Effect of okra plant resistance on transmission rate of okra enation leaf curl virus by its vector whitefly, Bemisia tabaci

The present study aimed to investigate the effect of age of the okra plants that showed varying whitefly resistance responses on the transmission rate of okra enation leaf curl virus (OELCV) by its vector whitefly Bemisia tabaci. The OELCV infected whitefly adults were collected from whitefly colonies and were challenged on the test okra accessions (Upl mona 2, Co 1, Arka anamika and AE 64) of differential ages which were individually caged (7, 10 and 15 d after germination) with glass chimney and the number of such whiteflies used were at the rate of 2, 4, 6, 8, 10, 12, 14 and 20 adults per plant. Observations were made on the virus symptom expression 30 d after challenge. The efficiency of transmission was determined. The efficiency of transmission of OELCV was the highest (maximum T and P*, 0.80, 1.00 and 0.08, 0.10) when 7 d old seedlings were inoculated (Arka anamika and AE 64 respectively) and transmission had decreased as the age of seedlings increased. The estimated transmission rate for single whitefly (P*) increased with an increase in the number of whiteflies used per plant. Okra plant resistance to B. tabaci significantly changed the transmission rates of OELCV on okra. Understanding the resistance mechanisms of the okra accessions and interactions between plant viruses and their insect host can pave the way for novel approaches to protect plants from virus infection

STUDIES ON GENETIC DIVERSITY IN Vigna mungo L. Hepper IN YMV HOTSPOT

            The present investigation was conducted to examine the 41 blackgram genotypes  along with one check (T-9) to study the genetic diversity. Analysis of variance showed highly significant differences among 41blackgram genotypes for 9 quantitative characters studied. Maximum genotypic and phenotypic variance was recorded for percentage of disease infection, single plant seed yield, and number of pods per plant.   Minimum   GCV and PCV were recorded for pod length, days to 50% flowering, number of seeds per pod. High heritability was recorded for percentage of disease infection, single plant seed yield, and number of pods per plant. High heritability coupled with high genetic advance as percent of mean was recorded for percentage of disease infection, single plant seed yield. Genetic diversity estimated in 41 blackgram genotypes using Mahalanobis’s D2 statistic. Forty one genotypes were grouped into seven clusters by Tocher method (Mahalanobis Euclidean Distance) cluster analysis.  The  maximum  inter-cluster  distance  was  observed  between  cluster VI  and  cluster  VII and maximum intra-cluster distance was observed in cluster VI.  Cluster VII showed maximum cluster mean value for seed yield per plant. Among all the characters, seed yield per plant and percentage of disease infection contributes maximum

Susceptibility baselines for the invasive mealybugs Phenacoccus manihoti and Paracoccus marginatus (Hemiptera: Pseudococcidae) in cassava ecosystem against selected neonicotinoid insecticides

In recent years, an invasive cassava mealybug Phenacoccus manihoti has been threatening cassava cultivation alongside another invasive papaya mealybug Paracoccus marginatus which invaded the country more than a decade ago. In order to evaluate their responses against the commonly used neonicotinoid insecticides: thiamethoxam 25 WG and imidacloprid 17.8 SL,  acute toxicity experiments to determine the susceptibility baselines in populations of two invasive mealybugs in the cassava agro-ecosystem, namely, cassava mealybug P. manihoti and papaya mealybug P. marginatus were performed upto 15 generations. A systemic uptake method was used for the bioassay. The LC50 values of thiamethoxam for F1 generation were 3.298 ppm whereas it was 1.066 ppm for F15 in cassava mealybug. The LC50 values of F1 generation were 2.014 ppm and that of F15 generation was 1.384 ppm when tested with imidacloprid. In the case of papaya mealybug, the LC50 values ranged from 6.138 ppm (F1) to 2.503 ppm (F15) for thiamethoxam and 7.457 ppm (F1) to 3.231 ppm (F15) for imidacloprid. All the susceptibility indices calculated were less than threefold. The rate of resistance development was negative in all cases showing that none of the tested populations harboured any resistance without insecticidal selection pressure. Tentative discriminating doses were fixed for both chemicals with the help of LC95 values obtained from the bioassay experiments, namely five ppm for both thiamethoxam and imidacloprid in the case of cassava mealybug and 10 ppm and 15 ppm, respectively, for thiamethoxam and imidacloprid in the case of papaya mealybug.          

Rice Aroma: Biochemical, Genetics and Molecular Aspects and Its Extraction and Quantification Methods

Aroma in rice is unique and a superior grain quality trait, varieties especially Basmati and Jasmine-type are fetching a high export price in the International markets. Among the identified volatile aroma compounds, 2AP (2 acetyl-1-pyrroline) is believed to be the distinctive biochemical compound contributing the flavor in rice. Genetically, aroma in rice arises by the phenotypic expression of spontaneous recessive mutations of the OsBadh2 gene (also known as fgr/badh2 /osbadh2/os2AP gene) which was mapped on chromosome 8. An 8-bp deletion in the exon 7 of this gene was reported to result in truncation of betaine aldehyde dehydrogenease enzyme whose loss-of-function lead to the accumulation of a major aromatic compound (2AP) in fragrant rice. Among the different sampling methods and analytical techniques for the extraction and quantification of scentedness, simultaneous distillation extraction (SDE) is traditional and normalized, whereas solid-phase micro extraction (SPME) and supercritical fluid extraction (SFE) are new, very simple, rapid, efficient and most importantly solvent-free methods. These methods are coupled with Gas Chromatography–Mass Spectrometry (GC–MS), Gas Chromatography-Flame Ionization Detector (GC-FID) and/or Gas chromatography olfactometry (GC-O) and also with sensory evaluation for readily examining 2AP compound found in rice. The major factor affecting the aroma in rice was their genetic makeup. However, the aroma quality may be differed due to different planting, pre-harvest and postharvest handling and storage. For a more extensive elucidation of all effective and fundamental factors contributing to fragrance, it is essential to explore target quantitative trait loci (QTLs) and their inheritance and locations

