allium sativum L.) leaf agglutinin (ASAL), being toxic to several sap-sucking pests and some lepidopteran pests, may be a good candidate for pyramiding with δ-endotoxins in transgenic plants for enhancing the range of resistance to insect pests. Since ASAL shares the midgut receptors with Cry1Ac in Helicoverpa armigera, there is possibility of antagonism in their toxicity. Our study demonstrated that ASAL increased the toxicity of Cry1Ac against H. armigera while Cry1Ac did not alter the toxicity of ASAL against cotton aphids. The two toxins interacted and increased binding of each other to brush border membrane vesicle (BBMV) proteins and to the two important receptors, alkaline phosphatase (ALP) and aminopeptidase N (APN). The results indicated that the toxins had different binding sites on the ALP and APN but influenced mutual binding. We conclude that ASAL can be safely employed with Cry1Ac for developing transgenic crops for wider insect resistance.

Transcriptome analysis at mid-stage seed development in litchi with contrasting seed size.

Litchi is a sub-tropical fruit crop with genotypes that bear fruits with variable seed size. Small seed size is a desirable trait in litchi, as it improves consumers' preference and facilitates fruit processing. Seed specific transcriptome analysis was performed in two litchi genotypes with contrasting seed size to identify the genes associated with seed development. The transcriptomic sequence data from seeds at mid-development stages (16-28 days after anthesis) were de-novo assembled into 1,39,608 Trinity transcripts. Out of these, 6325 transcripts expressed differentially between the two contrasting genotypes. Several putative genes for salicylic acid, jasmonic acid and brassinosteriod pathways were down-regulated in seeds of the small-seeded litchi. The putative regulators of seed maturation and seed storage were down-regulated in the small-seeded genotype. Embryogenesis, cell expansion, seed size and stress related Trinity transcripts exhibited differential expression. Further studies on gene characterization will reveal the early regulators of seed size in litchi. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s13205-021-03098-8.