Diversity,plant growth-promoting traits,and biocontrol potential of fungal endophytes of Sorghum bicolor

The diversity of fungal endophytes in Sorghum bicolor was investigated in samples collected from 10 different geographical regions of Karnataka state, India. A total of 360 endophytes were isolated from leaf, stem, and root tissues and were assigned to 26 fungal species based on morphology and molecular characterization using ITS sequences. All the endophytes belonged to the phylum Ascomycota. The diversity (Shannon H, 2.57; Simpson_1-D, 0.92) and species richness (Margalef's, 4.68; Menhinick, 3.61) were found to be higher for the endophytes isolated from leaf tissues. The species evenness of the endophytic assemblage was strongly influenced by tissue type, followed by geographical location. The biocontrol potential of isolated endophytes was evaluated against economically destructive sorghum grain mould pathogens such as Fusarium thapsinum, Epicoccum sorghinum, Alternaria alternata, and Curvularia lunata using the dual culture method. Biocontrol potential was exhibited by 26 endophytic isolates, of which Trichoderma asperellum recorded broad-spectrum activity against target pathogens, followed by E. nigrum and A. longipes. Most (82%) endophytes showed plant growth-promoting traits. Biosynthesis of indole-3-acetic acid (IAA) was observed in 84% of isolates, and phosphate solubilization, siderophore production, and cellulase activity was observed in 69%, 23%, and 27% of isolates, respectively. Seeds treated with T. asperellum exhibited a significantly higher seed vigour index (2096), germination percentage (94%), and yield under greenhouse and field conditions. The results were substantiated by the confocal microscopy analysis, which clearly demonstrated the colonization of treated endophyte in root tissues. The present study reveals an ecofriendly approach to explore T. asperellum in sorghum disease management.     

Distribution of gymnemic acid in various organs of Gymnema sylvestre

The gymnemic acid contents in various organs of Gymnema sylvestre were investigated by High Performance Liquid Chromatography (HPLC) method. The results shows that the content of gymnemic acid in various organs, obviously different, was 54.29, 31.66, 28.82, 27.67, 25.39, 20.56 and 1.31 mg·g⁻¹ DW in shoot tips, flowers, nodes, leaves, internodes, roots and seeds, respectively. The highest gymnemic acid content (54.29 mg·g⁻¹ DW) was found in shoot tip, 1.96 fold higher than that in leaves (27.67 mg·g⁻¹ DW). Maximum quantity of gymnemic acid (35.39 mg·g⁻¹ DW) was observed in the young leaves, which was 1.52 times higher than that in old leaves (23.07 mg·g⁻¹ DW). The content of gymnemic acid in young, middle and old internodes was 26.47, 25.77 and 23.94 mg·g⁻¹ DW, respectively, all lower than that in leaves (27.67 mg·g⁻¹ DW), whereas the content of gymnemic acid in young, middle and old nodes was 27.96, 28.81 and 29.66 mg·g⁻¹ DW, respectively, all higher than that in leaves. The study provides the scientific evidences for the rational development and utilization of Gymnema sylvestre resources, since over exploitation of natural stands has caused depletion of these plants in nature. Foundation project: This work was supported by University Grants Commission, New Delhi (No. 33-88/2007 (SR))     

Rhizobacteria‐mediated resistance against the blackeye cowpea mosaic strain of bean common mosaic virus in cowpea (Vigna unguiculata)

BACKGROUND: The present study investigated the effect of seven Bacillus‐species plant‐growth‐promoting rhizobacteria (PGPR) seed treatments on the induction of disease resistance in cowpea against mosaic disease caused by the blackeye cowpea mosaic strain of bean common mosaic virus (BCMV). RESULTS: Initially, although all PGPR strains recorded significant enhancement of seed germination and seedling vigour, GBO3 and T4 strains were very promising. In general, all strains gave reduced BCMV incidence compared with the non‐bacterised control, both under screen‐house and under field conditions. Cowpea seeds treated with Bacillus pumilus (T4) and Bacillus subtilis (GBO3) strains offered protection of 42 and 41% against BCMV under screen‐house conditions. Under field conditions, strain GBO3 offered 34% protection against BCMV. The protection offered by PGPR strains against BCMV was evaluated by indirect enzyme‐linked immunosorbent assay (ELISA), with lowest immunoreactive values recorded in cowpea seeds treated with strains GBO3 and T4 in comparison with the non‐bacterised control. In addition, it was observed that strain combination worked better in inducing resistance than individual strains. Cowpea seeds treated with a combination of strains GBO3 + T4 registered the highest protection against BCMV. CONCLUSION: PGPR strains were effective in protecting cowpea plants against BCMV under both screen‐house and field conditions by inducing resistance against the virus. Thus, it is proposed that PGPR strains, particularly GBO3, could be potential inducers against BCMV and growth enhancers in cowpea. Copyright © 2009 Society of Chemical Industry     

Analysis of phenotypic variation and selection of superior genotypes of Balanites roxburghii Planch. from South India

Genetic Resources and Crop Evolution - Balanites roxburghii Planch. is an important medicinal plant of India and used in the treatment of various diseases and disorders. Seeds possess a high amount...     

