Efficiency of RAPD and SSR markers in assessing genetic diversity in summer onion (Allium cepa L.) genotypes

The genetic diversity assessment of agricultural crops is crucial for breeding programs aimed at enhancing crop yield, resistance to diseases, and adaptation to changing environmental conditions. In the present investigation, a comparative genetic relationship in sixteen onion genotypes was assessed utilizing dominant (RAPD) and co-dominant (SSR) marker systems. Ten RAPD and nine SSR markers showed genetic diversity remarkably and produced 503 and 107 amplicons respectively. Spearman rank correlation was used to compare the different efficiency parameters in two marker systems with respect to sixteen onion genotypes. The genetic relationship based on similarity matrix values between a pair of cultivars was higher for SSR markers than for the RAPD marker system. OPC-04 (RAPD primer) and ACM-004 (SSR primer) witnessed the highest poly-morphic bands along with other polymorphic markers that proved to be useful in grouping onion genotypes. Finally, dendrograms were constructed and compared following the mantel test to find out the genetic diversity among the germplasms. This study will be effective for a selection of efficient primers and suitable marker systems to distinguish the onion genotypes in the future

Fertilizer best management practices by SSNM and customized fertilizers for elephant foot yam (Amorphophallus paeoniifolius) cultivation in India

Elephant foot yam [Amorphophallus paeoniifolius (Dennst.) Nicolson] is an important tuber crop grown in many parts of India for its starchy corm and the average yield of this crop is far below the potential productivity of 100 tonnes/ha. One of the reasons attributed to the lower yield is the imbalanced application of essential plant nutrients. Site specific nutrient management (SSNM) is the application of plant nutrients based on the soil and crop need, yield target and developed with the aid of models such as QUEFTS. This paper gives the result of four year study conducted to calibrate and validate the QUEFTS model for elephant foot yam cultivation and the development of SSNM zonation maps and secondary and micronutrient fortified customised fertilizers for the crop in major growing environments of India. Data collected from different field experiments conducted in major elephant foot yam-production regions of India during 1968 to 2011 were used to calibrate the model. The derived parameters of minimum and maximum accumulation of N (130 and 460), P (900 and 2100) and K (100 and 170) are proposed as standard borderline values in the QUEFTS model for elephant foot yam. A linear increase in corm yield was suggested by the model with N, P and K uptakes of 3.97, 0.71, and 7.05 kg N, P and K/1 000 kg corm. The average NPK ratio in total plant dry matter was 5.56:1:9.88. Based on these results, the model was calibrated using historical data as well as by conducting field experiments. It can be observed that fertilizer best management practices by SSNM resulted in an average actual corm yield of 33.45 tonnes/ha, whereas, the model predicted a yield of 35 tonnes/ha. The results of the study showed good agreement between predicted and measured corm yields during the four years, which indicated that the calibrated model can be used to improve NPK fertilizer recommendations for elephant foot yam in India. Based on the results and using soil fertility maps and agro ecological unit maps, SSNM zonation maps and secondary and micronutrient fortified customised fertilizers were developed for major elephant foot yam growing environments of India

A comparison of efficiency parameters of SSR markers and genetic diversity analysis in Amorphophallus paeoniifolius (Dennst.) Nicolson

ABSTRACT Amorphophallus (elephant foot yam) is an herbaceous edible aroid crop which belongs to the family Araceae. The study was undertaken to identify the efficient SSR primer that could differentiate a set of 12 elephant foot yam genotypes. Various efficiency parameters, namely, Polymorphism Information Content (PIC), Marker Index (MI), Resolving Power (RP) and Diversity Index (DI) were studied for 11 primers. The relationship between the parameters was studied using Spearman rank correlation coefficient. Discrimination analysis was done to find out the most effective parameter. Finally Principal Coordinate Analysis (PCoA) and dendrogram was done to find out the genetic diversity among the germplasm. The SSR markers under this investigation will facilitate further studies in population genetics and utilization of A. paeoniifolius

Effect of Banana Bunchy Top Virus on the Heat Shock Protein Genes of Pentalonia nigronervosa during Temperature Susceptibility and Its Effect on Virus Transmission

