Effect of sowing time and crop geometry on the Capsaicinoid content in Bhoot Jolokia (Capsicum chinense Jacq.).

Capsicum species are not only cultivated as vegetable and condiment crop but are also incorporated into a number of medicinal preparations in the ancient literature around the world. 'Naga chilli' or 'Bhoot Jolokia' (Capsicum chinense Jacq.) is a chilli variety indigenous to the northeast region of India and has been recognized as one of the hottest chilli in the world. It has also been used conventionally in treating various human ailments since time immemorial by the indigenous people of the northeast India. Capsaicin and dihydrocapsaicin are the two major members of the so-called capsaicinoid family, which includes other minor analogues, and usually account for at least 90 % of the pungency trait in chilli fruits. In the present study, determination of Capsaicinoid content of Bhoot Jolokia (Capsicum chinense Jacq.) under different sowing time and spacing was done. In the Scoville Organoleptic test, the highest Scoville Heat Unit (SHU) value was found in September 15 sowing fruits and the lowest in the February 15 sowing fruits. Fruit produced from spacing 105 cm × 105 cm showed highest Scoville Heat Unit. In High Performance Liquid Chromatography analysis, highest amount of capsaicinoid was also found in September 15 sowing while fruits produced from spacing 105 cm × 105 cm showed highest amount of capsaicinoid. Identification of Nordihydrocapsaicin, Capsaicin and Dihydrocapsaicin was done by comparing the retention time of sample with those of standard.

Arbuscular mycorrhizal fungi-mediated activation of plant defense responses in direct seeded rice (Oryza sativa L.) against root-knot nematode Meloidogyne graminicola.

Rhizosphere is the battlefield of beneficial and harmful (so called phytopathogens) microorganisms. Moreover, these microbial communities are struggling for their existence in the soil and playing key roles in plant growth, mineralization, nutrient cycling and ecosystem functioning. In the last few decades, some consistent pattern have been detected so far that link soil community composition and functions with plant growth and development; however, it has not been studied in detail. AM fungi are model organisms, besides potential role in nutrient cycling; they modulate biochemical pathways directly or indirectly which lead to better plant growth under biotic and abiotic stress conditions. In the present investigations, we have elucidated the AM fungi-mediated activation of plant defense responses against Meloidogyne graminicola causing root-knot disease in direct seeded rice (Oryza sativa L.). The study describes the multifarious effects of Funneliformis mosseae, Rhizophagus fasciculatus, and Rhizophagus intraradices inoculated individually or in combination under glasshouse conditions in rice plants. It was found that F. mosseae, R. fasciculatus and R. intraradices when applied individually or in combination modulated the biochemical and molecular mechanisms in the susceptible and resistant inbred lines of rice. AM inoculation significantly increased various plant growth attributes in plants with simultaneous decrease in the root-knot intensity. Among these, the combined application of F. mosseae, R. fasciculatus, and R. intraradices was found to enhance the accumulation and activities of biomolecules and enzymes related to defense priming as well as antioxidation in the susceptible and resistant inbred lines of rice pre-challenged with M. graminicola. The application of F. mosseae, R. fasciculatus and R. intraradices, induced the key genes involved in plant defense and signaling and it has been demonstrated for the first time. Results of the present investigation advocated that the application of F. mosseae, R. fasciculatus and R. intraradices, particularly a combination of all three, not only helped in the control of root-knot nematodes but also increased plant growth as well as enhances the gene expression in rice. Thus, it proved to be an excellent biocontrol as well as plant growth-promoting agent in rice even when the crop is under biotic stress of the root-knot nematode, M. graminicola.

Mapping quantitative trait loci responsible for resistance to Bakanae disease in rice.

BACKGROUND: Bakanae or foot rot disease caused by Fusarium fujikuroi [teleomorph: Gibberella fujikuroi (Sawada) Ito] is emerging as a serious disease in rice. The disease causes both quantitative and qualitative losses to the grains under the field conditions. Breeding for resistance to Bakanae disease is a promising strategy to manage this emerging disease. In this study, we used a population of 168 F14 recombinant inbred lines (RILs) derived from two indica rice parents Pusa 1342, a highly resistant variety and Pusa Basmati 1121, a highly susceptible variety to map quantitative trait loci (QTLs) governing resistance against Bakanae disease. RESULTS: The disease reaction of 168 F14 RILs were measured on the seedlings inoculated using Fusarium fujikuroi culture using high-throughput screening protocol under glasshouse conditions. Utilizing inclusive composite interval mapping, three QTLs governing resistance to Bakanae were identified, namely qBK1.1, qBK1.2 and qBK1.3 which accounted 4.76, 24.74 and 6.49 % of phenotypic variation, respectively. The major effect QTL designated qBK1.2 was mapped in 0.26 Mb region between RM5336 and RM10153. A total of 55 annotated genes were identified within the identified QTL region qBK1.2. CONCLUSIONS: The novel QTLs identified in this study are useful resource for efficiently breeding rice cultivars resistant to Bakanae disease. This is the first report on identification of QTLs governing resistance against Bakanae in rice using inclusive composite interval mapping strategy in a RIL population.