Ethno pharmacological Efficiency of Andrographis Paniculata against Tuber Rot Disease of Manihot Esculenta (Cassava)

Cassava is a chief and energy rich carbohydrates food, which might be the reason many parasitic fungi adhere within the plant that causes huge damage to the crop during the post harvesting stage or storage period. In the present study, the ethno-based possible eradication of parasitic fungi was highlighted. Andrographis paniculata Burm. f. Nees and Stachytarpheta indica were chosen for its popular medicinal values and the phytochemical contents were characterized. Its potency showed an inhibitory effects against tuber rot disease causing fungal pathogens viz., Rhizopus sp, Mucor sp., Aspergillus niger, Aspergillus flavus and Fusarium oxysporum in Cassava by disc – diffusion methods. The diameter of the zone of inhibition at various concentrations (2.5, 5, 7.5 and 10 w/v) of leaf extracts was observed with the maximum in A. paniculata (20mm with 10 w/v conc.) against Fusarium oxysporum followed by A. niger (17mm at 10w/v conc.). The preliminary phytochemical screening of Andrographis paniculata revealed the presence of phytoconstituents like alkaloids, flavonoids, phenols, and tannins. In GCMS analysis, Benzene,1,2,3-trimethoxy-5-(2-propenyl)-, Cyclopenta [c] pyran-4-carboxylic acid, 7-methyl-, methyl ester and 9,12,15-Octadecatrienoic acid, methyl ester, (Z, Z, Z)- covered the high areas, that might be responsible or can possess the antifungal activity against Tuber root rot causing fungal pathogens. Furthermore, extensive studies are recommended to characterize each compound in the crude extracts of A. paniculata to enhance or to acclaim remedy for various diseases in plants. This study reveals the acknowledgement of the medicinal plant A. paniculata for its remarkable organic or eco-friendly fungicide potential against cassava tuber rot diseases.

First Report of Post-Harvest Tuber Rot of American Groundnut (Apios americana) Caused by Fusarium acuminatum

Apios americana Medik, commonly known as American groundnut, is a leguminous perennial vine crop native to North America and is cultivated in Japan and Korea (Chu et al. 2019). Its tubers are edible and believed to be very nutritious, especially for women just after childbirth. The tubers also contain secondary metabolites, saponin and genistein, which is good for human health (Ichige et al. 2013). However, the storage of tubers at inappropriate temperatures and humidity levels can cause severe fungal infection, and adversely affect tuber quality. During March and April 2020, a white to pale-orange fungal mycelia were observed on stored American groundnut tubers, with 10 to 15% of seed tubers rotten. Infected tubers were collected, and fungal isolates were isolated on potato dextrose agar (PDA) using the single spore isolation method (Leslie and Summerell 2006). A pure culture (isolate JC20003) was obtained and stored at the Bioenergy Crop Research Institute, NICS, Muan, Republic of Korea. The fungus was cultured on PDA and V8 liquid media for 7 days at 25℃ to observe its morphological characteristics. The length and width of macroconidia ranged from 20.6 to 52.9 μm and 2.9 to 5.1 μm, respectively (n = 30). The microconidia were 8.5 to 14.9 μm and 2.3 to 4.2 μm in length and width, respectively (n = 30). Macroconidia were broadly falcate, strongly septate, 2 to 6 septations with dorsiventral curvature; chlamydospores were formed in chains; and microconidia were fusiform with 0 to 1 septation observed. Genomic DNA of the isolate was extracted using Solgent DNA extraction kit (Solgent, Daejeon, Korea), followed by PCR analysis using the internal transcribed spacer (ITS5/ITS4) and elongation factor (EF-1/EF2) genes (White et al. 1990; O’Donnel 2000). PCR products were sequenced and analyzed to confirm species identity (Yang et al. 2018). These sequences were deposited in GenBank (accession numbers MT703859/ITS and MT731939/EF). BLASTn search analysis showed 100% sequence similarity with Fusarium acuminatum (isolates N-51-1/ITS and WXWH24/EF). Based on morphological and molecular data analysis, the fungus was identified as F. acuminatum (Leslie and Summerell 2006; Marin et al. 2012). Pathogenicity tests were conducted on five tubers inoculated with 5 mm mycelial plugs with three replicates, while a non-mycelial plug served as the control. After 5 days of incubation in plastic containers at 25 °C with high humidity, typical symptoms developed. No symptoms were observed on the control tubers; F. acuminatum was re-isolated from artificially inoculated tubers to complete Koch’s postulates. This is the first report on post-harvest tuber rot caused by F. acuminatum in Apios americana.

Utilization of Endophytes Fungi from Jatropha Leaves (Jatropha curcas L.) Against Fusarium oxysporum Causing Tuber Rot Disease Onion (Allium cepa var. Ascalonicum (L.) Backer)

Tuber rot is one of the important diseases in onion caused by Fusarium oxysporum. Endophytes are biological agents that are currently widely used in controlling plant diseases. Excessive use of pesticides and continuously has shown negative impacts such as resurgence, resistance to pests and pathogens, and the death of natural enemies. Currently, pests and pathogens control effort are directed at the utilization of natural enemies or better known as biological control. Endophyte is a microorganism that grows in plant tissues without causing symptoms. Endophytes allegedly capable of producing a variety of phytochemical compounds generated by their host. The leaves of Jatropha (Jatropha curcas L.) is one part of the plant that contains secondary metabolites.Phytochemical tests on the Jatropha show that Jatropha contains alkaloids, flavonoids, and saponins that are an antimicrobial potential of plant-pathogen control agents. This study aimed to determine the effect of some Endophytes isolates and their impact on the growth of F. oxysporum in vitro in onion.Exploration (endophyte isolation from Jatropha healthy leaves) and observation (antagonist test of Endophytes of the Jatropha leaves) method used in this study was a Completely Randomized Design (CRD) with a single factor (10 treatment) repeated three times. There were 14 endophytes isolated from Jatropha leaves with a growth ratio of 4.5 cm/2 days. The best treatment to inhibit the growth of F. oxysporum in vitro is Jc5, Jc8, Jc10.