Browsing by Author "Kavya Suresh, S S."

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    Variability assessment of fodder cowpea (vigna unguiculata (L.) walp) for mosaic resistance using SSR markers
    (Department of Genetics and Plant Breeding, College of Agriculture,Vellayani, 2025) Kavya Suresh, S S.; Gayathri, G
    The study entitled “Cultivation of Trametes spp. and assessment for laccase activity and cytotoxicity” was conducted at Department of Plant Pathology, College of Agriculture, Vellayani during 2023-2025 with the objectives of standardization of cultivation of Trametes spp. for laccase activity, polysaccharide production and assessment of its cytotoxicity. Survey was conducted at different locations of Thiruvananthapuram, Kollam and Pathanamthitta districts (AEU-1 and 2) for the collection of native Trametes sp. and five mushrooms were obtained viz, M1. M2, M3, M4 and M5. These native mushrooms were isolated and made into pure culture. Cultural characterization of all the isolates (I1. I2, I3, I4 and I5) was carried out using Potato Dextrose Agar (PDA) and observations on mycelial characters, growth rate, and time taken for complete growth in Petri dish (9 cm) were made. Among the isolates I4 was found to be best in terms of the mycelial characters and growth. The molecular characterization was conducted using LSU primers and confirmed the identity of I4 as Trametes sp. (PVO12560). This isolate was selected and compared with Trametes versicolor (DMRO-211). The physiological studies to identify the best media was carried out with I4 and T. versicolor on five different media viz., Potato dextrose agar (PDA), Malt extract agar (MEA), Peptone potato dextrose agar (PPDA), Potato malt agar (PMA) and Czapek Dox agar (CDA). MEA medium recorded the highest mycelial growth rate (1.80 cm day-1) and minimum of 5 days for complete growth in Petri dish for both the isolates. This was followed by PPDA and PMA in I4 and T. versicolor respectively. The optimum temperature for the growth of both the isolates were evaluated at range of 15°C to 35°C in MEA medium. Both the isolates showed optimal growth at 30°C. Higher and lower temperatures (35ºC and 15ºC) were inhibitory for the mycelial growth of I4 while growth was observed in T. versicolor at 15 and 35º C. The cultures of both isolates exhibited rapid growth when incubated at 30ºC. The optimal pH was assessed using MEA medium adjusted to a pH range of 4.5 to 8.0. Isolate I4 demonstrated the highest growth within the pH range of 5.5 to 6.5, whereas T. versicolor showed optimal growth between pH 5.5 and 6.0. Both isolates exhibited growth reduction at pH levels below 5 and above 7. 93 Four different substrates viz., paddy grains, wheat grains, sorghum grains and sawdust (supplemented with 10% rice husk) were evaluated as spawn substrates for the growth and colonization of I4 and T. versicolor. Sorghum grains were observed to be the most suitable substrate, with short spawn run period of 10 days for I4 and 9.75 days for T. versicolor. Substrates suited for sporocarp production of I4 and T. versicolor was evaluated using different media viz., paddy straw, sawdust (amended with 10% rice bran and wheat bran 10%), sawdust + paddy straw (2:3), and spent mushroom substrate. Among these, sawdust amended with 10% rice bran was found to be the efficient substrate for both species. I4 completed spawn run in 38 days and produced 42.7 g of sporocarps, while T. versicolor took 39.5 days for spawn run and yielded 29.5 g. Sawdust supplemented with wheat bran resulted in significantly lower yield. The substrates paddy straw and spent mushroom substrate failed to produce any sporocarp attributed to heavy contamination and poor mycelial colonization. Polysaccharide content was estimated from dried fruiting bodies, where I4 yielded 62.1 % and T. versicolor yielded 56.9 %. GC-MS analysis of mushroom extracts revealed diverse bioactive compounds in both species, including polysaccharides, fatty acids, phenols, and organic compounds. Of these several compound beta D glucopyranose and 1,3,5, cyclohexanetetrol has been reported to possess anticancerous, antioxidant and antimicrobial properties. The isolate I4 exhibited the highest laccase activity during the mycelial stage (64.197 U ml⁻¹), followed by pin head formation stage (52.957 U ml⁻¹) and young fruiting body stage (45.980 U ml⁻¹). T. versicolor exhibited the highest laccase activity at the pin head formation stage (55.863 U ml⁻¹) followed by young fruiting body stage (46.420 U ml⁻¹,) and mycelial stage (41.720 U ml⁻¹). The cytotoxic activity of both isolates was determined using the MTT assay against human colon cancer (HCT-116) cell lines. The ethanolic extract of I4 demonstrated an IC50 value of 371.85 μg mL⁻¹, while T. versicolor showed slightly higher cytotoxicity (308.44 μg mL⁻¹). The present study concluded occurrence
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    Variability assessment of fodder cowpea (vigna unguiculata (L.) walp) for mosaic resistance using SSR markers
    (Department of Genetics and Plant Breeding, College of Agriculture, Vellayani, 2025) Kavya Suresh, S S.
