Plant Disease Control: Understanding the Roles of Toxins and Phytoalexins in Host-Pathogen Interaction

Naturally, plant habitats are exposed to several potential effects of biotic and different abiotic environmental challenges. Several types of micro-organisms namely; bacteria, viruses, fungi, nematodes, mites, insects, mammals and other herbivorous animals are found in large amounts in all ecosystems, which lead to considerable reduction in crop productivity. These organisms are agents carrying different diseases that can damage the plants through the secretion of toxic-microbial poisons that can penetrate in the plant tissues. Toxins are injurious substances that act on plant protoplast to influence disease development. In response to the stress effect, plants defend themselves by bearing some substances such as phytoalexins. Production of phytoalexins is one of the complex mechanisms through which plants exhibit disease resistance. Several findings specifically on phytoalexins have widen the understanding in the fields of plant biochemistry and molecular biology. However, this review reports the interaction of toxins and phytoalexins in plant-pathogen cycle, research progress on the association of phytoalexins with plant disease resistance as well as the role of the phytoalexins in plant disease control

Plant disease control: understanding the roles of toxins and phytoalexins in host-pathogen interaction

Naturally, plant habitats are exposed to several potential effects of biotic and different abiotic environmental challenges. Several types of micro-organisms namely; bacteria, viruses, fungi, nematodes, mites, insects, mammals and other herbivorous animals are found in large amounts in all ecosystems, which lead to considerable reduction in crop productivity. These organisms are agents carrying different diseases that can damage the plants through the secretion of toxic-microbial poisons that can penetrate in the plant tissues. Toxins are injurious substances that act on plant protoplast to influence disease development. In response to the stress effect, plants defend themselves by bearing some substances such as phytoalexins. Production of phytoalexins is one of the complex mechanisms through which plants exhibit disease resistance. Several findings specifically on phytoalexins have widen the understanding in the fields of plant biochemistry and molecular biology. However, this review reports the interaction of toxins and phytoalexins in plant-pathogen cycle, research progress on the association of phytoalexins with plant disease resistance as well as the role of the phytoalexins in plant disease control

Biogas Production: A Comparative Study of Chicken Droppings (Poultry Waste) and Banana Peels as the Gas Source

Biogas has been increasingly used in generating energy in the deregulated energy market. Biogas production has been identified as a sustainable approach to mitigating the effect of climate change and global warming. This work conducted a comparative study of biogas production from poultry waste (Chicken droppings) and banana peels under the same operating conditions. 100g of each sample was mixed with 200cm³ of water for poultry waste and 400cm³ for banana peels and loaded into four cylindrical digesters. Each container was shaken to ensure a homogenous mixture and fermentation. Biogas was measured using the water displacement method for 14 days at an average of 27.7oC. The pH, temperature, and concentration were observed to affect biogas production. Within 14 days, 1556cm3 and 755cm3 of biogas were produced for poultry waste and banana peels. This shows that poultry waste produces more biogas than banana peels. Hence, it can be deduced that poultry waste is potentially a more promising feedstock for biogas production than banana peels; and can provide an alternative energy source for the local community in place of the conventional fossil fuel source

Capsaicin and dihydrocapsaicin determination in chili pepper genotypes using ultra-fast liquid chromatography

Research was carried out to estimate the levels of capsaicin and dihydrocapsaicin that may be found in some heat tolerant chili pepper genotypes and to determine the degree of pungency as well as percentage capsaicin content of each of the analyzed peppers. A sensitive, precise, and specific ultra fast liquid chromatographic (UFLC) system was used for the separation, identification and quantitation of the capsaicinoids and the extraction solvent was acetonitrile. The method validation parameters, including linearity, precision, accuracy and recovery, yielded good results. Thus, the limit of detection was 0.045 µg/kg and 0.151 µg/kg for capsaicin and dihydrocapsaicin, respectively, whereas the limit of quantitation was 0.11 µg/kg and 0.368 µg/kg for capsaicin and dihydrocapsaicin. The calibration graph was linear from 0.05 to 0.50 µg/g for UFLC analysis. The inter- and intra-day precisions (relative standard deviation) were <5.0% for capsaicin and <9.9% for dihydrocapsaicin while the average recoveries obtained were quantitative (89.4%–90.1% for capsaicin, 92.4%–95.2% for dihydrocapsaicin), indicating good accuracy of the UFLC method. AVPP0705, AVPP0506, AVPP0104, AVPP0002, C05573 and AVPP0805 showed the highest concentration of capsaicin (12,776, 5,828, 4,393, 4,760, 3,764 and 4,120 µg/kg) and the highest pungency level, whereas AVPP9703, AVPP0512, AVPP0307, AVPP0803 and AVPP0102 recorded no detection of capsaicin and hence were non-pungent. All chili peppers studied except AVPP9703, AVPP0512, AVPP0307, AVPP0803 and AVPP0102 could serve as potential sources of capsaicin. On the other hand, only genotypes AVPP0506, AVPP0104, AVPP0002, C05573 and AVPP0805 gave a % capsaicin content that falls within the pungency limit that could make them recommendable as potential sources of capsaicin for the pharmaceutical industry

Synthesis and characterization of copper nanoparticles using different concentration of rice straw

New copper nanoparticles (CuNPs) have been synthesized via chemical reduction method in the presence of rice straw as supports and seaweed as a stabilizer. Characterizations of the CuNPs were carried out using UV-visible spectroscopy (UV-vis), Fourier Transform Infrared (FT-IR), Field Emission Scanning Electron Microscopy (FESEM), and Energy Dispersive X-ray (EDX). The UV-vis adsorption spectra confirm the formation of CuNPs through the peaks of the surface plasmon resonance (SPR) bands around 500 to 600 nm. Morphological characterization showed the formation of a spherical structure of the CuNPs. Similarly, EDX spectra showed that the nanoparticles produced are copper based. The size of nanoparticles formed by this method was controlled easily by using different concentration of rice straw.Keywords: Chemical Reduction, Copper Nanoparticle, Rice Straw; Seawee