Integration of phenylammoniumiodide (PAI) as a surface coating molecule towards ambient stable MAPbI3 perovskite for solar cell application

In the present work, different hybrid perovskites were synthesized by gradual concentration variation of larger cation of phenylammoniumiodide (PAI) and methylammoniumiodide (MAI) in PbI2 solution with the aim of improving the stability of MAPbI3 film and photovoltaic efficiency. To understand the properties of perovskite like structural, optical, thermal, morphological and chemical state, extensive characterizations such as XRD, UV–visible spectroscopy, FE-SEM, SEM, EDX and XPS were performed. The role of PAI was investigated further with the use of DFT studies. The DFT results confirmed that the PAI was passivated on the surface of MAPbI3 with most stable arrangement. The stable arrangement revealed the formation of ᴫ-ᴫ interactions within the phenyl rings, which shielded the MAI crystals and thereby resulted in enhanced stability of the perovskites. Highly protected perovskite consequently yielded high- performance solar cell device with enhanced stability under 60% humidity, high temperature exposure and longer time stability even when directly exposed to normal room temperature. The new investigation of capping techniques with the use of bigger organic molecules, high performance solar cell with low device costs could emerge. This could lead to unprecedented rapid progress on power conversion efficiency (PCE). Thus, more stable organic-inorganic hybrid perovskites could be developed for future applications

Estimation of morphological and molecular genetic diversity in blackgram [Vigna mungo (L.) Hepper] under YMV hotspot regime

A phenotypic and molecular diversity study was conducted using seven traits and 19 SSR markers in a collection of 26 black gram genotypes. Phenotypic characterization was based on seven yield and yield related variable. The  field experiment  was  laid  out  at  Panboli village (YMV hotspot)  of Tirunelveli District in Tamilnadu during summer 2017. Genetic divergence was estimated on the basis of D2 values and 26 genotypes under study were grouped into six clusters by Tocher’s method. Seed yield per plant followed by Plant height and number of pods per plant contributed to the genetic divergence. The genetic distance announced using DICE dissimilarity co-efficient indicated highest divergence of 1.0 between VBN 8 and AUBG 17 and between VBN 8 and AUBG 19. The dendogram constructed using the DICE dissimilarity co-efficient between genotypes showed four apparent clusters based on marker allele distribution. Divergence was noted between the dissimilarity matrices based on the molecular and phenotypic diversity based on agronomic data.&nbsp

New intramolecular α-arylation strategy of ketones by the reaction of silyl enol ethers to photosensitized electron transfer generated arene radical cations: construction of benzannulated and benzospiroannulated compounds

Efficient intramolecular α-arylation of ketones is achieved by the reaction of silyl enol ethers to photosensitized electron transfer (PET) generated arene radical cations. The arene radical cations are generated by one-electron transfer from the excited state of the methoxy-substituted arenes to ground-state 1,4-dicyanonaphthalene (DCN). This arylation strategy has provided the unique opportunity of constructing five- (23), six- (18), seven- (25) and eight-membered (27) benzannulated as well as benzospiroannulated (34) compounds. The explanation for the formation of 27 has been advanced by considering the proximity between the arene radical cation and silyl enol ether due to the self-coiling in the aqueous environment

Baseline Susceptibility and Resistance Monitoring of Pyridalyl 10 EC against Plutella xylostella L. (Lepidoptera: Plutellidae) in Tamil Nadu, India

In vitro studies were conducted to assess the baseline toxicity of pyridalyl 10 EC against Diamondback moth, Plutella xylostella collected from four major cabbage and cauliflower growing tracks in Tamil Nadu. The LC50 and LC95 values of Pyridalyl 10 EC from F1 to F15 generations declined from 2.528 to 0.447 ppm and 14.978 to 2.235 ppm respectively. The susceptibility index to pyridalyl was 5.655 based on LC50 and 6.702 based on LC95. With regard to number of generation required for ten-fold decrease in LC50 was 19.934. Considering the F15 population of P. xylostella as the most susceptible, the tentative discriminating dose arrived was 2.235 ppm. Resistance monitoring studies of P. xylostella across locations viz. Coimbatore, Hosur, Ooty, and Oddanchatram indicated that the per cent resistance ranged from the lowest of 2.008 ppm in Oddanchatram to the highest of 3.696 ppm in Hosur. The Pyridalyl 10 EC reflected the highest resistance ratio of 8.268 fold in Hosur field population and the lowest resistance ratio of 4.492 fold in Oddanchatram field population