Red Rot Disease Research Articles

Morphological, Cultural and Physiological Variations among Isolates of Colletotrichum Falcatum went That Cause Red Rot Disease of Sugarcane

Sugarcane is an important economical cash crop grown over an area of about 5.07 Mha in India. Red rot disease caused by the fungus Colletotrichum falcatum Went., is the most important and the dreaded disease affecting adversely the production of millable canes in India. Five isolates of C. falcatum were procured from ISSR, Lucknow; the culture was maintained on slants and Petri plates at 29°C. Variation in the cultural, morphological and physiological characteristics among the 5 isolates was investigated. These isolates were morphologically differentiated into two distinct groups: light colour and dark colour types based on the colony colour character. Three isolates (RR-08, RR-02 and RR-07) in the dark type produced gray colour colonies whereas isolates Cf-09 and Cf-08 in the light type had white colour colonies. The growth rate among all isolates varied from 10.6 to 11.9 mm.d-1 and was not significantly different. The five isolates produced setae and conidia that were hyaline, one-celled, falcate or sickle-shaped. The conidia of all isolates ranged between 31.2 and 36.5 μm in length and from 10.1 and 11.2 μm μm in width. All isolates were varied in their physiological characteristics. The optimum physical parameters for mycelial growth of the five strains was found to be 30°C for temperature, 5.5 (for four isolates viz., Cf-09, Cf-08, RR-08, RR-07) and 6.0 (for isolate RR-02) for pH. Host extract media maintained the highest mycelial growth in all the five isolates followed by PD broth. Dextrose and potassium nitrate were found to the best sources of carbon and nitrogen, respectively for maximum mycelial growth of Cf-09, Cf-08, RR-08 and RR-02 isolates while glucose and sodium nitrate were the best source of carbon and nitrogen, respectively for RR-07 isolate of C. falcatum. We have found that Colletotrichum falcatum isolates were culturally, morphologically and physiologically dissimilar.

Antifungal properties of rhamnolipid produced by Pseudomonas aeruginosa DS9 against Colletotrichum falcatum.

The rhamnolipid biosurfactant (RL-DS9) extracted from the bacterial strain Pseudomonas aeruginosa DS9 was evaluated for its antifungal activity against Colletotrichum falcatum that causes red rot in sugarcane. The surface tension (ST) reduction, biosurfactant production, and antifungal activity of biosurfactant against C. falcatum were investigated by using the medium with different carbon sources and it was found to be maximum in glucose. Moreover, highest reduction of ST and production of biosurfactant was achieved at 4.5% (w/v) concentration of glucose. The efficacy of RL-DS9 was compared with a commercially available rhamnolipid (RL-R95) using microtitre plate assay. Results showed that at 100 μg ml(-1) concentration RL-DS9 exhibited 86.6% inhibition against C. falcatum spore germination, and in the same concentration RL-R95 showed 83.3% inhibition. From liquid chromatography-mass spectrometry (LC-MS) analysis, it was revealed that only two similar congeners Rha-(C10 ) and Rha-Rha-(C10:1 ) were found to be in common among both the rhamnolipids. In the plant bioassay test, it was noted that red rot incidence was reduced on the sugarcane plants treated with RL-DS9. This is the first report that rhamnolipid biosurfactant produced by Pseudomonas aeruginosa DS9 could be able to control red rot disease of sugarcane caused due to the infection with the fungus Colletotrichum falcatum.

