Management of Phytophthora parasitica causing gummosis in citrus using biogenic copper oxide nanoparticles.

AIM: The main aim of the present study was to develop nanotechnology-based solutions for the management of a fungus, Phytophthora parasitica causing gummosis in citrus. METHODS AND RESULTS: Biogenic copper nanoparticles (CuONPs) were synthesized using two different biocontrol agents, Pseudomonas fluorescens and Trichoderma viride and characterized using different analytical techniques. Furthermore, in vitro (at the concentrations of 10, 15, 30, 50, 70, 100 and 150 mg/L) and in vivo (at the concentration of 100 mg/L) activities of these nanoparticles were evaluated for their antifungal efficacy against P. parasitica. The results obtained confirmed the synthesis of irregular-shaped CuONPs having a size in the range 40-100 nm in case of P. fluorescens, whereas, spherical CuONPs in the size range 20-80 were recorded in case of T. viride. As far as the in vitro antifungal efficacies of both these CuONPs is concerned, the maximum percent growth inhibition was observed in case of CuONPs synthesized from T. viride compared to CuONPs from P. fluorescens. However, in case of in vivo antifungal efficacies, CuONPs synthesized from T. viride showed the activity significantly higher than the conventionally used Bordeaux mixture. CONCLUSIONS: It can be concluded that biosynthesized CuONPs can be effectively used as a potential fungicide against P. parasitica. SIGNIFICANCE AND IMPACT OF THE STUDY: The application of nanoparticles having antifungal activities can be used as alternative fungicides to the conventional chemical fungicides. It has the potential to revolutionize the existing management strategies available for plant pathogenic fungi.

Transcriptomic signature reveals mechanism of flower bud distortion in witches'-broom disease of soybean (Glycine max).

BACKGROUND: Soybean (Glycine max L. Merril) crop is major source of edible oil and protein for human and animals besides its various industrial uses including biofuels. Phytoplasma induced floral bud distortion syndrome (FBD), also known as witches' broom syndrome (WBS) has been one of the major biotic stresses adversely affecting its productivity. Transcriptomic approach can be used for knowledge discovery of this disease manifestation by morpho-physiological key pathways. RESULTS: We report transcriptomic study using Illumina HiSeq NGS data of FBD in soybean, revealing 17,454 differentially expressed genes, 5561 transcription factors, 139 pathways and 176,029 genic region putative markers single sequence repeats, single nucleotide polymorphism and Insertion Deletion. Roles of PmbA, Zn-dependent protease, SAP family and auxin responsive system are described revealing mechanism of flower bud distortion having abnormalities in pollen, stigma development. Validation of 10 randomly selected genes was done by qPCR. Our findings describe the basic mechanism of FBD disease, right from sensing of phytoplasma infection by host plant triggering molecular signalling leading to mobilization of carbohydrate and protein, phyllody, abnormal pollen development, improved colonization of insect in host plants to spread the disease. Study reveals how phytoplasma hijacks metabolic machinery of soybean manifesting FBD. CONCLUSIONS: This is the first report of transcriptomic signature of FBD or WBS disease of soybean revealing morphological and metabolic changes which attracts insect for spread of disease. All the genic region putative markers may be used as genomic resource for variety improvement and new agro-chemical development for disease control to enhance soybean productivity.

Cytological behaviour of floral organs and in silico characterization of differentially expressed transcript-derived fragments associated with 'floral bud distortion' in soybean.

An attempt was made to understand the 'floral bud distortion' (FBD), an unexplored disorder prevailing in soybean. Cytological behaviour of floral reproductive organs and in silico characterization of differentially expressed transcript-derived fragments (TDFs) in symptomatic and asymptomatic soybean plants were carried out. Pollens in asymptomatic plants do not have defects in number, size, shape and function. However, in symptomatic plant, pollens were found nonviable, abnormal in shape and with reduced germination ability. Here, we employed a computational approach, exploring invaluable resources. The tissue-specific transcript profile of symptomatic and asymptomatic sources was compared to determine differentially expressed TDFs associated with FBD to improve its basic understanding. A total of 60 decamer primers produced 197 scorable amplicons, ranged 162-1130 bp, of which 171 were monomorphic and 26 were differentially regulated. Reproducible TDFs were sequenced and characterized for their homology analysis, annotation, protein-protein interaction, subcellular localization and their physical mapping. Homology-based annotation of TDFs in soybean revealed presence of two characterized and seven uncharacterized hits. Annotation of characterized sequences showed presence of genes, namely auxin response factor 9 (ARF9) and forkhead-associated (FHA) domain, which are directly involved in plant development through various pathways, such as hormonal regulation, plant morphology, embryogenesis and DNA repair.