Genome-wide identification, characterization and expression analysis of the expansin gene family under drought stress in tea (Camellia sinensis L.)

During several developmental processes, expansins contribute to cell enlargement by promoting cell wall loosening. To explore the biological roles of expansins during drought stress response and to characterize different expansins in tea, we performed a detailed analysis of the expansin gene family covering phylogeny, gene structure, profiling of gene expression and co-expression network analysis. We identified a total of 40 expansin genes in the tea genome belonging to 3 subfamilies, out of which 29 tea expansins belong to EXPA, 9 to EXLA and 2 to EXPB subfamilies. A minimum of 3 and a maximum of 13 exons are present in the gene structure of expansins. Presence of drought stress responsive cis-acting elements in the upstream of promoter regions of 40% of the identified expansins shows that the putative expansins may have been involved in tea plant’s response to drought stress. At least 15 out of the 40 expansin genes are found to be differentially expressed in response to drought in each of the drought stress related public datasets analysed in-silico. TEA022767 belonging to EXPA subfamily is seen to be upregulated during drought stress, as revealed from the analysis of all three publicly available bio-projects. Co-expression network analysis shows that TEA022767 and TEA032954 form a connecting link between two expression correlation groups that further signifies their role in drought stress response in tea. This study helps to interpret and to understand the biological roles of diverse expansin genes in tea plants under drought stress conditions

Molecular cloning, expression and computational analysis of a water stress inducible copper-containing amine oxidase gene (CuAO) from tea plant [Camellia sinensis (L.) O. Kuntze]

Copper-containing amine oxidase (CuAO) is the enzyme known to play diversity of function in plant responses to environmental stresses through its reaction products. Here, for the first time we report full length cDNA encoding CuAO protein from a drought tolerant tea cultivar. It was found to be 785 bp long with a 70 bp 5.-UTR, 193 bp 3.-UTR, 522 bp mORF and a polyA adenylational signal. It codes for a poly-peptide of 173 amino acids having predicted molecular weight and isoelectric point of 19 KDa and 7.75 respectively. Heterologous expression and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) analysis of the protein in Escherichia coli revealed similar size as predicted by in silico analysis. Blastp analysis and template based homology modeling in Phyre2 has identified a copper amine oxidase domain with ligand binding site for copper at residue 123 (Histidine) which suggests its probable role in plant responses to environmental stresses. Interestingly, no signal peptide sequence was detected in the predicted protein which is in contrast to the CuAO so far reported in plants. Although, in slico analysis of the protein have indicated its probable structure and functions, further functional characterization is needed to better understand its role during drought and other environmental stresses in tea.Key words: Camellia sinensis, copper amine oxidase, homology modeling, molecular cloning

Rubisco-bis-phosphate oxygenase (RuBP)- A potential housekeeping gene for qPCR assays in tea

The present experiment is an effort to find a stable reference gene in Camellia sinensis and Camellia assamica under different biotic and abiotic stresses. This study evaluate the variation in gene expression across tea leaf tissues in nine experiments. The suitability of 18S rRNA, 26S rRNA, rubiscobis- phosphatase oxygenase (RuBP) and Camellia tubulin (CaT) as reference genes were validated by geNorm and BestKeeper programs. The finding reveals 18S rRNA and RuBP to be the most stably expressed housekeeping genes, the latter being the first report of its kind in tea. The finding paves the way for their application in accurate quantification of trait specific gene expression and other genomic studies in tea.Keywords: Camellia sinensis, Camellia assamica, qPCR, BestKeeper, geNorm, housekeeping gen

Identification and validation of stable reference genes in camellia species

We aimed at finding and validating a stable reference gene in Camellia sinensis and Camellia assamica from a set of four putative housekeeping genes in various samples exposed to different experimental conditions mainly biotic and abiotic stresses. Variation in gene expression across Camellia sinensis leaf tissues exposed to nine different kind of experimental sets was studied. The suitability of 18S rRNA, 26s rRNA, rubisco bis phosphatase (RuBP) and camellia actin (Act) as reference genes were validated by geNorm and BestKeeper programs and revealed 18S rRNA and RuBP to be the most stably expressing housekeeping gene. We therefore recommend use of RuBP as a stable reference gene for normalisation of transcripts abundance experiments in tea leaf samples

Impact of endophytic colonization by entomopathogenic fungi on the behavior and life history of the tobacco peach aphid Myzus persicae var. nicotianae

