Effect of the Enhanced Production of Chlorophyll b on the Light Acclimation of Tomato.

Tomato (Solanum lycopersicum Mill.) is one of the widely cultured vegetables under protected cultivation, in which insufficient light is one of the major factors that limit its growth, yield, and quality. Chlorophyll b (Chl b) is exclusively present in the light-harvesting complex (LHC) of photosystems, while its synthesis is strictly regulated in response to light conditions in order to control the antenna size. Chlorophyllide a oxygenase (CAO) is the sole enzyme that converts Chl a to Chl b for Chl b biosynthesis. Previous studies have shown that overexpressing CAO without the regulating domain (A domain) in Arabidopsis overproduced Chl b. However, the growth characteristics of the Chl b overproduced plants under different light environmental conditions are not well studied. Considering tomatoes are light-loving plants and sensitive to low light stress, this study aimed to uncover the growth character of tomatoes with enhanced production of Chl b. The A domain deleted Arabidopsis CAO fused with the FLAG tag (BCF) was overexpressed in tomatoes. The BCF overexpressed plants accumulated a significantly higher Chl b content, resulting in a significantly lower Chl a/b ratio than WT. Additionally, BCF plants possessed a lower maximal photochemical efficiency of photosystem II (Fv/Fm) and anthocyanin content than WT plants. The growth rate of BCF plants was significantly faster than WT plants under low-light (LL) conditions with light intensity at 50-70 µmol photons m-2 s-1, while BCF plants grew slower than WT plants under high-light (HL) conditions. Our results revealed that Chl b overproduced tomato plants could better adapt to LL conditions by absorbing more light for photosynthesis but adapt poorly to excess light conditions by accumulating more ROS and fewer anthocyanins. Enhanced production of Chl b is able to improve the growth rate of tomatoes that are grown under LL conditions, indicating the prospect of employing Chl b overproduced light-loving crops and ornamental plants for protected or indoor cultivation.

In vitro studies on the cytotoxicity, elastase, and tyrosinase inhibitory activities of tomato (Solanum lycopersicum Mill.) extract.

Tomatoes (Solanum lycopersicum Mill.), a common vegetable in Indonesia, contain high levels of lycopene, which is good for the body. This research further investigates the activity of polar and nonpolar fractions of tomatoes as elastase and tyrosinase inhibitory, and cytotoxic agents. The extraction procedure used is maceration, fractionation through liquid-liquid fractionation, purification of phytochemical substances is achieved through the application of thin layer chromatography. Elastase and tyrosinase inhibitory activity was analyzed using spectrophotometry and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide cytotoxic assay. The result showed that the extract yield was 0.004%. The percentage of polar fraction from the extract was 2.58%, while the nonpolar fraction was 0.69%. The elastase inhibitory activity of polar and nonpolar fractions of tomato extract is 87.21% ± 7.57% and 73.12% ± 7.44%, respectively, The elastase inhibitory activity of polar and nonpolar fractions of tomato extract is 87.21% ± 7.57% and 73.12% ± 7.44%, respectively. The fractions had higher the anti-elastase activity than the positive control quercetin (65.97% ± 3.00%). The tyrosinase inhibitory activity of polar and nonpolar fractions of tomato extract is 23.71% ± 7.91% and 41.16% ± 5.41% (kojic acid as standard is 65.07% ± 0.86%), respectively. The IC50 of the cytotoxic assay to NIH 3T3 mouse embryonic fibroblast cells of the polar and nonpolar fraction of tomato extract is 1820.90 µg/mL and 1643.86 µg/mL, respectively.

Effect of Organic Residues as Fertilizer on Postharvest Quality of Cherry Tomatoes

Abstract Composting of domestic residues to replace cattle manure was evaluated as a fertilization option for the cherry tomato crop. Two sources of organic compounds (CO) were used to prepare compost piles: Domestic residues (DR) and bovine manure (BM), used in 5 proportions (CO1 = 15% DR + 15% BM, CO2 = 10% DR + 20% BM, CO3 = 20% DR + 10% BM, CO4 = 30% BM (control) and CO5 = 30% DR). To compost the compost piles, the organic waste (carbon source) was mixed with remnants of tree pruning (filler) from the urban cleaning service in a ratio of 1: 3. After 90 days, the compost from each matured pile was mixed with 1: 1 coconut fiber substrate and filled into 15 L plastic bags where the cherry tomato plants were grown. The experiment was conducted in a greenhouse using the experimental design of randomized blocks with 5 treatments and 5 replicates (6 fruits per sample). The organic fertilization in the proportions of manure and food residue did not provide statistically significant differences in soluble solids, total sugars, lycopene, β-carotene and micronutrients Zn, Fe, N and P in cherry tomato fruits. Fertilization with CO1 and CO2 increased AT, Mn and decreased the SS / AT, K and Ca ratio. There was no nutritional deficiency of tomatoes in any of the proportions of the organic residues studied.