Evaluation of Streptomyces spp. for effective management of Poria hypolateritia causing red root-rot disease in tea plants

A field study was conducted to evaluate the efficacy of indigenous biocontrol agents such as Streptomyces griseus and Streptomyces lydicus along with Bacillus subtilis and Trichoderma harzianum for controlling red root rot disease of tea plants. In response to biological treatments, disease incidence, green leaf yield, biometric and physiological parameters and organoleptic characters of made tea were assessed. Among the thirteen treatments tested, soil drenching of carbendazim was superior in terms of reducing red root rot incidence followed by combination of S. griseus and T. harzianum recorded in two consecutive field experiments. In contrast, the maximum green leaf yield and plant growth was achieved in soil application of these biocontrol agents. However, the performance of this dual combination of biocontrol agents was on par with systemic fungicide in terms of disease control. Correspondingly, the biometric, physiological and biochemical parameters were also considerably increased in biologically treated plants when compared to untreated control. The disease increased from 38.7% to 47.6% in untreated control plots and those plants were unhealthy in terms of leaf yellowing, stunted growth with heavy flowering, drying of branches and sudden death of bushes. The tea quality parameters such as theaflavin and thearubigin contents were significantly increased in the range of 0.75–1.43% and 10.38–13.22% respectively in biocontrol treated plants. This was also reflected in tea liquor characteristics. Our results suggested that the combination of biocontrol agents represent a promising alternative for effective management of red root rot disease in tea plants.

Suppression of red rot disease by Bacillus sp. based biopesticide formulated in non-sterilized sugarcane filter cake

Red rot disease affects sugarcane production adversely throughout the world. Intensive cropping and uninterrupted use of chemicals results in evolution of new pathotypes which can infect the resistant cultivars. Bacillus sp. inhabiting plant rhizosphere can protect the plants from multiple pathogens. In the present study, two antagonistic strains Bacillus subtilis NH-100 and Bacillus sp. NH-217 were able to maintain their population at 9.0 log CFU g−1 in sugarcane filter cake until nine months. These strains were compatibile to the indigenous bacteria of sugarcane filter cake which maintained their population at 7.8–8.0 log CFU g−1. The developed bioformulation induced the activity of various defense-related enzymes (0.6–6.9 change in absorbance min−1 g−1 of tissue), suppressed the red rot disease and enhanced crop yield under field conditions. This formulation could be used as potential biopesticide to control red rot disease of sugarcane.

Characterization of a novel fungal disease that infects the gametophyte of Pyropia yezoensis (Bangiales, Rhodophyta)

This study investigated a new fungal disease that attacks Pyropia yezoensis, an economically important red alga that is extensively cultured in China. An incidence was found in a P. yezoensis farm during mid to end November 2012 at Haizhou Bay, Jiangshu Province, China. Histopathology revealed that the naturally infected thalli were overwhelmed by a fungus, leading to progressive red rot symptoms. The causative agent was isolated, grown in pure culture, and identified as a member of the genus Alternaria by morphology and sequence analysis of the nuclear ribosomal DNA containing the internal transcribed spacer (ITS) region of ITS1 and ITS2. In artificial infection experiments on P. yezoensis blades, the fungal isolate was able to cause the same characteristic histopathology seen in natural infections. This fungal isolate grew well at a wide range of temperatures (8–36 °C) and at low salinities (5–50 ‰). In an orthogonal test used to determine the effects of environmental factors (temperature, salinity, and conidia concentration) on disease expansion, it was found that higher temperatures and lower salinities easily caused red rot disease, with the optimal conditions for disease development being 23 °C, 24 ‰ salinity, and a conidia concentration of 105 mL−1. This is the first report to show that Alternaria causes red rot disease in P. yezoensis.

Genetic Analysis of Resistance Gene Analogues from a Sugarcane Cultivar Resistant to Red Rot Disease

AbstractOne of the important approaches for disease control in sugarcane is to develop a disease‐resistant variety; this may be accomplished through identification of resistance genes in sugarcane. In this study, PCR primers targeting the conserved motifs of the nucleotide‐binding site (NBS) class and kinase class of the resistance gene analogues (RGAs) were used to amplify the RGAs from a red rot‐resistant sugarcane cultivar (Saccharum spp. hybrid) HSF 240. Upon subcloning and sequencing, fifteen putative RGAs were identified. These RGAs shared 63–98% identity to the reported disease‐resistant genes in the NCBI GenBank database. Deduced amino acid sequences also showed the presence of expected conserved domains characteristic of RGAs. Phylogenetic analysis indicated that these RGAs clustered with R genes from other plant species. The findings will be useful for studying disease‐resistant genes in sugarcane.

