Effects of extracellular K+ on grapevine membrane potential as influenced by the antiviral mycophenolic acid. An electrophysiological study

Mycophenolic acid (MPA) is an effective antiviral drug in plants, and its action in modulating the activity of KATP channels is already known in animals. In the present work, an electrophysiological study was carried out to investigate MPA effects on plant K+ channels, through the measurement of trans-plasma membrane potential in samples of Vitis vinifera cv. Sangiovese treated with extracellular K+. Tests confirmed that the administration of MPA (in preincubated samples or in those maintained under chemical treatment) can reduce the membrane depolarization induced by K+. However, MPA-induced alteration in membrane potential was sensitive to the KATP channel opener diazoxide, as well to treatments with guanosine. This result confirms the effectiveness of MPA in influencing KATP channel activity as well as inhibiting activity of the inward-rectifier potassium ion channel which could be mediated by guanosine depletion induced by MPA

RFID microchip internal implants: effects on grapevine histology

SUMMARY Interesting applications for traceability in agriculture have recently been developed using radiofrequency identification (RFID) technology. A preliminary report of survival and growth in grapevine suggested pith not only as optimal microchip localization within the plant, but only continuous monitoring of performances, supported by histological observation of tissues around microchips, can validate this approach as a long-term strategy for grapevine identification. In this study, histological assays of grapevine plants are reported, considering different strategies in RFID marking. Microchip insertion after direct drilling of pith from a distal cut on rootstocks did not show any differences in tissue status compared to control, and this can be adequately correlated to an absence of effect in plant growth. Conversely, a “U” cut performed laterally on the rootstock to insert the microchip, which involved tissues from bark to pith, caused development of callus tissues, restoring transversal continuity, but with a partial loss of functionality in terms of open vessels. This phenomenon can be considered permanent damage to plant vascular function, but with limited extension

Radiofrequency applications in grapevine: From vineyard to web

SUMMARY An experimental trial was commenced in January 2007 of a traceability system for grapevine plants produced in a nursery and for electronic management of vineyards. The main objective was producing grafted cuttings using common nursery procedures, but in which were internally installed Radio Frequency Identification chips. The trial used five common Tuscan grapevine clones. The modified plants were indistinguishable from unmarked plants, and will maintain this electronic feature throughout their life. The marked plants can be easily monitored, and will be able to supply various information, including identity, growth parameters, susceptibility to biotic stress factors, and productivity. All information is available by a website accessing a database, guaranteeing that users (e.g. nursery workers, grapevine growers, and plant pathologists) can use online access to retrieve information on every marked plant

Effect of mycophenolic acid on trans-plasma membrane electron transport and electric potential in virus-infected plant tissue

none4Mycophenolic acid (MPA) is an inosine monophosphate dehydrogenase inhibitor whose antiviral mechanism of action is supposed to interfere with NAD(+)/NADH conversion. Its effects on trans-plasma membrane electron transport (t-PMET) and on trans-plasma membrane electric potential (t-PMEP), which are involved in the NAD(+)/NADH conversion, were investigated using microelectrochemical techniques in tobacco plants infected by Cucumber mosaic virus. In these tests, ferricyanide (Fe(3+)) was used as electron acceptor in assays performed with intact cells; ferricyanide is converted to ferrocyanide (Fe(2+)) by one-electron reduction, and the rate of this reduction can be monitored in order to investigate the effects on t-PMET or t-PMEP. Considering tests on t-PMEP, MPA treatment of samples induced membrane depolarization and this effect was greater in healthy samples compared to infected ones. In any case, complete repolarization was achieved, indicating no irreversible damage to the membrane due to MPA administration. Moreover, in samples pre-treated with MPA, the extent of depolarization caused by Fe(3+) administration was lower than in samples without pre-treatment but the MPA effect was not related to virus infection. With regard to tests on t-PMET, MPA caused a reduction in Fe(3+)/Fe(2+) conversion compared to untreated plants. However, infected samples were less sensitive to MPA treatment, which may be due to the concurrent entry of MPA within the symplast that, as indicated by t-PMEP tests, was lower in infected samples. In conclusion, MPA interferes with membrane activity linked to NAD(+)/NADH conversion, acting differently in infected or healthy samples during drug uptake by cells.Rinaldelli, Enrico; Panattoni, Alessandra; Luvisi, Andrea; Triolo, EnricoRinaldelli, Enrico; Panattoni, Alessandra; Luvisi, Andrea; Triolo, Enric