Leaf and Stem Anatomy of Cherry Tomato Under Calcium and Magnesium Deficiencies

Abstract Studies evaluating the influence of nutrients on plant anatomy are very important because nutritional deficiencies can alter the thickness and shape of certain tissues, compromising their functionality what can explain the reduction of productivity. The aim of this study was to characterize the anatomical changes in cherry tomato plants subjected to calcium (Ca) and magnesium (Mg) deficiencies. The experiment was conducted in nutrient solution and the plants subjected to three treatments: complete solution (Control), Ca restriction (1 mmol L-1 of Ca) and Mg omission (without Mg). The experimental design was completely randomized, with three repetitions. Sixty days after seedling transplanting leaves and stem were collected and submitted to anatomical evaluations. Ca or Mg deficiency promotes most evident anatomical changes in chlorophyllous and vascular tissues of the leaves, rather than in the stems. Leaves of 'Sindy' tomato plants with a concentration of 1.7 g kg-1 of Mg and visual symptoms of Mg deficiency present hyperplasia of both tissues, phloem and xylem. This deficiency also promotes increases in the thickness of mesophyll, spongy parenchyma and palisade parenchyma, and consequently of leaf thickness. The midrib of the leaves with a concentration of 10 g kg-1 of Ca, without visual symptoms of deficiency presented phloem hypertrophy and hyperplasia.

Effects of flooding stress in tomato plants transformed with different levels of mitochondrial sHSP23 6 / Efeitos do estresse por alagamento em plantas de tomateiro transformada com diferentes níveis de sHSP23 6 mitocondrial

Abstract Soil flooding is an environmental stressor for crops that can affect physiological performance and reduce crop yields. Abiotic stressors cause changes in protein synthesis, modifying the levels of a series of proteins, especially the heat shock proteins (HSP), and these proteins can help protect the plants against abiotic stress. The objective of this study was to verify if tomato plants cv. Micro-Tom from different genotypes with varying expression levels of MT-sHSP23.6 (mitochondrial small heat shock proteins) have different responses physiological to flooding. Plants from three genotypes (untransformed, MT-sHSP23.6 sense expression levels and MT-sHSP23.6 antisense expression levels) were cultivated under controlled conditions. After 50 days, the plants were flooded for 14 days. After this period half of the plants from each genotype were allowed to recover. Chlorophyll fluorescence, gas exchange, chlorophyll index, leaf area and dry matter were evaluated. Flood stress affected the photosynthetic electron transport chain, which is related to inactivation of the oxygen-evolving complex, loss of connectivity among units in photosystem II, oxidation-reduction of the plastoquinone pool and activity of photosystem I. The genotype with MT-sHSP23.6 sense expression levels was less sensitive to stress from flooding.

Resumo O alagamento do solo é um estressor ambiental para as culturas e pode afetar o desempenho fisiológico e reduzir a produtividade das culturas. Estresses abióticos causam mudanças na síntese de proteínas, modificando os níveis de uma série de proteínas, em especial as proteínas de choque térmico (HSP) e essas proteínas são conhecidas por proteger as plantas contra estresses abióticos. O objetivo deste estudo foi verificar se as plantas do tomateiro cv. Micro-Tom de distintos genótipos com diferentes níveis de expressão da MT-sHSP23.6 (proteínas mitocondriais de choque térmico com pequena massa molecular), têm diferentes respostas fisiológicas ao alagamento. As plantas de três genótipos (não-transformado, transformado com orientação antisense e transformado com orientação sense para MT-sHSP23.6) foram cultivadas sob condições controladas. Após 50 dias as plantas foram alagadas durante 14 dias. Após esse período as plantas de cada genótipo foram recuperadas. Foram avaliados fluorescência da clorofila, trocas gasosas, índice de clorofila, área foliar e massa seca. O estresse por alagamento afetou a cadeia de transporte de elétrons da fotossíntese, que está relacionado à inativação do complexo de evolução do oxigênio, perda da conectividade entre as unidades do fotossistema II, de oxidação e redução do pool de plastoquinona e atividade do fotossistema I. O genótipo com orientação sense MT-sHSP23.6 foi menos sensível ao estresse por alagamento.

Root phosphoenolpyruvate carboxylase and NAD-malic enzymes activity increase the ammonium-assimilating capacity in tomato.

Plant ammonium tolerance has been associated with the capacity to accumulate large amounts of ammonium in the root vacuoles, to maintain carbohydrate synthesis and especially with the capacity of maintaining high levels of inorganic nitrogen assimilation in the roots. The tricarboxylic acid cycle (TCA) is considered a cornerstone in nitrogen metabolism, since it provides carbon skeletons for nitrogen assimilation. The hypothesis of this work was that the induction of anaplerotic routes of phosphoenolpyruvate carboxylase (PEPC), malate dehydrogenase (MDH) and malic enzyme (NAD-ME) would enhance tolerance to ammonium nutrition. An experiment was established with tomato plants (Agora Hybrid F1) grown under different ammonium concentrations. Growth parameters, metabolite contents and enzymatic activities related to nitrogen and carbon metabolism were determined. Unlike other tomato cultivars, tomato Agora Hybrid F1 proved to be tolerant to ammonium nutrition. Ammonium was assimilated as a biochemical detoxification mechanism, thus leading to the accumulation of Gln and Asn as free amino acids in both leaves and roots as an innocuous and transitory store of nitrogen, in addition to protein synthesis. When the concentration of ammonium in the nutrient solution was high, the cyclic operation of the TCA cycle seemed to be interrupted and would operate in two interconnected branches to provide α-ketoglutarate for ammonium assimilation: one branch supported by malate accumulation and by the induction of anaplerotic PEPC and NAD-ME in roots and MDH in leaves, and the other branch supported by stored citrate in the precedent dark period.