Biochemical characterization of Pyropia yezoensis-AP1 strain accompanies the resistance reaction to the red rot disease pathogen, Pythium porphyrae

The biochemical profile of the Pyropia yezoensis-AP1 strain, a strain which shows resistance to red rot disease, was compared with that of a normal P. yezoensis cultivar. Levels of chlorophyll a, phycoerythrin, and phycocyanin were higher in P. yezoensis-AP1 than those in the normal P. yezoensis cultivar. Two-dimensional electrophoresis found a total of 132 and 128 distinct spots for total protein samples of P. yezoensis-AP1 and P. yezoensis, respectively. About 89.6 % of the total components were common to both P. yezoensis-AP1 and P. yezoensis, and 10.4 % were more abundant in the P. yezoensis-AP1 than P. yezoensis. The amount of total free amino acid in P. yezoensis-AP1 was less than that in the P. yezoensis cultivar, but taurine, glutamic acid, citrulline, and arginine content were higher in the P. yezoensis-AP1 strain. The porphyran content of P. yezoensis-AP1 (11.9 ± 0.5 % dry weight) was higher than that of P. yezoensis cultivar (9.5 ± 0.4 % dry weight). In the porphyran fraction, the content of 3,6-anhydro-L-galactose was higher in P. yezoensis-AP1 than P. yezoensis, and sulfate content was higher in the P. yezoensis cultivar than P. yezoensis-AP1. The results indicate that the difference of chemical composition between P. yezoensis-AP1 and P. yezoensis cultivar helps to explain the increased resistance to red rot disease in the AP1 strain. This finding provides a good starting point for the development of more resistant strains of P. yezoensis that will reduce the incidence of red rot disease on Pyropia farms.

A new screening method for Ganoderma philippii tolerance in tropical Acacia species

Red root rot disease caused by Ganoderma philippii is one of the most economically important diseases of tropical Acacia species. Research on field control of the disease has to date focused on inoculum reduction, silviculture practices and application of biological control agents. Incorporation of tolerant genotypes, a key component of integrated disease management, has not been adequately explored because of a lack of reliable and quick screening protocols. Recently, we developed a more rapid method of screening for red root rot tolerance in Acacia mangium, A. crassicarpa and A. mangium A. auriculiformis hybrid planting stock, in which groups of five, 6-week-old plants were subjected to inoculum consisting of a rubber (Hevea brasiliensis) wood block culture of the pathogen held within a polythene bag. As symptoms start to appear 10 weeks after inoculation, experiments can be completed in a six-month period instead of the years needed by the traditional pot system. Using this technique we were able to identify variations in tolerance and/or susceptibility to G. philippii in A. mangium, A. crassicarpa and A. mangium × A. auriculiformis hybrid planting stock in a more consistent manner. Tolerant and susceptible genotypes subsequently have been selected for further experiments or crosses. While the ultimate goal of this study was to develop and deploy high-yielding Acacia genotypes that are also tolerant to red root rot disease, results of the current screening studies may also be used to investigate the basis for tolerance to G. philippii in Acacia species.

