The root-endophytic fungus Piriformospora indica (=Serendipita indica) has been revealed for its growth-promoting effects and its capacity to induce resistance in a broad spectrum of host plants. However, the bioefficacy of this fungus had not yet been tested against any pathogen affecting onion (Allium cepa). In this study, the biocontrol potency of P. indica against onion leaf blight, an impacting disease caused by the necrotrophic fungal pathogen Stemphylium vesicarium, was evaluated. First, it was proved that colonisation of onion roots by P. indica was beneficial for plant growth, as it increased leaf development and root biomass. Most relevantly, P. indica was also effective in reducing Stemphylium leaf blight (SLB) severity, as assessed under greenhouse conditions and confirmed in field trials in two consecutive years. These investigations could also provide some insight into the biochemical and molecular changes that treatment with P. indica induces in the main pathways associated with host defence response. It was possible to highlight the protective effect of P. indica colonisation against peroxidative damage, and its role in signalling oxidative stress, by assessing changes in malondialdehyde and H₂O₂ content. It was also showed that treatment with P. indica contributes to modulate the enzymatic activity of superoxide dismutase, catalase, phenylalanine ammonia-lyase and peroxidase, in the course of infection. qPCR-based expression analysis of defence-related genes AcLOX1, AcLOX2, AcPAL1, AcGST, AcCHI, AcWRKY1, and AcWRKY70 provided further indications on P. indica ability to induce onion systemic response. Based on the evidence gathered, this study aims to propose P. indica application as a sustainable tool for improving SLB control, which might not only enhance onion growth performance but also activate defence signalling mechanisms more effectively, involving different pathways.

Onion (Allium cepa L.) is one of the most important vegetable crops due to its diverse culinary and health promoting properties. It is a rich source of dietary phytochemicals such as flavonoids and other antioxidants which enhance the medicinal importance of onion. Onion bulb colour is one of the important quality characters actively targeted in breeding programmes. Onion bulbs with red, white, yellow, golden, pink, chartreuse, etc. colour are available and this variation is due to the mutations in structural and regulatory genes of the flavonoid biosynthesis pathway. The genetics of bulb colour variation is very complex and involves multiple genes and their interactions. Further, these flavonoid compounds and their derivatives play diverse roles in plant development and stress tolerance in plants. Here, we review the biosynthesis of flavonoids, genetics and multiple alleles of genes for onion bulb colour, metabolic engineering, flavonoid in biotic and abiotic stress response and effect of cultural and storage practices on onion flavonoids.

Garlic (Allium sativum L.) is a clonally propagated bulbous crop and can be infected by several viruses under field conditions. A virus complex reduces garlic yield and deteriorates the quality of the produce. In the present study, we aimed to eliminate Onion yellow dwarf virus (OYDV), Garlic common latent virus (GCLV), Shallot latent virus (SLV), and Allexiviruses from the infected crop using combination of meristem culture, thermotherapy, and chemotherapy. In this study, seven different treatments, namely shoot meristem culture, thermotherapy direct culture, chemotherapy direct culture, chemotherapy + meristem culture, thermotherapy + meristem culture, thermotherapy + chemotherapy direct culture, and thermotherapy + chemotherapy + meristem culture (TCMC), were used. Multiplex polymerase chain reaction (PCR) was employed to detect virus elimination, which revealed the percentage of virus-free plants was between 65 and 100%, 55 and 100%, and 13 and 100% in the case of GCLV, SLV, and OYDV, respectively. The in vitro regeneration efficiency was between 66.06 and 98.98%. However, the elimination of Allexiviruses could not be achieved. TCMC was the most effective treatment for eliminating GCLV, SLV, and OYDV from garlic, with 66.06% plant regeneration efficiency. The viral titre of the Allexivirus under all the treatments was monitored using real-time PCR, and the lowest viral load was observed in the TCMC treatment. The present study is the first to report the complete removal of GCLV, SLV, and OYDV from Indian red garlic with the application of thermotherapy coupled with chemotherapy and shoot meristem culture.

The gut microbial community structure of adult Thrips tabaci collected from 10 different agro-climatically diverse locations of India was characterized by using the Illumina MiSeq platform to amplify the V3 region of the 16S rRNA gene of bacteria present in the sampled insects. Analyses were performed to study the bacterial communities associated with Thrips tabaci in India. The complete bacterial metagenome of T. tabaci was comprised of 1662 OTUs of which 62.25% belong to known and 37.7% of unidentified/unknown bacteria. These OTUs constituted 21 bacterial phyla of 276 identified genera. Phylum Proteobacteria was predominant, followed by Actinobacteria, Firmicutes, Bacteroidetes and Cyanobacteria. Additionally, the occurrence of the reproductive endosymbiont, Wolbachia was detected at two locations (0.56%) of the total known OTUs. There is high variation in diversity and species richness among the different locations. Alpha-diversity metrics indicated the higher gut bacterial diversity at Bangalore and lowest at Rahuri whereas higher bacterial species richness at T. tabaci samples from Imphal and lowest at Jhalawar. Beta diversity analyses comparing bacterial communities between the samples showed distinct differences in bacterial community composition of T. tabaci samples from different locations. This paper also constitutes the first record of detailed bacterial communities associated with T. tabaci. The location-wise variation in microbial metagenome profile of T. tabaci suggests that bacterial diversity might be governed by its population genetic structure, environment and habitat.

