Exploring Aluminum Tolerance at Seedling Stage in Rice (Oryza Sativa, Linn) by Using Modified Magnavaca Nutrient Solution

Aluminum (Al) toxicity is considered as one of the main constraints for crop production in acidic soil. This study was subjected to observe the response of root and shoot growth of eight rice varieties under Al stress in hydrophonic solution. A modified Magnavaca's solution was used to compare the effect of Al stress using different variables which were relative root elongation (RRE), relative shoot length (RSL) and relative root weight (RRW). The experiment was conducted in split-plot experimental design. Eight rice varieties were screened in four Al levels (0 μM, 540 μM, 750 μM, and 1,300 μM). Root length, shoot length,and root dry weight were measured after 7 days of treatment, then the RRE, RSL, and RRW were calculated. The results showed that Al significantly reduced RRE and RSL but increased RRW. RSL was reduced as the Al concentration increased while RRE reduction started only at 750 μM Al concentration. It was observed that RRW was significantly higher under 540 and 750 μM Al concentration. However, no significant difference was observed in 1,300 μM Al concentration. The increase in root weight is partly attributed by the thickening of the root wall, but this effect was diminished due to root hair inhibition under 1,300 μM Al concentration. Among these three variables observed, root and shoot lengths indicated better variables in determining Al tolerance in rice, compared to root weight. However, these variables were not sufficient to represent root and shoot growth inhibition, and not sufficient to be used solely for Al toxicity screenin

Genome-wide Association Analysis Tracks Bacterial Leaf Blight Resistance Loci In Rice Diverse Germplasm

Genome-wide association analysis of bacterial blight resistance to nine Xoo strains in 198 indica genotypes based on Efficient Mixed-Model Association eXpedited Model (EMMAX). Manhattan plots for nine Xoo strains (a) PXO61, (b) PXO86, (c) PXO79, (d) PXO71, (e) PXO112, (f) PXO99, (g) PXO339, (h) PXO349, and (i) PXO341. X-axis shows the SNPs along each chromosome; y axis is the − log10 (P-value) for the association. Significant SNPs are those beyond the red line having P-value < 1 × 10 −5. Quantile-quantile plots for nine Xoo strains (j) PXO61, (k) PXO86, (l) PXO79, (m) PXO71, (n) PXO112, (o) PXO99, (p) PXO339, (q) PXO349, and (r) PXO341. (PPTX 521 kb

Screening for Resistance in Selected Tomato Varieties against the Root-Knot Nematode <i>Meloidogyne incognita</i> in the Philippines Using a Molecular Marker and Biochemical Analysis

Tomato is a high-value vegetable crop widely cultivated in the Philippines, and its production is threatened by various stresses including infection by the root-knot nematode M. incognita. In this study, we checked for resistance to M. incognita in selected tomato germplasm collections and commercially available varieties using a bioassay method, the molecular marker Mi23 and biochemical analysis. Among the eight varieties tested, none showed a resistant reaction against M. incognita. Use of the molecular marker Mi23 yielded 430 bp in all the tomato varieties screened. Phylogenetic analysis using the neighbor-joining method revealed the clustering of consensus sequence of the varieties tested with the susceptible variety S. lycopersicum cv. M82-1-8 and a wild relative, S. pimpinellifolium isolate LA2184. The biochemical analysis showed varying responses among the varieties when they were inoculated with M. incognita. Increased levels of total antioxidant activity were observed in Diamante Max F1, Ilocos Red and Tm 2016 11-1, while total phenolic content was found to be elevated in Athena, Avatar TY F1 and Rosanna. Increased levels of ascorbic acid were observed in Athena and Avatar TY F1 even at 45 dpi. Even though these varieties showed elevated levels of the abovementioned biochemical parameters related to a resistance reaction, all of them showed highly susceptible reactions. Hence, this study showed that these tomato varieties have no resistance against M. incognita and that there is a need to identify other sources of resistance against M. incongita and produce resistant tomato cultivars adapted to local conditions

GENETIC DIVERSITY OF NATURAL POPULATIONS OF BACTROCERA OCCIPITALIS (BEZZI) AND B. PHILIPPINENSIS DREW AND HANCOCK (DIPTERA: TEPHRITIDAE) IN SELECTED MANGO PRODUCING AREAS IN THE PHILIPPINES USING MICROSATELLITES

Using nine microsatellite loci, the genetic diversity of natural populations of Bactrocera occipitalis and B. philippinensis was investigated. Estimates of genetic diversity based on allele number (na and ne), heterozygosity (Ho and He) and Shannon information index (I) revealed that the Cavite population was the most genetically diverse (na = 18.56; ne = 12.88; Ho = 0.58; He = 0.89; I = 2.55) and Pangasinan was the least (na = 7.89; ne = 8.94; Ho = 0.34; He = 0.87; I = 2.31). Among groups, the intermediates were the most genetically diverse (na = 25.44; ne = 15.30; Ho = 0.52; He = 0.92; I = 2.85) and B. philippinensis was the least (na = 17.44; Ho = 0.44; He = 0.90; I = 2.54). A low level of genetic diversity was detected among populations. Pangansinan and Palawan populations were the most related while Palawan and Guimaras populations were the least. Among groups, B. occipitalis and intermediates were the most related while B. occipitalis and B. philippinesis were the least. Dendrogram analysis indicated that B. occipitalis, B. philippinensis, and intermediates are not genetically distinct from each other

DNA fingerprinting at farm level maps rice biodiversity across Bangladesh and reveals regional varietal preferences

The development, dissemination, and adoption of improved rice varieties are imperative for global food and nutritional security. Knowledge of the crop’s distribution across agro-ecologies is important for impact assessment studies, varietal replacement strategies, and the development and implementation of agricultural policies. Bangladesh is the world’s 4th largest rice producer. Though traditional varieties (TVs) are abundant and valued throughout Bangladesh, population growth and vulnerability to climate change, necessitate efficient deployment of high-yielding stress-tolerant modern varieties (MVs). To aid agricultural policy and strategy this study aimed to accurately assess the distribution of MVs and TVs across Bangladesh during the rainfed rice-growing season. Information derived from a survey of rice production areas were compared and combined with DNA fingerprinting information from the same locations. Biodiversity of Bangladesh rice remained high. While TVs and first generation MVs of Bangladeshi and Indian origin were still commonly grown, recently released stress-tolerant MVs were adopted in large proportions in several districts. Although farmers successfully distinguished TVs from MVs grown in their fields, a considerable lack of authenticity among MVs was observed, pinpointing shortcomings in the seed supply chain. This study identifies focal points for extension work and validates DNA fingerprinting as reliable method for impact assessment studies