Homeopathic drugs to control red rot disease in sisal plants

Sisal—Agave sisalana Perrine ex. Engelm—is a key economical and social crop in the semi-arid region of Brazil, especially in the Bahia state. Sisal is severely affected by Aspergillus niger Thieg, the causal agent of sisal red rot. Currently, existing control strategies are fruitless. Here, we tested different homeopathic drugs Carbo vegetabilis, Ferrum metallicum, Natrum muriaticum, phosphorus and sulphur at centesimal Hahnemannian (CH) dynamizations, of 3CH, 5CH, 7CH, 9CH and 12CH, on Aspergillus niger. We measured in vitro growth inhibition, sporulation and germination of Aspergillus niger during 12 days. We assessed in planta Aspergillus niger incidence and disease severity. Our results show that homeopathic drugs inhibited Aspergillus niger growth in vitro, in a dynamization-dependent way. Natrum muriaticum 5CH revealed the higher inhibition of 66 %, whereas sulphur 5CH yielded the lowest inhibition of 6.4 %. Spore production was stimulated using all homeopathic drugs at all dynamization levels, whereas spore germination was reduced. In planta assays revealed different results from in vitro assays, corroborating that in planta and in vitro effectiveness is different according to the homeopathic drugs applied. Here, disease incidence was not reduced significantly, but disease severity was lower in treated plants, of 27.8 % using Ferrum metallicum 9CH than in control trials, of 73.6 %. Overall, our findings suggest that homeopathic drugs could be a good strategy to control Aspergillus niger incidence in sisal plants.

Molecular profiling of systemic acquired resistance (SAR)-responsive transcripts in sugarcane challenged with Colletotrichum falcatum.

Red rot disease of sugarcane caused by Colletotrichum falcatum is one of the serious constraints affecting the productivity of the crop. The strategy of employing systemic acquired resistance (SAR) against red rot yielded consistently good results at field level. However, elucidation of genes involved in the induction of SAR continues to be a challenging area of research for a critical understanding of red rot disease resistance in sugarcane. Here, temporal expression of 22 putative defense-related genes were analyzed by semiquantitative reverse transcription-PCR (RT-PCR) in red rot-susceptible cultivar (CoC 671) with response to priming using various SAR inducers, viz. benzothiadiazole (BTH), salicylic acid (SA), and C. falcatum elicitor. Among the 22 genes studied, 12 transcripts were found to be differentially expressed, of which seven transcripts represent phenylpropanoid pathway and five transcripts represent resistant gene analogues (RGAs). Differentially regulated phenylpropanoid pathway genes such as cinnamic acid 4-hydroxylase, 4-coumarate:coenzyme A ligase, chalcone synthase, and chalcone reductase were reported to play a major role in the regulation of phytoalexin synthesis, whereas R genes such as NBS-LRR genes and basal layer antifungal peptide (BAF) genes were upregulated upon SAR induction in response to pathogen challenge. These upregulated genes presumably play a potential role in SAR induction and might contribute to defense against C. falcatum.

The knight of sugar industry: T. S. Venkatraman (1884-1963)

Tiruvadi Sambasiva Venkatraman (TSV) was a plant breeder. In response to a call from Pundit Madan Mohan Malaviya, he made it his mission to develop high-yielding varieties of sugarcane for manufacturing sugar and making it available as a sweetening agent and an energy source for the malnourished children of India. Using Saccharum officinarum, then under cultivation in India, as the female parent, he artificially fertilized it with pollen from S. barberi, which grew wild in Coimbatore. After 4-5 recurrent backcrossings of S. officinarum Chi wild Sorghum spontaneum with S. officinarum as the female parent, TSV selected the `rare' interspecies hybrid cane varieties that resembled sugarcane and had approximately 2.5 cm thick juicy stems containing 16-18% sucrose - nearly 35 times more than what occurred in parent stocks. The hybrid canes matured quickly, were resistant to waterlogging, drought, and to the red-rot disease caused by Glomerella tucumanensis (Sordariomycetes: Glomerellaceae), and to the sereh-virus disease. Most importantly, they were amenable for propagation using stem cuttings. In recognition of the development of high-yielding sugarcane varieties, TSV was conferred the titles Rao Bahadur, Rao Sahib, and Sir by the British Government, and Padma Bhushan by the Republic of India. In the next few decades, consequent to TSV's work, India turned into the second largest sugar producer in the world, after Brazil. The hybrid sugarcane varieties developed are the foundational stocks for new sugarcane x bamboo hybrids, and for possible resistance to Puccinia megalocephala (Pucciniomycetes: Pucciniaceae) and Ustilago scitaminea (Ustilaginomycetes: Ustilaginaceae) using molecular techniques.

