Sodium Selenate: An Environmental-Friendly Means to Control Tomato Bacterial Speck Disease

Abstract

Selenium (Se) is a micronutrient which plays a beneficial role in plants. Its adsorption at low doses can stimulate plant growth and enhance the plant’s capacity to respond to abiotic stresses, such as salinity, drought, cold and hot temperature, probably due to its antioxidant properties. Here, the effect of selenium supplied in soil-drench treatments as sodium selenate (Na2SeO4) at the dose of 4 mg L−1 (21.17 µM) per plant was studied on tomato (Solanum lycopersicum L.; cv. Rio Grande) against Pseudomonas syringae pv. tomato (Pst), the causal agent of tomato bacterial speck. Sodium selenate treated tomato plants challenged with Pst showed a reduction in disease severity expressed as percentage of diseased area and number of lesions per leaf. Furthermore, Pst bacterial cells were unable to proliferate in treated tomato plants. The effect of sodium selenate against Pst was also assessed in vitro, demonstrating that the growth of the bacterium was affected in a dose-dependent manner (EC50 = 42 ppm). It is notable that in tomato plants treated with sodium selenate at the above reported dose, a marked callose deposition was observed as well as the expression of the salicylic-acid-responsive tomato ‘pathogenesis-related protein 1b1’ (PR1b1) but not of the jasmonate-mediated ‘proteinase inhibitor 2’ (PIN2) genes. Induced defence responses and direct antimicrobial activity protect treated tomato plants against Pst attacks, suggesting the potential of sodium selanate as an environmentally friendly and effective bacterial control means. Moreover, the increased Se content in treated tomatoes offers an effective approach to reduce Se deficiency problems in human diets.

Greater than the sum of their parts: an overview of the AvrRps4 effector family

“…As summarized in this review, the presence of xopO and xopAK within the same strains of Xanthomonas, hopK1 association with transposable elements (Peters et al, 2014;Orfei et al, 2023), and avrRps4 and hopK1's occasional location on plasmids (Kim et al, 1998;Chang et al, 2005;Orfei et al, 2023) seem to indicate that our chimeric effectors may have been formed in a Xanthomonas melting pot and then shared with bacteria inhabiting a similar niche, such as Pseudomonas, via horizontal gene transfer (HGT). HGT has been implicated in the evolution of Pseudomonas (Kim et al, 1998;Rohmer et al, 2004;Dillon et al, 2019) and Xanthomonas (Merda et al, 2017;Ruh et al, 2017;Chen et al, 2018) pathogenicity in the past, though not specifically for the AvrRps4 effector family.…”

“…In Pto DC3000, the hopK1 gene is located on the chromosome and is encoded in a 24 kb Tn6022-like element, but in other strains hopK1 may occur on a plasmid (Li et al, 2014;Peters et al, 2014). In the case of Pto DAPP-PG 215, hopK1 is borne on p107, a small plasmid which possesses two prophage regions and some precursors for coronatine production in addition to the effector (Orfei et al, 2023).…”

Nano-selenium enhances melon resistance to Podosphaera xanthii by enhancing the antioxidant capacity and promoting alterations in the polyamine, phenylpropanoid and hormone signaling pathways

“…Selenium (Se) compounds are known to have beneficial effects on plant resistance to pathogens [ 14 ], which may occur through a variety of mechanisms in different species, including the enhancement of reactive oxygen species (ROS) scavenging [ 15 ], defensive callose deposition [ 16 ] and the upregulation of antifungal pathways [ 17 ]. The application of Se to soil has also been reported to increase the relative abundance of beneficial microorganisms, with a decrease in pathogenic fungi [ 14 ].…”

A CNNA-Based Lightweight Multi-Scale Tomato Pest and Disease Classification Method

“…However, the growth process of tomato plants is often plagued by a variety of pests and diseases, which seriously hinder the development of the tomato growing industry and affect farmers. Effective and accurate identification of tomato pests and diseases is an important tool for their management and an important prerequisite for improving tomato production [1,2]. Traditional tomato disease identification is typically carried out exclusively by experts or technicians due to their high accuracy, but the methods are not widely applicable due to their time-consuming, costly, and inefficient nature [3].…”