Entomopathogenic fungi can adopt an endophytic lifestyle and provide protection against insect herbivores and plant pathogens. So far, most studies have focused on Beauveria bassiana to increase plant resistance against abiotic and biotic stresses, while only little is known for other entomopathogenic fungi. In this study, we investigated whether root inoculation of sweet pepper (Capsicum annuum L.) by the entomopathogenic fungi Akanthomyces muscarius ARSEF 5128 and B. bassiana ARSEF 3097 can improve resistance against the tobacco peach aphid Myzus persicae var. nicotianae. First, dual-choice experiments were performed to test the hypothesis that the fungi deter aphids via modifying plant volatile profiles. Next, we tested the hypothesis that endophytic colonization negatively affects aphid life history traits, such as fecundity, development and mortality rate. Aphids were significantly attracted to the odor of plants inoculated with A. muscarius over non-inoculated plants. Plants inoculated with A. muscarius emitted significantly higher amounts of β-pinene than non-inoculated plants, and significantly higher amounts of indole than B. bassiana-inoculated and non-inoculated plants. Inoculation with the fungal strains also caused significantly higher emission of terpinolene. Further, both aphid longevity and fecundity were significantly reduced by 18% and 10%, respectively, when feeding on plants inoculated with A. muscarius, although intrinsic rate of population increase did not differ between inoculated and non-inoculated plants. Sweet pepper plants inoculated with B. bassiana ARSEF 3097 did not elicit a significant behavioral response nor affected the investigated life history traits. We conclude that endophytic colonization by entomopathogenic fungi has the potential to alter olfactory behavior and performance of M. persicae var. nicotianae, but effects are small and depend on the fungal strain used

Emerging role of plant long non coding RNAs (lncRNAs) in salinity stress response

Salinity stress typically occurs due to excessive accumulation of water-soluble salts i.e., NaCl, which can further induce osmotic stress, ionic stress as well as oxidative stress in plants, imposing many harmful effects on the growth and development of plants. However, plants respond to salinity stress through a range of cellular mechanisms which provides enhanced tolerance against salinity stress. Genetic regulation of salinity stress response through protein coding transcripts has already been extensively studied; however, involvement of non-coding transcripts such as long noncoding RNAs has recently received significant attention as an important molecule in regulating the plant response during salinity stress. Several salinity stress responsive long non coding RNAs have also been identified and characterized in various plant species. This review is an attempt to critically discuss the role of lncRNAs during salinity stress in plants

Coinfections as an aetiology of acute undifferentiated febrile illness among adult patients in the sub-Himalayan region of north India

Background & objectives: In India, certain geographic regions witness simultaneous outbreaks of two or more diseases like scrub typhus, dengue fever, malaria, leptospirosis and chikungunya during monsoon and post-monsoon period, sharing common indication of acute febrile illness. The objective of the present study was to assess the prevalence of coinfections among patients with acute undifferentiated fevers (AUF) admitted in a tertiary care hospital in the northern hilly state of Himachal Pradesh, India. Methods: This was a hospital based open cohort study conducted over a period of two months (September and October) in 2016. All the patients above the age of 18 yr admitted in medical wards and fulfilling the definition of AUF were included. The patients diagnosed with dual infections were the subjects of the study. Standard guidelines were used for case definitions of scrub typhus, dengue, chikungunya, malaria and leptospirosis. Results: Dual infections were noted in 16 patients admitted with AUF. The most common coinfection was scrub typhus and dengue, reported in 10 patients. Scrub typhus and leptospirosis coinfection was observed in three patients. Dengue and chikungunya was observed in one patient. Scrub typhus, dengue and vivax malaria was detected in one patient. Scrub typhus and vivax malaria was detected in one patient. Out of the 10 cases positive for both scrub and dengue, four had no history of travel outside Himachal Pradesh. All three cases positive for both scrub and leptospirosis were indigenous without any history of travel outside Kangra, Himachal Pradesh. The outcome of all the patients was with full recovery. Interpretation & conclusion: The study established the presence of coinfections (mainly dengue fever and leptospirosis) as a cause of AUF in the study area, which is a nonendemic region. The role of easily available and widely performed serological tests in the aetiological diagnosis of AUF is significant. Studies are required to determine the normal titres in the local population before using the imported commercially available serological tests in the diagnosis of AUF