The sugarcane defense protein SUGARWIN2 causes cell death in Colletotrichum falcatum but not in non-pathogenic fungi.

Plants respond to pathogens and insect attacks by inducing and accumulating a large set of defense-related proteins. Two homologues of a barley wound-inducible protein (BARWIN) have been characterized in sugarcane, SUGARWIN1 and SUGARWIN2 (sugarcane wound-inducible proteins). Induction of SUGARWINs occurs in response to Diatraea saccharalis damage but not to pathogen infection. In addition, the protein itself does not show any effect on insect development; instead, it has antimicrobial activities toward Fusarium verticillioides, an opportunistic fungus that usually occurs after D. saccharalis borer attacks on sugarcane. In this study, we sought to evaluate the specificity of SUGARWIN2 to better understand its mechanism of action against phytopathogens and the associations between fungi and insects that affect plants. We used Colletotrichum falcatum, a fungus that causes red rot disease in sugarcane fields infested by D. saccharalis, and Ceratocystis paradoxa, which causes pineapple disease in sugarcane. We also tested whether SUGARWIN2 is able to cause cell death in Aspergillus nidulans, a fungus that does not infect sugarcane, and in the model yeast Saccharomyces cerevisiae, which is used for bioethanol production. Recombinant SUGARWIN2 altered C. falcatum morphology by increasing vacuolization, points of fractures and a leak of intracellular material, leading to germling apoptosis. In C. paradoxa, SUGARWIN2 showed increased vacuolization in hyphae but did not kill the fungi. Neither the non-pathogenic fungus A. nidulans nor the yeast S. cerevisiae was affected by recombinant SUGARWIN2, suggesting that the protein is specific to sugarcane opportunistic fungal pathogens.

Complete Genome Sequence of the Sugar Cane Endophyte Pseudomonas aurantiaca PB-St2, a Disease-Suppressive Bacterium with Antifungal Activity toward the Plant Pathogen Colletotrichum falcatum

The endophytic bacterium Pseudomonas aurantiaca PB-St2 exhibits antifungal activity and represents a biocontrol agent to suppress red rot disease of sugar cane. Here, we report the completely sequenced 6.6-Mb genome of P. aurantiaca PB-St2. The sequence contains a repertoire of biosynthetic genes for secondary metabolites that putatively contribute to its antagonistic activity and its plant-microbe interactions.

Isolation and evaluation of a strain of Pyropia yezoensis (Bangiales, Rhodophyta) resistant to red rot disease

Red rot disease (Pythium porphyrae) resistant strains of Pyropia yezoensis, AP1 and AP2, were isolated from live cells taken from lesions on infected P. yezoensis blades. The degree of resistance of these strains to red rot disease was evaluated over a range of environmental conditions including temperature (10, 15, and 20 °C), salinity (20, 26, and 32 ppt), and pH (7.5, 8.0, and 8.5). These conditions are within the range that red rot disease naturally occurs on Pyropia blades. P. yezoensis and Pyropia suborbiculata with low and high partial resistance to red rot disease, respectively, were used as controls. Infection with red rot disease occurred under all environmental conditions. The incidence, severity, and expansion of the disease increased with increasing temperature and decreasing salinity and pH. The resistance of the strains P. yezoensis-AP1 and P. yezoensis-AP2 was higher than that of P. yezoensis, but lower than that of P. suborbiculata. The degree of resistance was not significantly different between the AP1 and AP2 strains. These strains can therefore be considered to exhibit stable partial resistance to P. porphyrae, and as a good starting point for the development of more resistant strains that will prevent or reduce the incidence of red rot disease on Pyropia farms.

