High species richness of native pollinators in Brazilian tomato crops / Alta riqueza de espécies de polinizadores nativos em plantações Brasileiras de tomateiro

Abstract Pollinators provide an essential service to natural ecosystems and agriculture. In tomatoes flowers, anthers are poricidal, pollen may drop from their pore when flowers are shaken by the wind. However, bees that vibrate these anthers increase pollen load on the stigma and in fruit production. The present study aimed to identify the pollinator richness of tomato flowers and investigate their morphological and functional traits related to the plant-pollinator interaction in plantations of Central Brazil. The time of anthesis, flower duration, and the number and viability of pollen grains and ovules were recorded. Floral visitors were observed and collected. Flower buds opened around 6h30 and closed around 18h00. They reopened on the following day at the same time in the morning, lasting on average 48 hours. The highest pollen availability occurred during the first hours of anthesis. Afterwards, the number of pollen grains declined, especially between 10h00 to 12h00, which is consistent with the pollinator visitation pattern. Forty bee species were found in the tomato fields, 30 of which were considered pollinators. We found that during the flowering period, plants offered an enormous amount of pollen to their visitors. These may explain the high richness and amount of bees that visit the tomato flowers in the study areas. The period of pollen availability and depletion throughout the day overlapped with the bees foraging period, suggesting that bees are highly effective in removing pollen grains from anthers. Many of these grains probably land on the stigma of the same flower, leading to self-pollination and subsequent fruit development. Native bees (Exomalopsis spp.) are effective pollinators of tomato flowers and are likely to contribute to increasing crop productivity. On the other hand, here tomato flowers offer large amounts of pollen resource to a high richness and amount of bees, showing a strong plant-pollinator interaction in the study agroecosystem.

Resumo Polinizadores fornecer um serviço essencial para os ecossistemas naturais e para agricultura. Em tomateiros, as anteras são poricidas e o pólen pode sair a partir dos poros quando as flores são agitadas pelo vento. No entanto, as abelhas que vibram as anteras aumentam a carga de pólen no estigma e na produção de frutos. O presente estudo teve como objetivo identificar a riqueza dos polinizadores das flores de tomate e investigar suas características morfológicas e funcionais relacionadas com a interação planta-polinizador em plantações do Brasil central. Foram registrados o tempo de antese, duração flor, bem como o número e viabilidade de grãos de pólen e óvulos. Os visitantes florais foram observados e coletados. Os botões florais abriram-se em torno 06h30 e fechou em torno de 18h00. As flores reabrem no dia seguinte ao mesmo tempo na parte da manhã, com longevidade média de 48 horas. A maior disponibilidade de pólen ocorreu durante as primeiras horas da antese. Depois disso, o número de grãos de pólen diminuiu, especialmente entre as 10h00 às 12h00, o que é consistente com os padrões de visitação de polinizadores. Quarenta espécies de abelhas foram encontradas nos campos de tomate, 30 das quais foram consideradas polinizadores. Durante o período de floração, as plantas oferecem enorme quantidade de pólen para os seus visitantes. Isto pode explicar a alta riqueza e quantidade de abelhas que visitam as flores de tomate nas áreas de estudo. O período de disponibilidade e redução de pólen durante todo o período do dia é sobreposto com o período de alimentação das abelhas, o que sugere que elas são altamente eficazes na remoção de grãos de pólen das anteras. Muitos desses grãos provavelmente são depositados no estigma da mesma flor, levando à auto-polinização e o desenvolvimento de frutos. Abelhas nativas (Exomalopsis spp.) são polinizadores efetivos de flores de tomate, podendo contribuir para o aumento da produtividade das culturas. Por outro lado, as flores de tomate oferecem grandes quantidades de pólen de recursos para uma alta riqueza e quantidade de abelhas, que mostram um estudo forte interação planta-polinizador nos agroecossistemas.

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.