Diversity of wood-apple (Limonia acidissima L., Rutaceae) genetic resources in South India

Genetic Resources and Crop Evolution - Wood-apple (Limonia acidissima L.) is an undomesticated nutritionally and medicinally potential monotypic tree species of the genus Limonia, which belongs to...     

Effect of Organic Manure and Crop Residue Based Long-Term Nutrient Management Systems on Soil Quality Changes under Sole Finger Millet (Eleusine coracana (L.) Gaertn.) and Groundnut (Arachis hypogaea L.) – Finger Millet Rotation in Rainfed Alfisol

A long-term experiment was conducted to evaluate the effect of integrated use of organic and inorganic sources of nutrients on soil quality and its relation to finger millet yield under two predominant crop rotations viz., groundnut–finger millet and finger millet monocropping in hot moist semiarid rainfed Alfisol soils in South India. Two experiments were laid out separately for each cropping system in a randomized complete block design with five treatments individually with FYM and maize residue-based combinations viz., Control (T1), FYM @ 10t ha ^?1 or Maize residue (MR) @ 5t ha ^?1 (T2), farm yard manure (FYM) @ 10t ha ^?1 or Maize residue (MR) @ 5t ha ^?1 + 50% RDF (Recommended Fertiliser Dose) N, P₂O₅ &; K₂O (T3), FYM @ 10t ha ^?1 or Maize residue (MR) @ 5t ha ^?1 + 100% RDF N,P₂O₅ &; K₂O (T4), Recommended N, P₂O₅ &; K₂O (T5). Thus, four sets of nutrient management systems were evaluated. The results showed that farm yard manure or maize residue application in combination with recommended dose of fertilizer significantly improved the soil physical, chemical, and biological properties compared to control and application of inorganic fertilizers alone. Based on evaluation of 19 soil quality parameters under each of the four nutrient management systems, the common key soil quality indicators emerged out were: organic C (OC), available nitrogen (N), available sulfur (S), and mean weight diameter (MWD) of soil aggregates. A significant correlation between the finger millet yield and the relative soil quality indices (RSQI) indicates the importance of soil quality in these semiarid Alfisol soils. The results and the methodology adopted in the present study could be of importance in improving the soil quality not only for the region of the study, but also in other identical soils and cropping systems across the world.     

匙羹藤酸在匙羹藤(Gymnema sylvesfre)不同器官的分布

利用高效液相色谱法(HPLC)测定匙羹藤(Gymmnema sylvestre)不同器官的匙羹藤酸含量.结果表明:不同器官的匙羹藤酸含量明显小同,在顶芽、花、节点、叶、节间、根和种子的匙羹藤酸含量分别为,54.29、31.66、28.82、27.67、25.39、20.56和1.31 mg·g-1 DW.在幼叶中,匙羹藤酸(35.39 mg·-1DW)含量最高,比老叶的匙羹藤酸(23.07 mg·g DW含量高1.52倍.幼年,中年和老年节间的匙羹藤酸含量分别为26.47、25.77和23.94 mg·g-1DW,均低于叶的匙羹藤酸含量,而幼嫩,中部节和老节点的匙羹藤酸含量分别为27.96、28.81和29.66 mg·g-1 DW,均高于叶的匙羹藤酸含量.因为过度开采引起了这些植物在自然界的损耗,本研究为匙羹藤资源的发展和利用提供了科学依据.     

Isolation and characterization of chitinolytic rhizobacteria for the management of Fusarium wilt in tomato

Sixty-three chitinase producing rhizobacteria (CRB) were isolated from 57 rhizospheric soil samples of tomato (Lycopersicon esculentum Mill.) growing in different regions of Karnataka, India. Among these, 13 CRB isolates were selected based on their ability to produce chitinase, colonize roots of tomato seedlings and reduce Fusarium wilt incidence. Four of these isolates produced statistically higher levels of chitinase and also zone of clearance/colony size (CZ/CS) ratios. One Bacillus subtilis isolate (CRB20) substantially reduced the severity of Fusarium wilt under greenhouse conditions. Combined application of chitin or crude fungal cell wall (CFCW) along with this isolate, substantially enhanced the ability of the isolate to colonize tomato roots and reduced the severity of Fusarium wilt. Under greenhouse conditions, amendments of chitin and CFCW along with isolate CRB20 significantly enhanced plant height, fresh weight, number of fruits per plant and average weight of fruit compared to the untreated control. The study clearly established the significance of CRB isolates and chitin/CFCW amendment in promoting plant growth and suppression of Fusarium oxysporum, and indicated the possibility of their use for Fusarium wilt management in tomato cultivation.