Acquisition of plant viruses is known to exert various effects on vectors’ developmental biology. Pentalonia nigronervosa is the only known vector of banana bunchy top virus (BBTV), which is an economically detrimental virus infecting banana cultivars all over the world. In the present study, the developmental biology of viruliferous (Vr) and non-viruliferous (NVr) aphids was compared, with a marked reduction noted in the lifespan of aphids upon acquisition of BBTV. Among all the environmental parameters temperature is an important determinant of an insect’s abundance and geographical distribution. Temperature susceptibility of P. nigronervosa was scrutinized by comparing the mortality percentage and differential expression pattern of three heat shock proteins (Hsps; Hsp40, Hsp70, and Hsp90) at the mRNA level between NVr and Vr aphids. After exposure to different temperature stress (5 °C, 15 °C, 38 °C and 25 °C as control) highest mortality of Vr aphids were recorded at 5 °C. Analysis of expression levels of Hsp genes using qPCR showed that both cold and heat shock treatment stimulated higher expression of the three Hsps at various rates in Vr than NVr aphids.. Finally, the effect of temperature stress on the BBTV titer level and their transmission by P.nigronervosa was determined by absolute quantification. The transmission efficiency along with the virus titer was found to be the lowest at 15 °C compared to 38 °C. Overall, our results provide a novel insight into the intricate interaction between aphid fitness and thermal stress concerning the acquisition and transmission of BBTV, which could be a roadmap for the future epidemiological control system

A New Approach of Using Microscopic Image Aided Computer Programming for Evaluation of Porosity and Aerosity:Case Studies Using Polymeric Films and Functional Matrices

Porous polymer films of Poly-[Ethylene oxide] (PEO) are synthesized by solution casting technique using gamma irradiated: (a) PEO powder (S-series) and (b) PEO—methanol solution (L-series). Pore phase is though a defect, but form instantaneously during preparation. Optimization of the pore content, its size and distribution enable tailoring of associated properties for multifaceted applications of functional materials. The experimental pore-size distribution of the PEO films is studied using BET (Brunauer–Emmet–Teller) adsorption technique and reported as function of irradiation dose, irradiation state (S- and L-series) and polymer concentration (2 and 4 wt%). A newer computer program [PROGIMAGE-POR] is reported for determination of porosity, its size and distribution of perturbed PEO films using SEM images and correlated with that obtained from BET technique. The novelty of PROGIMAGE-POR lies in the exposure of newer or undetected pore regime in which experimental pore regime exists as a part. This method could be analyzed for mapping of porosity and average pore size. PROGIMAGE-POR bears the novelty of using image from either 2D or 3D imaging system and could be applied for intricate composite/layered system. Uniqueness of PROGIMAGE-POR lies in the exposure of newer pore regime in which experimental pores exist as a part. Theoretical analysis based on aerosity (2D-pores) and porosity (3D-pore) gives an estimate of the tortuous path of void space.</p

Effect of Neonicotinoids on Bacterial Symbionts and Insecticide-Resistant Gene in Whitefly, Bemisia tabaci

The silverleaf whitefly, Bemisia tabaci (Gennadius, Hemiptera: Aleyrodidae), is a major threat to field and horticultural crops worldwide. Persistent use of insecticides for the management of this pest is a lingering problem. In the present study, the status of sensitivity of B. tabaci to two neonicotinoids, imidacloprid and thiamethoxam, was evaluated. The expression pattern of two cytochrome P450 (cyp) genes and changes in the relative amount of symbionts in insecticide-treated B. tabaci were also assessed. Quantitative PCR (qPCR) studies indicate that the CYP6CM1 and CYP6CX1 genes were always expressed higher in imidacloprid-treated whitefly, suggesting a correlation between gene expression and the insect’s ability to detoxify toxic compounds such as insecticides. In addition, the thiamethoxam-treated population harbored higher Portiera and lower Rickettsia titers, whereas the imidacloprid-treated population harbored more Rickettsia at different time intervals. Interestingly, we also examined that an increase in exposure to both the insecticides resulted in a reduction in the mutualistic partners from their insect host. These differential responses of endosymbionts to insecticide exposure imply the complex interactions among the symbionts inside the host insect. The results also provide a deeper understanding of the molecular mechanism of resistance development that might be useful for formulating effective management strategies to control B. tabaci by manipulating symbionts and detoxifying genes