Effects of Selenium Uptake by Tomato Plants on Senescence, Fruit Ripening and Ethylene Evolution

ABSTRACT The fate of salmonellae applied to tomato plants was investigated. Five Salmonella serotypes were used to inoculate tomato plants before and after fruits set, either by injecting stems with inoculum or brushing flowers with it. Ripe tomato fruits were subjected to microbiological analysis. Peptone wash water, homogenates of stem scar tissues, and homogenates of fruit pulp were serially diluted and plated on bismuth sulfite agar before and after enrichment. Presumptive Salmonella colonies were confirmed by serological tests, PCR assay using HILA2 primers, and enterobacterial repetitive intergenic consensus PCR. Of 30 tomatoes harvested from inoculated plants, 11 (37%) were positive forSalmonella. Of the Salmonella-positive tomatoes, 43 and 40%, respectively, were from plants receiving stem inoculation before and after flower set. Two of eight tomatoes produced from inoculated flowers contained Salmonella. Higher percentages of surface (82%) and stem scar tissue (73%) samples, compared to pulp of Salmonella-positive tomatoes (55%), harbored the pathogen. Of the five serotypes in the inoculum, Montevideo was the most persistent, being isolated from tomatoes 49 days after inoculation, and Poona was the most dominant, being present in 5 of 11 Salmonella-positive tomatoes. Results suggest that Salmonella cells survive in or on tomato fruits from the time of inoculation at flowering through fruit ripening. Tomato stems and flowers are possible sites at whichSalmonella may attach and remain viable during fruit development, thus serving as routes or reservoirs for contaminating ripened fruit.

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Tomato Protein Phosphatase 2C (SlPP2C3) influences fruit ripening onset and fruit glossiness

Journal of Experimental Botany ◽

10.1093/jxb/eraa593 ◽

2020 ◽

Author(s):

Bin Liang ◽

Yufei Sun ◽

Juan Wang ◽

Yu Zheng ◽

Wenbo Zhang ◽

...

Keyword(s):

Fruit Ripening ◽

Vital Role ◽

Negative Regulator ◽

Rna Seq ◽

Tomato Plants ◽

Enhanced Sensitivity ◽

Physiological Processes ◽

Significant Difference ◽

Epidermis Structure

Abstract Abscisic acid (ABA) plays a vital role in coordinating physiological processes during fresh fruit ripening. Binding of ABA to receptors facilitates the interaction and inhibition of type 2C phosphatase (PP2C) co-receptors. However, the exact mechanism of PP2C during fruit ripening is unclear. In this study, we determined the role of tomato ABA co-receptor type 2C phosphatase SlPP2C3, a negative regulator of ABA signalling and fruit ripening. SlPP2C3 selectively interacted with monomeric ABA receptors and SlSnRK2.8 kinase in both yeast and tobacco epidermal cells. Expression of SlPP2C3 was ABA-inducible, which was negatively correlated with fruit ripening. Tomato plants with suppressed SlPP2C3 expression exhibited enhanced sensitivity to ABA, while plants over-expressing SlPP2C3 were less sensitive to ABA. Importantly, lack of SlPP2C3 expression accelerated fruit ripening onset and affected fruit glossiness by altering the outer epidermis structure. There was a significant difference in expression of cuticle-related genes in pericarp between wild-type and SlPP2C3 suppressed lines based on RNA sequencing (RNA-seq) analysis. Taken together, our findings demonstrate that SlPP2C3 plays an important role in the regulation of fruit ripening and fruit glossiness in tomato.

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Identification of α-Tomatine 23-Hydroxylase Involved in the Detoxification of a Bitter Glycoalkaloid

Plant and Cell Physiology ◽

10.1093/pcp/pcz224 ◽

2019 ◽

Vol 61 (1) ◽

pp. 21-28 ◽

Cited By ~ 2

Author(s):

Masaru Nakayasu ◽

Ryota Akiyama ◽

Midori Kobayashi ◽

Hyoung Jae Lee ◽

Takashi Kawasaki ◽

...

Keyword(s):

Fruit Ripening ◽

Tomato Fruit ◽

Transgenic Tomato ◽

Metabolic Enzyme ◽

Gene Encoding ◽

Tomato Plants ◽

Tomato Fruit Ripening ◽

Transgenic Tomato Plants ◽

Key Enzyme ◽

Esculeoside A

Abstract Tomato plants (Solanum lycopersicum) contain steroidal glycoalkaloid α-tomatine, which functions as a chemical barrier to pathogens and predators. α-Tomatine accumulates in all tissues and at particularly high levels in leaves and immature green fruits. The compound is toxic and causes a bitter taste, but its presence decreases through metabolic conversion to nontoxic esculeoside A during fruit ripening. This study identifies the gene encoding a 23-hydroxylase of α-tomatine, which is a key to this process. Some 2-oxoglutarate-dependent dioxygenases were selected as candidates for the metabolic enzyme, and Solyc02g062460, designated Sl23DOX, was found to encode α-tomatine 23-hydroxylase. Biochemical analysis of the recombinant Sl23DOX protein demonstrated that it catalyzes the 23-hydroxylation of α-tomatine and the product spontaneously isomerizes to neorickiioside B, which is an intermediate in α-tomatine metabolism that appears during ripening. Leaves of transgenic tomato plants overexpressing Sl23DOX accumulated not only neorickiioside B but also another intermediate, lycoperoside C (23-O-acetylated neorickiioside B). Furthermore, the ripe fruits of Sl23DOX-silenced transgenic tomato plants contained lower levels of esculeoside A but substantially accumulated α-tomatine. Thus, Sl23DOX functions as α-tomatine 23-hydroxylase during the metabolic processing of toxic α-tomatine in tomato fruit ripening and is a key enzyme in the domestication of cultivated tomatoes.

