Utjecaj NaCl na fermentaciju zrelih zelenih rajčica cv. Ailsa Braig u rasolu

The effect of osmotic strength on gene expression and activity of the major enzymes of fermentative metabolism of mature green tomato fruit (Solanum lycopersicum cv. Ailsa Craig) has been studied by exposing fruit to brine containing 0 (water), 5 and 10 % NaCl. The fruits were surface sterilized prior to treatment to prevent the growth of microbes naturally present on the skin of the fruit. Changes in fruit expression of fermentation genes and the activity of the respective enzymes as well as physicochemical quality characteristics (soluble solid content, titratable acidity, pH and firmness) were studied in both fruit and brine for 0.5, 1, 1.5, 2, 3, 7 and 14 days. Discrepancies in responses that resulted from the different salt concentrations were obtained at molecular and quality levels. The complex kinetics of solutes between the fruit and the surrounding solution due to osmotic potential has led to different responses of the tissue to fermentation. Tomato fruit showed cracking soon after storage in water; water-stored fruit had higher titratable acidity, lower soluble solid content, and higher induction of anaerobic metabolism as indicated by the expression or the activity of the fermentation enzymes compared to fruit stored in brine with 5 or 10 % NaCl. No cracking was observed in fruit stored in 5 (isotonic) or 10 % NaCl (hypertonic) brine, though in the latter, signs of dehydration were observed. The presence of salt in brine reduced the intensity of fermentative metabolism as indicated by the lower gene expression and enzyme activity. However, fruit stored in brine with 5 % NaCl survived longer than with 0 or 10 % NaCl. The presence of 5 % NaCl in brine caused mild changes of both the fermentative metabolism and the physicochemical characteristics and prevented fruit deterioration during storage.U radu je ispitan utjecaj osmoze na ekspresiju gena i aktivnost glavnih enzima koji sudjeluju u fermentaciji zrelih zelenih rajčica (Solanum lycopersicum cv. Ailsa Craig), i to uranjanjem plodova u vodu i rasol što sadržava 5 ili 10 % NaCl. Površina je plodova prije obrade sterilizirana da bi se spriječio rast mikroorganizama na pokožici ploda. Analizirani su plodovi rajčice i rasol tijekom 0,5; 1; 1,5; 2; 3; 7 i 14 dana skladištenja, te ispitani ovi parametri: promjena ekspresije gena i aktivnost enzima koji sudjeluju u fermentaciji, te fizikalno-kemijska svojstva plodova (udio topljivih tvari, titracijska kiselost, pH-vrijednost i čvrstoća). Utvrđene su razlike u dobivenim rezultatima, i to na molekularnoj razini te u kakvoći plodova. Zaključeno je da utjecaj fermentacije na tkivo ploda rajčice ovisi o složenoj kinetici prelaska otopljenih tvari iz plodova u otopinu zbog razlike osmotskih tlakova. Skladištenje u vodi uzrokovalo je pucanje plodova koji su imali veću titracijsku kiselost i manji udio topljivih tvari. Ekspresija gena i aktivnost enzima pokazali su da je došlo do povećanja anaerobnog metabolizma u tim plodovima, u usporedbi s onima skladištenim u rasolu. Skladištenje plodova u izotoničnoj otopini (5 % soli) nije uzrokovalo njihovo pucanje, a u hipertoničnoj (10 % soli) otopini nije došlo do pucanja već do dehidracije plodova. Dodatkom soli smanjen je intenzitet fermentacije, što je dovelo do manje ekspresije gena i aktivnosti enzima. Trajnost plodova skladištenih u izotoničnoj otopini bila je veća od onih skladištenih u vodi ili hipertoničnoj otopini. Manja koncentracija soli u otopini nije bitno utjecala na metabolizam fermentacije te kakvoću plodova, a spriječila je njihovo propadanje tijekom skladištenja

HSP90 regulates temperature-dependent seedling growth in Arabidopsis by stabilizing the auxin co-receptor F-box protein TIR1

Recent studies have revealed that a mild increase in environmental temperature stimulates the growth of Arabidopsis seedlings by promoting biosynthesis of the plant hormone auxin. However, little is known about the role of other factors in this process. In this report we show that increased temperature promotes rapid accumulation of the TIR1 auxin co-receptor, an effect that is dependent on the molecular chaperone HSP90. In addition, we show that HSP90 and the co-chaperone SGT1 each interact with TIR1, confirming that TIR1 is an HSP90 client. Inhibition of HSP90 activity results in degradation of TIR1 and interestingly, defects in a range of auxin-mediated growth processes at lower as well as higher temperatures. Our results indicate that HSP90 and SGT1 integrate temperature and auxin signaling in order to regulate plant growth in a changing environment

An enigma in the genetic responses of plants to salt stresses

Soil salinity is one of the main factors restricting crop production throughout the world. Various salt tolerance traits and the genes controlling these traits are responsible for coping with salinity stress in plants. These coping mechanisms include osmotic tolerance, ion exclusion, and tissue tolerance. Plants exposed to salinity stress sense the stress conditions, convey specific stimuli signals, and initiate responses against stress through the activation of tolerance mechanisms that include multiple genes and pathways. Advances in our understanding of the genetic responses of plants to salinity and their connections with yield improvement are essential for attaining sustainable agriculture. Although a wide range of studies have been conducted that demonstrate genetic variations in response to salinity stress, numerous questions need to be answered to fully understand plant tolerance to salt stress. This chapter provides an overview of previous studies on the genetic control of salinity stress in plants, including signaling, tolerance mechanisms, and the genes, pathways, and epigenetic regulators necessary for plant salinity tolerance

Effects of NaCl on Fermentative Metabolism of Mature Green Tomatoes cv. Ailsa Craig in Brine

The effect of osmotic strength on gene expression and activity of the major enzymes of fermentative metabolism of mature green tomato fruit (Solanum lycopersicum cv. Ailsa Craig) has been studied by exposing fruit to brine containing 0 (water), 5 and 10 % NaCl. The fruits were surface sterilized prior to treatment to prevent the growth of microbes naturally present on the skin of the fruit. Changes in fruit expression of fermentation genes and the activity of the respective enzymes as well as physicochemical quality characteristics (soluble solid content, titratable acidity, pH and firmness) were studied in both fruit and brine for 0.5, 1, 1.5, 2, 3, 7 and 14 days. Discrepancies in responses that resulted from the different salt concentrations were obtained at molecular and quality levels. The complex kinetics of solutes between the fruit and the surrounding solution due to osmotic potential has led to different responses of the tissue to fermentation. Tomato fruit showed cracking soon after storage in water; water-stored fruit had higher titratable acidity, lower soluble solid content, and higher induction of anaerobic metabolism as indicated by the expression or the activity of the fermentation enzymes compared to fruit stored in brine with 5 or 10 % NaCl. No cracking was observed in fruit stored in 5 (isotonic) or 10 % NaCl (hypertonic) brine, though in the latter, signs of dehydration were observed. The presence of salt in brine reduced the intensity of fermentative metabolism as indicated by the lower gene expression and enzyme activity. However, fruit stored in brine with 5 % NaCl survived longer than with 0 or 10 % NaCl. The presence of 5 % NaCl in brine caused mild changes of both the fermentative metabolism and the physicochemical characteristics and prevented fruit deterioration during storage

Perspectives on deciphering mechanisms underlying plant heat stress response and thermotolerance

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