Mayabini Jena

Correction: Use of molecular markers in identification and characterization of resistance to rice blast in India

Rice blast disease caused by Magnaporthe oryzae is one of the most destructive disease causing huge losses to rice yield in different parts of the world. Therefore, an attempt has been made to find out the resistance by screening and studying the genetic diversity of eighty released rice varieties by National Rice Research Institute, Cuttack (NRVs) using molecular markers linked to twelve major blast resistance (R) genes viz Pib, Piz, Piz-t, Pik, Pik-p, Pikm Pik-h, Pita/Pita-2, Pi2, Pi9, Pi1 and Pi5. Out of which, nineteen varieties (23.75%) showed resistance, twenty one were moderately resistant (26.25%) while remaining forty varieties (50%) showed susceptible in uniform blast nursery. Rice varieties possessing blast resistance genes varied from four to twelve and the frequencies of the resistance genes ranged from 0 to 100%. The cluster analysis grouped the eighty NRVs into two major clusters at 63% level of genetic similarity coefficient. The PIC value for seventeen markers varied from 0 to 0.37 at an average of 0.20. Out of seventeen markers, only five markers, 195R-1, Pi9-i, Pita3, YL155/YL87 and 40N23r corresponded to three broad spectrum R genes viz. Pi9, Pita/Pita2 and Pi5 were found to be significantly associated with the blast disease with explaining phenotypic variance from 3.5% to 7.7%. The population structure analysis and PCoA divided the entire 80 NRVs into two sub-groups. The outcome of this study would help to formulate strategies for improving rice blast resistance through genetic studies, plant-pathogen interaction, identification of novel R genes, development of new resistant varieties through marker-assisted breeding for improving rice blast resistance in India and worldwide.

Effect of Pretilachlor on Soil Enzyme Activities in Tropical Rice Soil.

Pretilachlor treatments, namely, recommended dose at 600xa0g a.i. ha−1 (RD), double the recommended dose at 1200xa0g a.i. ha−1 (2RD), ten times of the recommended dose at 6000xa0g a.i. ha−1 (10RD) along with control, were used to study the effects of pretilachlor on soil enzymes in tropical rice soil. Pretilachlor, at recommended dose completely dissipated 30 days after herbicide application. Twenty days after herbicide application, the dehydrogenase activity was inhibited up to 27u2009%, 28u2009% and 40u2009% of initial values of RD, 2RD and 10RD treatments, respectively. Increase in fluorescein diacetate hydrolase activity was observed during the first 25 days post herbicide application up to 29u2009%, 36u2009% and 10u2009% of initial values of RD, 2RD and 10RD treatments, respectively. β-Glucosidase activity in the experiment did not provide a specific trend. In general, urease and acid phosphatase activities were not influenced by pretilachlor application. There were significant differences in alkaline phosphatase activities among the treatments until 25 days after herbicide application. Hence, pretilachlor may cause short term transitory changes in soil enzyme parameters. However, it has negative impact on soil enzymes at very high dose.

Molecular phylogeny of endophytic Dendryphiella: In quest of finding out ancestor of important rice seed Micro-Flora

Thirteen endophytic non sporulating fungi present in healthy seeds of rice cultivars, popular in coastal India, were isolated by ‘host tissue transplant ’method. Those were identified by the molecular technique and phylogenetic analysis by Phylogeny fr software was done. The phylogeny tree of 32 taxa including 27 Dendryphiella species and five Cochliobolus miyabeanus spp. was rendered. There were two major groups. Five Cochliobolus miyabeanus spp. (out group) were together the smaller cluster whereas all the Dendryphiella species with same internal node. The Dendryphiella group was further subdivided in two sub groups where 10 marine Dendryphiella and 17 terrestrial endophytic Dendryphiella grouped in two different sister groups. The high bootstrap values for each subcluster justified their grouping in the proper bunch. This analysis indicated that marine and ‘terrestrial endophytic Dendryphiella ’had common ancestors.