Allium tuberosum , commonly known as garlic chives, is an underutilized Allium species despite its significant culinary value for its mild garlic flavor and therapeutic potential due to the presence of sulphur-containing compounds with antimicrobial, anti-inflammatory, and antioxidant properties. This study assessed the cultivation potential of A. tuberosum in the non-traditional agro-climatic region of the Western Ghats, focusing on the effects of cultivars and seasonal variations on growth, yield, and quality in two-year field trials. Among the accessions tested, A.tuberosum All-1587 demonstrated the highest yield, producing 157.01 tons of green foliage per hectare. Bright sunshine seasons positively influenced both yield and quality, while the monsoon season induced morphological changes such as increased stem length, reduced leaf width, and decreased stem girth, traits generally considered inferior for market quality. The monsoon also led to increased waste generation, highlighting the need for careful management during this period. Nutritional analysis revealed high concentrations of potassium (5355 mg/kg), phosphorus (691 mg/kg), and sulphur (2484 mg/kg), while biochemical profiling identified bioactive compounds such as flavonoids (3.19 mg/g) and organosulfur compounds, including Allyl Methyl Thiosulfinate (269.00 mg/kg), which contribute to the plant’s notable health benefits. These findings support the suitability of A. tuberosum for year-round cultivation in the Western Ghats and its potential for commercialization, especially in regions with similar climatic conditions.

Grapevine (Vitis vinifera L.), an economically important fruit crop. During field surveys in May 2022, an unusual decline in grapevine was observed in Narayan Tembhi and Wadner Bhairav villages of Nashik district of Maharashtra State in India. Four vineyards (n = ~3000 vines: 3.2 ha) showed 25-30% disease incidence with >70% disease severity (0-5 scale). Diseased vines showed wilting of cordons, and leaves, and "V"-shaped brown to black discoloration in xylem vessels. Ten diseased root samples (three replications) were collected, washed with running tap water for 10 min, cut into 5 × 5 mm pieces, dry blotted, surface sterilized, plated on a PDA medium amended with chloramphenicol (0.2 g/L) and incubated at 26 ± 2°C with a 12-h photoperiod. Hyphal-tip culture method was used to purify three isolates i.e., RI7, RI8, and RI9. Aerial mycelium, loose pinkish-white colonies with orange-white pigmentation. Morphological characteristics were consistent with Fusarium acutatum (Yilmaz et al. 2021). No other pathogens were recovered from roots. Microconidia (n = 100) were aseptate, single-celled (0 septa), oval to allantoid morphology with a size ranging from 5 - 12.5 x 2.5 - 5 μm. Macroconidia (n = 100) were falcate, 1 - 3 septate, with curved and tapering apical cells, with a size ranging from 16.25 - 35 x 2.9 - 4.5 μm. Chlamydospores (n = 50) were round, thick-walled, intercalary, observed in pairs, and single. Molecular characterization of three isolates was carried out based on inter-transcribed spacer (ITS1/ITS4: PQ560056, PQ560065) region, actin (ACT512F/ACT783R: PQ736334), β-tubulin (BT2A/BT2B: PQ736332, PQ736333), and second largest subunit of RNA polymerase II (fRPB2- 5F and fRPB2-7cR: PV232645, PV232646) genes (Carbone and Kohn 1999; Glass and Donaldson 1995; Liu et al., 1999; White et al. 1990). BLASTn sequence analysis revealed 97 - 100% similarity with type strains of Fusarium fujikuroi species complex (FFSC). Multilocus sequence typing (MLST) of three isolates in FUSARIUM-ID database (https://www.fusarium.org/) showed 98.04 to 99.75% identities to F. acutatum (Type strains: CBS 739.97, CBS 401.97, CBS 402.97, CBS 137545, CBS 131573, NRRL 13308). Multigene phylogenetic analyses of concatenated sequence datasets revealed that three isolates closely clustered with Fusarium acutatum based on neighbor-joining (NJ) method through MEGA11. Pathogenicity test (repeated twice) on grape seedlings revealed that about 90% of inoculated plantlets exhibited wilt symptoms (Akgul et al., 2024) except seedlings inoculated with PDA discs with no pathogen. Seedlings were then incubated at 25 ± 2°C at >85% RH under glasshouse. At 45 - 60 days post inoculation (dpi), seedlings exhibited leaf necrosis, shriveled, brown, discolored stems with weak and thin growth, rotten and decayed roots, compared to healthy control. Re-isolation of pathogen as F. acutatum from the roots of inoculated plants fulfilled Koch's postulates by achieving a 95 - 100% isolation rate. Previously, F. oxysporum and F. equiseti have been associated with vascular wilt disease of grapevine in Spain (Astudillo-Calderon et al. 2019). Recently, several Fusarium species have been known to cause various diseases in nurseries and vineyards (Akgul et al. 2024). This is the first evidence of Fusarium acutatum causing root rot and vascular wilt disease in grapevine in India and elsewhere.