    The research work entitled “Variability assessment of fodder cowpea (Vigna unguiculata (L.) Walp) for mosaic resistance using SSR markers” was conducted at the Department of Genetics and Plant Breeding, College of Agriculture, Vellayani during 2022- 2024 with the objective of analysing the genetic diversity of 45 fodder cowpea accessions for yield, quality, mosaic resistance and validating the reported SSR markers. A pot culture experiment, laid out in a Completely Randomized Design with three replications, was performed to assess response of the accessions to Blackeye cowpea mosaic virus (BlCMV). The 45 fodder cowpea accessions were mechanically inoculated at the cotyledonary leaf stage through sap transmission. Infected plants exhibited characteristic symptoms like vein clearing, leaf mottling, vein banding, blisters on the leaf, leaf distortion, and stunting. Disease scoring was done at 15 and 30 days after inoculation using a 0-5 scale, and disease incidence and vulnerability index values was calculated. Based on disease reaction of fodder cowpea accessions to BlCMV, 45 accessions were classified into different categories where two accessions (TNFC 0926 and C-297) were found to be immune, two (EC101973 and MFC-18-8) were resistant, five were moderately resistant, five moderately susceptible, 28 susceptible and three highly susceptible. The immune accession C-297 exhibited higher phenol content and peroxidase activity compared to the control and susceptible accession. Field screening was conducted from April to June 2024 with 30 selected accessions raised in Randomized Block Design with three replications. The accessions were evaluated for various biometric, qualitative, and biochemical traits, with significant differences observed for all traits except seed yield plant-1. High phenotypic coefficient of variation (PCV) and genotypic coefficient of variation (GCV) were observed for number of primary branches, number of leaves, dry matter yield, green fodder yield, leaf dry weight, stem dry weight and leaf area index (LAI) indicating the influence of environment. High heritability coupled with high genetic advance was observed for crude protein and crude fibre content. Green fodder yield was positively correlated with dry matter yield, leaf dry weight, LAI, stem dry weight, number of leaves, number of primary branches, and crude fibre content. Path coefficient analysis revealed that the number of primary branches had the highest direct effect on green fodder yield, followed by leaf dry weight, while the highest positive indirect effect on green fodder yield was from dry matter yield via leaf dry weight. In genetic divergence analysis using D2 statistics, 30 accessions were grouped into eight clusters. Cluster I, with 23 accessions, was the largest, while clusters II through VIII each contained a single accession. The highest intra-cluster distance was observed in cluster I, and the greatest inter-cluster distance was between clusters III and VIII. Solitary clusters V (EC546491) and VI (MFC-18-8) were identified having higher green fodder yield and quality traits respectively. In the third experiment, genomic DNA from 30 selected fodder cowpea accessions was used for PCR amplification to detect polymorphism between resistant and susceptible accessions. Out of the 10 reported SSR markers for cowpea mosaic virus tested, only two (M80 and MA80) showed polymorphism, successfully distinguishing between the resistant and susceptible accessions. Accessions identified for high green fodder yield (EC546491) and quality traits (MFC-18-8) can be further selected for release as a variety and future genetic improvement programme. Screening for BlCMV in fodder cowpea germplasm identified immune and resistant accessions, which can be utilized to transfer BlCMV resistance into high-yielding fodder cowpea accessions. Additionally, they may serve as tools for genetic diagnostics of BlCMV and for isolating resistance genes via map-based cloning which could potentially be used in genetic transformation of other legume crops to incorporate BlCMV resistance.