Grafting is used in vegetable production to improve plant vigour and tolerance to soil-borne diseases, yet the biological properties of the graft union remain poorly understood. Here, we investigated culturable bacteria associated with tomato (Solanum lycopersicum L.) graft unions. Bacterial populations reached 105-107 colony-forming units per gram of fresh weight (CFU g-1 FW) in graft union tissues. However, no culturable bacteria were detected from non-grafted stem samples collected from the graft union equivalent position at the corresponding sampling time (i.e. 8 days after grafting in grafted plants). The predominant bacterial genera isolated from graft unions were Microbacterium and Sphingomonas. All isolates tested negative for the hypersensitive reaction in tobacco, indicating their non-pathogenic nature. The isolates exhibited functional traits, including effects on seedling growth, phosphate solubilisation, production or degradation of N-acyl-homoserine lactones, and antibacterial activity against Ralstonia pseudosolanacearum. In addition, isolates were associated with reduced symptom development of bacterial wilt in tomato seedlings under controlled conditions. These results suggest that graft unions may provide a biologically active environment associated with the recovery of diverse culturable bacterial communities. Our findings provide insight into bacteria associated with tomato graft unions and their potential functional properties relevant to horticultural production.
Anthracnose of mango caused by Colletotrichum spp. results in quality loss, reduced shelf life, and diminished market value. Despite its economic impact, the molecular basis of mango-Colletotrichum asianum interactions remains largely unclear. This study assessed the antifungal activity of salicylic acid (SA) against C. asianum and explored its potential mechanisms. SA inhibited mycelial growth in a concentration-dependent manner, with complete arrest of spore germination at concentrations >= 2 mM. Postharvest application of 2 mM SA significantly suppressed lesion development in the fruits of 'Alphonso' and 'Banganapalli' cultivars, compared with untreated controls. Gene expression profiling at 2 mM SA was conducted in 'Gomavu' (moderately resistant) and 'Banganapalli' (susceptible) cultivars. In 'Gomavu', MRNBS-11 transcripts were markedly elevated at 6 and 12 h post-inoculation, indicating early pathogen recognition and activation of defence signalling. Additionally, SA treatment induced the expression of pathogenesis-related (PR) proteins (PR4, PR1A) and defence-related enzymes (Phenylalanine ammonia-lyase, Peroxidase), highlighting their role in restricting C. asianum infection. These findings demonstrate the potential of SA as a postharvest treatment for managing mango anthracnose and provide novel insights into the genetic basis of resistance. Further validation through field trials, and exploration of genetic improvements is recommended to strengthen disease management strategies.
The study assessed the effectiveness of bagging in terms of carbon emissions, energy use, fruit quality, and pest incidence in mango (Mangifera indica L.). Fruits of Dashehri and Amrapali were bagged with double-layered brown paper bags after 4-5 weeks of fruit set. Bagging markedly reduced the frequency of pesticide applications (<0.2 sprays) compared with non-bagged fruits (>3 sprays), leading to a significant decline in carbon emissions (161-208 kg CE ha(-1)) and energy input (120-145 MJ ha(-1)), compared to carbon emissions (1200-1400 kg CE ha(-1)) and energy input (2800-3700 MJ ha(-1)) for non-bagged fruit. High proportion of unmarketable fruits emerged as the largest contributor (61%) to carbon emissions in unbagged fruits, followed by pesticide use and machinery operations. Significant improvement in skin colour attributes and shelf life (6.79-7.86 days) was observed, along with higher fruit firmness and a substantial reduction in sunburn incidence (0.17-0.24%). Fruit bagging significantly increased the proportion of marketable yield (93-95%) and improved the overall market value of the fruits. However, it slightly reduced the soluble solids content and sugar concentration. The incidence of anthracnose (0.37-0.40%), shoulder browning (0.08-0.42%) and fruit fly infestation was almost eliminated in bagged fruits.
Chrysanthemum white rust, caused by Puccinia horiana, poses a serious threat to chrysanthemum (Chrysanthemum morifolium) production. The development of resistant cultivars is of great interest to breeders. Owing to the polyploid nature and complex inheritance patterns of chrysanthemum, efficiently utilising resistance genes in breeding programmes has been challenging. However, in recent years, DNA markers linked to resistance have been developed. Although multiple resistance sources have already been identified in chrysanthemum, this study aimed to discover additional resistance genes. We identified two previously unknown resistance genetic loci, Phr3 and Phr4. The genetic locus Phr3 conferred resistance to a relatively broad range of races. Although the resistance spectrum conferred by Phr4 was limited, it represents the resistance found in the important Japanese standard-type cultivar 'Jimba' and is expected to be useful in the development of progeny cultivars. We developed DNA markers linked to Phr3 and Phr4, enabling marker-assisted selection and gene pyramiding for rust resistance.