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Herbicidal Actions of Root-Applied Glufosinate Ammonium on Tomato Plants

Journal of the American Society for Horticultural Science ◽

10.21273/jashs.127.2.200 ◽

2002 ◽

Vol 127 (2) ◽

pp. 200-204 ◽

Cited By ~ 6

Author(s):

Wenqi You ◽

Allen V. Barker

Keyword(s):

Time Course ◽

Initial Rate ◽

Plant Responses ◽

Fresh Weight ◽

Ethylene Evolution ◽

Tomato Plants ◽

Fresh Weight Basis ◽

Glufosinate Ammonium ◽

Time Course Experiment ◽

Slight Inhibition

The herbicidal action of foliar applications of glufosinate-ammonium (GLA) is due to toxic accumulation of unassimilated NH4+ in leaves; however, the effects of root-applied GLA on NH4+ accumulation and plant growth are unknown. In a dose-response hydroponics experiment, tomato (Lycopersicon esculentum Mill.) plants were grown in nitrate-based solutions with GLA added at 0, 6, 12, 25, or 50 mg·L-1. To observe plant responses to an exogenous NH4+ source with herbicide-induced responses, plants were grown in an NH4+-based solution without GLA addition. At 6 days after treatment (DAT), GLA in solution at 25 mg·L-1 produced partial leaf wilting, chlorosis, and necrosis of foliage, and at 50 mg·L-1, plants were fully wilted and necrotic. Ammonium (NH4+-N) concentration in shoots at 6 DAT increased from 0 to 6 mg·g-1 fresh weight with increasing GLA in the nutrient solution. Ethylene evolution doubled (from 4 to 8 nL·g-1·h-1, fresh weight) with increases in GLA from 0 to 25 mg·L-1 but declined with apparent plant death with GLA at 50 mg·L-1. Other treatments, including NH4+ nutrition, did not induce toxicity symptoms in leaves or give increases in NH4+ accumulation or ethylene evolution during the 6 days of the experiment. In a time-course experiment, tomato plants treated with GLA at 25 mg·L-1 were chlorotic at 4 DAT. Ethylene evolution (fresh weight basis) rose from an initial rate of 2.6 nL·g-1·h-1 to 8.3 nL·g-1·h-1 after 4 days. At 9 DAT, all plants receiving this treatment died. In the time-course experiment, an exogenous NH4+ treatment caused a slight inhibition in shoot fresh weight relative to NO3- nutrition with no GLA but caused no visible symptoms and only slight enhancements in NH4+ accumulation and ethylene evolution over the 9-day period. Following GLA treatment, NH4+ accumulated in the shoots and increased sharply with time, whereas exogenous NH4+ led to NH4+ accumulation primarily in roots. Results suggest that GLA was absorbed by roots and translocated to shoots, where it initiated accumulation of NH4+ and ethylene evolution as indications of herbicidal action. Chemical name used: glufosinate-ammonium, GLA.

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537 Use of Lysophoshatidylethanolamine (LPE), a Natural Lipid, to Prevent Damaging Effects of Ethephon on Tomato Plants

HortScience ◽

10.21273/hortsci.34.3.538d ◽

1999 ◽

Vol 34 (3) ◽

pp. 538D-538

Author(s):

Mustafa Ozgen ◽

Jiwan P. Palta

Keyword(s):

Chlorophyll Content ◽

Fruit Ripening ◽

Tomato Fruit ◽

Parallel Study ◽

Tomato Plants ◽

Foliar Damage ◽

Ethephon Treatment ◽

Natural Lipid ◽

Potential Use ◽

Damaging Effects

Ethephon [2-(chloroethyl) phoshonic acid] is used widely to maximize the yield of ripe tomato fruit. However, ethephon causes rapid and extensive defoliation, overripening, and promotes sunscald damage to the fruit. Recent studies from our laboratory have provided evidence that lysophoshatidylethanolamine (LPE) can reduce leaf senescence. We investigated the potential use of LPE to reduce damaging effect of ethephon on tomato foliage. Three-month-old tomato plants (variety Mountain Spring) grown in greenhouse conditions were sprayed with 200 ppm LPE (with 3% ethanol) at 6 and 24 h before ethephon treatment. After 8 days, plants treated with ethephon alone showed about 80% foliar damage while plant treated with LPE before ethephon treatment showed about 25% foliar damage. In a parallel study, LPE together with ethephon was found to maintain three to four times greater chlorophyll content in the leaves compared to ethephon alone. Treatments of LPE did not reduce the fruit ripening response by ethephon. Both sources of LPE were effective in preventing damaging effects of ethephon on the foliage. These results suggest that LPE treatments 6 and 24 h before ethephon application can prevent damaging effects of ethephon on foliage while allowing the acceleration of fruit ripening.

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