Occurance, pathogenicity, characterization of Fusarium fujikuroi causing rice bakanae disease from Odisha and in vitro management

The present investigation was carried out to asses the incidence of bakanae disease in Odisha, characterization of the isolates and its management with fungicides. The disease incidence ranging from 1–25.50 percent on different rice varieties was recorded in five districts mainly, Cuttack, Sambalpur, Bargarh, Ganjam and Jajpur. These regions were identified as new hot spots for the disease. The disease was observed to a significant extent in most of the commercially growing varieties with maximum disease incidence on Pooja (19.0% and 24.5% respectively for two seasons). A significant variation was observed among the isolates with respect to cultural, morphological characters and degree of pathogenicity. All the ten isolates were grouped into highly virulent group. The amplification of tef-1alpha gene generated approx 700 bp bands. In phylogenetic analysis, based on tef-1alpha gene region, overall two major groups were formed. The F.fujikuroi isolates FJ1 (Kisannagar), FJ2 (Khurda), FJ3 (Tangi-Chodwar) and FJ9 (Chandikole) belonged to same group whereas FJ4 (Cuttack), FJ5 (Jajpur), FJ6 (Kisannagar-2), FJ7 (Sambalpur), FJ8 (Bargarh) and FJ10 (Ganjam) are in a separate group with other world isolates. Among the ten systemic fungicides tested, all found effective with 100 percent reduction in mycelial growth. All the three tested Trichoderma spp. were found effective under in vitro with complete inhibition and lyses of the pathogen mycelium. Seed treatment with Carbendazim 50% WP @1 g/kg of seeds found effective with maximum germination, vigor index and disease reduction.

Insights into the structure–function relationship of brown plant hopper resistance protein, Bph14 of rice plant: a computational structural biology approach

Brown plant hopper (BPH) is one of the major destructive insect pests of rice, causing severe yield loss. Thirty-two BPH resistance genes have been identified in cultivated and wild species of rice Although, molecular mechanism of rice plant resistance against BPH studied through map-based cloning, due to non-existence of NMR/crystal structures of Bph14 protein, recognition of leucine-rich repeat (LRR) domain and its interaction with different ligands are poorly understood. Thus, in the present study, in silico approach was adopted to predict three-dimensional structure of LRR domain of Bph14 using comparative modelling approach followed by interaction study with jasmonic and salicylic acids. LRR domain along with LRR-jasmonic and salicylic acid complexes were subjected to dynamic simulation using GROMACS, individually, for energy minimisation and refinement of the structure. Final binding energy of jasmonic and salicylic acid with LRR domain was calculated using MM/PBSA. Free-energy landscape analysis revealed that overall stability of LRR domain of Bph14 is not much affected after forming complex with jasmonic and salicylic acid. MM/PBSA analysis revealed that binding affinities of LRR domain towards salicylic acid is higher as compared to jasmonic acid. Interaction study of LRR domain with salicylic acid and jasmonic acid reveals that THR987 of LRR form hydrogen bond with both complexes. Thus, THR987 plays active role in the Bph14 and phytochemical interaction for inducing resistance in rice plant against BPH. In future, Bph14 gene and phytochemicals could be used in BPH management and development of novel resistant varieties for increasing rice yield.

Toxicological effect of underutilized plant, Cleistanthus collinus leaf extracts against two major stored grain pests, the rice weevil, Sitophilus oryzae and red flour beetle, Tribolium castaneum

Toxicity and repellency activity of Cleistanthus collinus (Roxb.) (CC) leaf extracts were evaluated against rice weevil, Sitophilus oryzae (L.) and red flour beetle, Tribolium castaneum (Herbst) under laboratory condition. Five concentration(s) (1%, 1.5%, 2%, 2.5% and 4%) with two controls (acetone and water) treatments along with deltamethrin were used for direct and contact residual toxicity. The insect that survived after CC exposure were transferred to an untreated feeding substrate and the population buildup of subsequent two generation were recorded after 30 (F1) and 60 days (F2). In the contact residual toxicity, highest CC concentration (4%) produced 75% mortality in S. oryzae and 62.5% mortality in T. castaneum during 7 days of exposure, whereas in direct toxicity the mortality were 81% and 58% respectively, for S. oryzae and T. castaneum. The long term effect of CC was apparent in both the insect species, where F2 populations were significantly decreased in the CC treatments. CC treatment at 4% produced similar adult mortality in comparison to deltamethrin at 1%. In addition, repellent activity of CC extracts was observed against both S. oryzae and T. castaneum. This is the first step towards assessing the scientific basis for the understanding the effectiveness of CC extracts against stored grain pests and it could be a viable eco-friendly option for stored grain insect pest management.