Role of Endochitinase Gene and Efficacy of Trichoderma Against Colletotrichum falcatum Went. Causing Red Rot Disease in Sugarcane

Role of endochitinase (ech42) gene in Trichoderma was worked out to prove the efficacy against most dreaded red rot disease of sugarcane caused by Colletotrichumfalcatum Went. Trichoderma spp. along with Trichoderma harzianum strain and Aspergillusawamori were tested against the virulent pathotypes of C. falcatum (Cf08, Cf09 and Cf401) under in vitro and in vivo conditions. T. harzianum was significantly able to control the incidence of red rot disease in highly susceptible sugarcane cultivar. PCR-Random amplified polymorphic DNA amplification results clearly separated T. harzianum 1, 2 and 3 from rest of the biological agents. T. harzianum 1 strain was highly diverse and making distant relationship with rest of the T. harzianum bioagents. Wide genetic distance was observed among the red rot pathogens and biological agents. The ech42 specific primers pair amplified a corresponding fragment of 1.5 kb in all Trichoderma spp. Thus, the presence of the ech42 gene was found to be correlated with the biocontrol activity of Trichoderma species. These findings clearly supported that ech42 gene is more specifically responsible for controlling the red rot incidence in sugarcane.

Efficacy of various fungicides and indigenous biocontrol agents against red root rot disease of tea plants

An experiment was conducted to study the effectiveness of contact, systemic and botanical fungicides, and indigenous biocontrol agents in controlling red root rot disease of tea plants. In general, all tested bioagents, the combination of Pseudomonas fluorescens and Trichoderma atroviride reduced red root disease incidence recorded in two consecutive field experiments. Among the fourteen treatments tested, soil drenching of systemic fungicides was superior but similar to the combination between P. fluorescens and T. atroviride. In contrast, the maximum green leaf yield and plant growth was achieved when soil application of biocontrol agents was carried out. However, the performance of these biocontrol agents under various combinations was on par with systemic fungicides, but superior to botanical fungicides. Correspondingly, the physiological and biochemical parameters were also greatly increased in plants in several treatments when compared to untreated control. The disease increased from 31.5 % to 40.0 % in untreated control plots and those plants were unhealthy in terms of leaf yellowing, stunted growth with heavy flowering, drying of branches and sudden death of bushes. The tea quality parameters were significantly improved in treated plants including total liquor colour, thearubigins, theaflavins, highly polymerized substance and caffeine contents.

Expression of phenolics and defence-related enzymes in relation to red root rot disease of tea plants

Red root rot caused by Poria hypolateritia is a dreadful disease in tea plant due to sudden death of bushes. In response to fungal pathogen, variation in the defence-related enzymes was investigated. The infected tea root was undertaken to study about various defence-related and pathogen-related enzymes. The infected root, as a prime response to disease attack, was subjected to the analysis of phenolics, phenylalanine ammonia lyase, tyrosine ammonia lyase, peroxidase, polyphenol oxidase, catalase, chitinase, β-1,3-glucanase and protease were assayed. The results on assay of defence-related enzymes revealed that the activity was significantly higher in infected roots when compared with healthy roots. Phenolics were accumulated more in infected roots. The sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) analysis further confirmed the presence of induced pathogenesis-related proteins in the infected root tissues. The activity of all enzymes was increased up to threefold amount when compared with normal ones. The accumulation of defence enzymes in plants revealed the virulence of root pathogen in stimulating induced systemic resistance of tea plants and phytopathogenicity causing pathogenesis. This study exemplify to recognise underlying processes in causing infection and to identify the existence of host–pathogen relationship.

TOLERANSI TANAMAN PENEDUH POLYALTHIA LONGIFOLIA DAN PTEROCARPUS INDICUS TERHADAP Ganoderma sp.

