Siddhesh B. Ghag
Bhabha Atomic Research Centre
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Publication
Featured researches published by Siddhesh B. Ghag.
Plant Biotechnology Journal | 2014
Siddhesh B. Ghag; Upendra K. Singh Shekhawat; T. R. Ganapathi
Fusarium wilt, caused by Fusarium oxysporum f. sp. cubense (Foc), is among the most destructive diseases of banana (Musa spp.). Because no credible control measures are available, development of resistant cultivars through genetic engineering is the only option. We investigated whether intron hairpin RNA (ihpRNA)-mediated expression of small interfering RNAs (siRNAs) targeted against vital fungal genes (velvet and Fusarium transcription factor 1) in transgenic banana could achieve effective resistance against Foc. Partial sequences of these two genes were assembled as ihpRNAs in suitable binary vectors (ihpRNA-VEL and ihpRNA-FTF1) and transformed into embryogenic cell suspensions of banana cv. Rasthali by Agrobacterium-mediated genetic transformation. Eleven transformed lines derived from ihpRNA-VEL and twelve lines derived from ihpRNA-FTF1 were found to be free of external and internal symptoms of Foc after 6-week-long greenhouse bioassays. The five selected transgenic lines for each construct continued to resist Foc at 8 months postinoculation. Presence of specific siRNAs derived from the two ihpRNAs in transgenic banana plants was confirmed by Northern blotting and Illumina sequencing of small RNAs derived from the transgenic banana plants. The present study represents an important effort in proving that host-induced post-transcriptional ihpRNA-mediated gene silencing of vital fungal genes can confer efficient resistance against debilitating pathogens in crop plants.
PLOS ONE | 2012
Siddhesh B. Ghag; Upendra K. Singh Shekhawat; T. R. Ganapathi
Antimicrobial peptides are a potent group of defense active molecules that have been utilized in developing resistance against a multitude of plant pathogens. Floral defensins constitute a group of cysteine-rich peptides showing potent growth inhibition of pathogenic filamentous fungi especially Fusarium oxysporum in vitro. Full length genes coding for two Petunia floral defensins, PhDef1 and PhDef2 having unique C- terminal 31 and 27 amino acid long predicted prodomains, were overexpressed in transgenic banana plants using embryogenic cells as explants for Agrobacterium–mediated genetic transformation. High level constitutive expression of these defensins in elite banana cv. Rasthali led to significant resistance against infection of Fusarium oxysporum f. sp. cubense as shown by in vitro and ex vivo bioassay studies. Transgenic banana lines expressing either of the two defensins were clearly less chlorotic and had significantly less infestation and discoloration in the vital corm region of the plant as compared to untransformed controls. Transgenic banana plants expressing high level of full-length PhDef1 and PhDef2 were phenotypically normal and no stunting was observed. In conclusion, our results suggest that high-level constitutive expression of floral defensins having distinctive prodomains is an efficient strategy for development of fungal resistance in economically important fruit crops like banana.
Aob Plants | 2014
Siddhesh B. Ghag; Upendra K. Singh Shekhawat; T. R. Ganapathi
Banana is the fourth most important food commodity of the world and forms the staple food of majority of people in the tropical and subtropical regions. Banana production is severely constrained by Fusarium wilt disease that causes enormous loss. The present study developed transgenic banana plants overexpressing native cell death genes to impart Fusarium wilt resistance. Since banana is predominantly a vegetatively propagated crop, genetic engineering is the most viable option for development of resistance against important diseases of this crop.
PLOS ONE | 2015
Siddhesh B. Ghag; Upendra K. Singh Shekhawat; T. R. Ganapathi
Micro RNAs (miRNAs) are a class of non-coding, short RNAs having important roles in regulation of gene expression. Although plant miRNAs have been studied in detail in some model plants, less is known about these miRNAs in important fruit plants like banana. miRNAs have pivotal roles in plant growth and development, and in responses to diverse biotic and abiotic stress stimuli. Here, we have analyzed the small RNA expression profiles of two different economically significant banana cultivars by using high-throughput sequencing technology. We identified a total of 170 and 244 miRNAs in the two libraries respectively derived from cv. Grand Naine and cv. Rasthali leaves. In addition, several cultivar specific microRNAs along with their putative target transcripts were also detected in our studies. To validate our findings regarding the small RNA profiles, we also undertook overexpression of a common microRNA, MusamiRNA156 in transgenic banana plants. The transgenic plants overexpressing the stem-loop sequence derived from MusamiRNA156 gene were stunted in their growth together with peculiar changes in leaf anatomy. These results provide a foundation for further investigations into important physiological and metabolic pathways operational in banana in general and cultivar specific traits in particular.