The expression of target HSP70 gene and membrane stability determine heat tolerance in chili pepper

Experiments were carried out to study the mechanisms for heat tolerance in chili pepper (Capsicum annuum). To assess these mechanisms, six genotypes were evaluated for cellular membrane thermostability (CMT) and for HSP70 gene expression. The plants were grown in an experimental plant growth chamber. The mean value of CMT indicates that membrane integrity was not damaged by the high temperature treatment (50 °C) in most of the genotypes. The genotypes were classified as follows: heat-tolerant (greater than 60%), moderately tolerant (30% to 60%), and susceptible (less than 30%). The heat-tolerant plants recorded the highest CMTs at 89.27%, 88.03%, and 85.10% for AVPP0702, AVPP0116, and AVPP9905, respectively, which might be the reason for the change in their cell membrane thermostability. AVPP9703 and AVPP0002 showed CMTs of 15.87% and 18.43%, which might indicate their sensitivity to heat stress. Heat shock protein 70 kDa was identified and found to be differentially expressed under the heat stress. Under heat stress, significantly increased levels of the HSP70 gene were detected after 2 h of temperature treatment at 42 °C, which indicated that this gene is quickly and sharply induced by heat shock. This was true for all genotypes tested, which were significantly up-regulated by more than 36.9-, 7.10-, 3.87-, and 3-fold for AVPP0702, AVPP0116, AVPP0002, and AVPP9703, respectively. The HSP70 gene was found to be significantly down-regulated under heat stress in ‘Kulai’. AVPP0702, AVPP9905, and AVPP0116 could be considered as heat-tolerant genotypes, whereas ‘Kulai’ and AVPP9703 were found to be heat-sensitive genotypes in this investigation

Breeding for Anthracnose disease resistance in chili: progress and prospects

Chili anthracnose is one of the most devastating fungal diseases affecting the quality and yield production of chili. The aim of this review is to summarize the current knowledge concerning the chili anthracnose disease, as well as to explore the use of marker-assisted breeding programs aimed at improving anthracnose disease resistance in this species. This disease is caused by the Colletotrichum species complex, and there have been ongoing screening methods of chili pepper genotypes with resistance to anthracnose in the field, as well as in laboratories. Conventional breeding involves phenotypic selection in the field, and it is more time-consuming compared to molecular breeding. The use of marker-assisted selection (MAS) on the basis of inheritance, the segregation ratio of resistance to susceptibility, and the gene-controlling resistance may contribute to the development of an improved chili variety and speed up the selection process, while also reducing genetic drag in the segregating population. More importantly, by using molecular markers, the linkage groups are determined dominantly and co-dominantly, meaning that the implementation of a reliable method to produce resistant varieties is crucial in future breeding programs. This updated information will offer a supportive direction for chili breeders to develop an anthracnose-resistant chili variety

Genotype × Environment interaction and stability analyses of yield and yield components of established and mutant rice genotypes tested in multiple locations in Malaysia

Genotypes evaluation for stability and high yielding in rice is an important factor for sustainable rice production and food security. These evaluations are essential especially when the objective of the breeding program is to select lines with high adaptability and stability. This study was conducted to investigate G × E interaction over ten environments across the peninsular Malaysia for yield stability in fifteen rice genotypes comprising twelve mutant lines and three established varieties. The experiment was laid out in a randomized complete block design with three replications across the environments. Yield component traits were evaluated over multiple harvests and measured as number of tillers per hill, filled grains per panicle, grain weight per hill and yield per hectare. Data analyses were through analyses of variance and stability analyses were conducted for univariate and multivariate stability parameters. The pooled analysis of variance showed highly significant differences among genotypes, locations, seasons, and genotypes by environment (G × E interaction) for all the traits. Based on univariate (bi, , σi2, Wi2, YSi) and multivariate (AMMI and GGE biplot) stability parameters, rice genotypes were classified into three main groups. The first group are genotypes having high stability along with high yield. These genotypes are widely adapted to diverse environmental conditions. The second group is a genotype that exhibited high yield but low stability, this genotype is suitable for specific environments. The last group is genotypes with low yield and high stability. Genotypes in this class are more suitable for breeding specific traits or yield component compensation such as the capacity to recover rapidly from stresses. Significant rank correlations were measured for regression slope (bi), deviation from regression (), Shukla stability variance (), Wricke’s ecovalence (), and Kang stability statistic (YSi) for all the traits

Blast disease intimidation towards rice cultivation: a review of pathogen and strategies to control

Rice blast is the most destructive disease to rice production globally. The objective of this review is to know the fundamentals of rice blast disease and to know the different methods for controlling blast disease. Rice blast disease has been recognised in more than 85 rice-producing countries worldwide. Currently, more than 100 R genes for blast resistance have been identified in rice. These resistance genes can be introgressed into a susceptible variety through marker-assisted backcrossing. Infested residues and seeds are the primary inoculum sources to spread the disease. Considering the importance of this disease, various management approaches have been practiced to control blast disease. The use of resistant varieties is an important measure to manage the disease. This review will provide use fulfacts about the pathogen and its epidemiology, assessment of resistance genes and effective control measure of rice blast disease through breeding and management. This update information will be helpful and guide to the research students and rice breeders to develop durable blast resistant rice varieties. So farmers will able to manage the blast disease in future