Susceptibility of Urban Trees Polyalthia longifolia and Pterocarpus indicus to Infection of the red root rot fungus Ganoderma sp. Urban trees on the Gadjah Mada University (UGM) area play an important role in increasing environmental qualities as well as in supporting the teaching and learning processes. However, red root rot disease caused by Basidiomycete Ganoderma sp. has severely infected some existing urban trees. This experiment was aimed to determine the susceptibility of Polyalthia longifolia (glodokan) and Pterocarpus indicus (angsana) to the infection of Ganoderma sp. Identification of infected trees was performed in UGM area. Further steps were carried out to achieve those objectives : (1) isolation of Ganoderma spp. and testing of Koch’s postulate and (2) examination of the susceptibility of P. longifolia and P. indicus to infection of Ganoderma sp. The susceptibility test of P. longifolia and P. indicus to Ganoderma sp. indicated that P. longifolia was more resistant to fungal pathogen infection than that of P. indicus. Based on this experiment, it can be concluded that P. longifolia is a species that is more suitable than P. indicus. P. longifolia should be planted on the areas that have been infested with inocula of Ganoderma sp..

PLANT GROWTH-PROMOTING BACTERIAL ENDOPHYTES FROM SUGARCANE AND THEIR POTENTIAL IN PROMOTING GROWTH OF THE HOST UNDER FIELD CONDITIONS

SUMMARYTen endophytic bacteria were isolated from different sugarcane varieties growing in the Crop Research Centre, Pantnagar on nitrogen-free medium. Plant growth-promoting potential of the isolates was reported in terms of indole acetic acid (IAA) production, phosphorus solubilization, siderophore production and antagonistic action against the pathogenColletotrichum falcatum, which causes red rot disease in sugarcanein vitro. All the isolates were able to produce IAA (4.8–9 μg ml−1); three isolates (H3, H5 and H14) solubilized insoluble phosphorus on Pikovaskaya's agar; two isolates (H10 and H14) showed siderophore production on Chrome-azurol S (CAS) agar and antagonism againstC. falcatumwas exhibited by two isolates (H14 and H15) in a dual plate assay. 16 S rRNA sequencing identified isolates H3 and H12 asPseudomonasspp., and H8, H14 and H15 asBacillusspp. A field experiment on sugarcane was conducted with five plant growth-promoting bacterial endophytesPseudomonasspp. (H3 and H12) andBacillusspp. (H8, H14 and H15) along with standard strains ofGluconacetobacterandAzospirillumspp. Plant height, chlorophyll content, total nitrogen and cane length were significantly higher in almost all inoculated plants compared with the uninoculated control. An increase of 40% in cane yield over the control was obtained after inoculation with isolate H15 (Bacillusspp.). This was statistically on par with the standard endophyteGluconacetobacter diazotrophicus, which resulted in 42% increased cane yield. Identification of new diazotrophs and their promising results towards improving plant growth in the field suggest their use as inoculants in future.

Expression profiling of transcription factors (TFs) in sugarcane X Colletotrichum falcatum interaction

Sugarcane is one of the most important commercial crops in India, supporting the second largest agro-based sugar industry. However for more than a century, the production is imperiled by the most devastating fungus Colletotrichum falcatum Went, which causes red rot in sugarcane. Complex polyploidy and limited understanding on the inheritance to red rot resistance makes breeding efforts more complicated in sugarcane. Transcription factors (TFs) play a key role in regulating defense response, which offers much promise for the manipulation of metabolic pathways, potential in regulating multiple signaling networks leading to plant defense against pathogens. In order to better manage red rot disease in sugarcane, we sought to screen the TFs possibly involving in pathogen defense by analyzing 5 major defense-related TF classes (WRKY, bZIP, MYB, NAC and TLP). In this study two parallel sets of experiments were carried out to compare the differential regulation of these classes of TFs upon pathogen challenge and SAR priming. Among the 41 TFs studied, differential regulation of 24 TFs upon pathogen challenge and 15 TFs upon SAR inducer priming were observed. Comparison of incompatible interaction and SAR inducer priming revealed that 8 TFs were highly induced in both the cases. Collectively, the results showed that TFs which are significantly induced early may involve actively in triggering or co-ordinating defense against pathogen invasion.