International Journal of Pest Management | 2015
Siddhesh B. Ghag; Upendra K. Singh Shekhawat; T. R. Ganapathi
Fusarium oxysporum is a soil borne hyphomycete that causes vascular wilts in several crop plants. A variety of remedial measures such as the use of fungicides, soil amendments and biological antagonists have proved insufficient in controlling F. oxysporum. Ever since it was first reported in banana crop, the only effective control strategy known is planting of resistant cultivars. However, presumably due to the high mutation rates and rapid co-evolution with its host, Fusarium wilt has surmounted host defense barriers and has already begun infecting even the resistant Cavendish varieties that dominate export markets worldwide. Transgenic banana plants showing enhanced resistance to Fusarium wilt have been developed in recent past, but they remain largely confined to the laboratory. The importance of banana as source of food and income in developing countries world over and the need to develop Fusarium wilt tolerant cultivars by novel biotechnological approaches is detailed herein. In this communication, we review the biology and management of Fusarium wilt in banana with the aim of providing the baseline of information to encourage much needed research on integrated management of this destructive banana crop disease problem.
Molecular Biology Reports | 2014
Siddhesh B. Ghag; Upendra K. Singh Shekhawat; T. R. Ganapathi
Fusarium wilt of banana, caused by Fusarium oxysporum f. sp. cubense (Foc), is counted among the most destructive diseases of crop plants in India. In the absence of any credible control measure to manage this disease, development of resistant cultivars is the best option. Somaclonal variations arising out of long term in vitro culture of plant tissues is an important source of genetic variability and the selection of somaclones having desired characteristics is a promising strategy to develop plants with improved characters. In the present study, we isolated a group of somaclonal variants of banana cv. Rasthali which showed efficient resistance towards Foc race 1 infection in repeated bioassays. cDNA-RAPD methodology using 96 decamer primers was used to characterize these somaclonal variants. Among the four differentially amplified bands obtained, one mapping to the coding region of a lipoxygenase gene was confirmed to be down regulated in the somaclones as compared to controls by real-time quantitative RT-PCR. Our results correlated well with earlier studies with lipoxygenase mutants in maize wherein reduced expression of lipoxygenase led to enhanced resistance towards Fusarium infection.
Plant Cell Tissue and Organ Culture | 2015
Siddhesh B. Ghag; Upendra K. Singh Shekhawat; T. R. Ganapathi
Manipulating flavonoid biosynthesis by genetic engineering in economically important crop plants is an emerging area of importance in plant biotechnology. Banana, which is the world most important fruit crop by production volumes, is rich in proanthocyanidins. We hypothesized that by downregulating the critical proanthocyanidin synthesis branch point enzyme, namely anthocyanidin reductase (MusaANR1) using intron-mediated hairpin RNA against its transcript, the levels of the end product of the other branch of phenylpropanoid pathway could be enhanced. Although, the transcript levels of MusaANR1 were successfully downregulated in transgenic banana plants, there was no significant elevation in the levels of anthocyanin in transgenic banana tissues.
GM crops & food | 2016
Siddhesh B. Ghag; Vinayak S. Adki; T. R. Ganapathi; V. A. Bapat
Production of recombinant proteins is primarily established in cultures of mammalian, insect, and bacterial cells. Concurrently, concept of using plants to produce high-value pharmaceuticals such as vaccines, antibodies and dietary proteins have received worldwide attention. Newer technologies for plant transformation such as plastid engineering, agroinfiltration, magnifection and deconstructed viral vectors have been used to enhance protein production in plants along with the inherent advantage of speed, scale and cost of production in plant systems. Production of therapeutic proteins in plants has now a more pragmatic approach when several plant-produced vaccines and antibodies successfully completed Phase I clinical trials in humans and were further scheduled for regulatory approvals to manufacture clinical grade products on large scale safely, efficacious and meeting the quality standards. The main thrust of this review is to summarize the data accumulated over the last two decades and recent development and achievements of the plant derived therapeutics. It also attempts to discuss different strategies employed to increase the production so as to make plants more competitive with the established production systems in this industry.
Plant Cell Tissue and Organ Culture | 2014
Siddhesh B. Ghag; Upendra K. Singh Shekhawat; T. R. Ganapathi
Current Trends in Biotechnology and Pharmacy | 2013
Siddhesh B. Ghag; Upendra K. Singh Shekhawat; T. R. Ganapathi