Evaluation of extracts from potato and tomato wastes as natural antioxidant additives

The industrialization of potato and tomato produces large amount of wastes. Previous studies have demonstrated that these by-products are rich in antioxidant compounds. In this study, the composition and antioxidant efficacy of extracts from potato and tomato by-products were determined in order to evaluate their potential as food additives. Potato and tomato wastes showed to be good sources of fiber, protein and antioxidants. The antioxidant activity and total phenolic, carotenoid and lycopene contents were determined in methanol, ethanol and acetone extracts of the residues. Methanol was the best solvent for the extraction of phenolics while acetone was the best in the extraction of carotenoids in both residues. The greatest antioxidant activity (14.10 µmol Trolox/g) resulted when potato peels were extracted with ethanol. The oxidative stability of canola oil containing either ethanol extracts of potato and tomato wastes (200 and 400 mg/kg) or the synthetic antioxidant BHT (200 mg/kg), compared to oil without antioxidants, was evaluated by measuring their peroxide values, conjugated dienes and p-anisidine value after 72 and 144 h storage at 65 °C. The order of antioxidant efficacy was as follows: potato peels > BHT > tomato residues. The results showed that ethanol extracts of potato and tomato waste could be used as natural antioxidant additives in the protection of vegetable oils(AU)

La industrialización de la papa y el jitomate genera grandes cantidades de desechos. Estudios previos han demostrado que estos subproductos son ricos en compuestos antioxidantes. En este trabajo se determinaron la composición y la eficacia antioxidante de subproductos de papa y jitomate con el fin de evaluar su potencial como aditivos alimentarios. Los desechos de papa y jitomate demostraron ser buenas fuentes de fibra, proteína y antioxidantes. Se determinó la actividad antioxidante y el contenido de compuestos fenólicos, carotenoides y licopeno en extractos metanólicos, etanólicos y acetónicos de los residuos. El mejor disolvente para la extracción de compuestos fenólicos fue el metanol mientras que la acetona fue el mejor disolvente para extraer los carotenoides. La mayor actividad antioxidante (14.10 µmol Trolox/g) se obtuvo cuando las cáscaras de papa se extrajeron con etanol. La estabilidad oxidativa de aceite de canola adicionado con los extractos etanólicos de desechos de papa o jitomate (200 y 400 mg/kg) o con el antioxidante sintético BHT (200 mg/kg), comparándolos con aceite sin antioxidantes, se evaluó mediante la medición de su índice de peróxidos, dienos conjugados e índice de anisidina, después de almacenarlo a 65°C durante 72 y 144 h. El orden de eficacia antioxidante fue como sigue: cáscara de papa > BHT > residuos de jitomate. Los resultados demostraron que los extractos etanólicos de los desperdicios de papa y jitomate podrían ser usados como aditivos antioxidantes naturales en la protección de aceites vegetales(AU)

Plant growth promoting capability and genetic diversity of bacteria isolated from mud volcano and lime cave of Andaman and Nicobar Islands

Twenty four bacterial strains from four different regions of mud volcano and lime cave were isolated to estimate their diversity, plant growth promoting and biocontrol activities to use them as inoculant strains in the fields. An excellent antagonistic effect against four plant pathogens and plant growth promoting properties such as IAA production, HCN production, phosphate solubilization, siderophore production, starch hydrolysis and hydrolytic enzymes syntheses were identified in OM5 (Pantoea agglomerans) and EM9 (Exiguobacterium sp.) of 24 studied isolates. Seeds (Chili and tomato) inoculation with plant growth promoting strains resulted in increased percentage of seedling emergence, root length and plant weight. Results indicated that co-inoculation gave a more pronounced effects on seedling emergence, secondary root numbers, primary root length and stem length, while inoculation by alone isolate showed a lower effect. Our results suggest that the mixed inocula of OM5 and EM9 strains as biofertilizers could significantly increase the production of food crops in Andaman archipelago by means of sustainable and organic agricultural system.

Microorganisms associated to tomato seedlings growing in saline culture act as osmoprotectant

Less than 0.5% of total water in the world is available for human consumption and agriculture. The major part of the world's water is saline and salinity in soils interferes in germination of seeds and the posterior development of the plant. In order to increase the osmotolerance of tomato, seedlings were associated with Azospirillum brasilense Cd, Azospirillum brasilense Cd transformed bacteria with a plasmid harboring a trehalose biosynthesis gene-fusion or Chlorella vulgaris. Two plant culture media: Hydroponic and Murashige and Skoog were tested. In the first set of studies seedlings were associated to single free cells meanwhile in a second set single and combined free cells were studied. A positive interaction between transformed Azospirillum and Chlorella vulagris and tomato plants was observed. Seedlings showed a salt concentration tolerance, as sodium chloride, up to 200 mM. According to our results, the association of plants with A. brasilense Cd-BIF and C. vulgaris is a viable approach to increase their salt tolerance and biomass, as consequence the possible use of sea water to irrigate horticultural plants.

Molecular battles between plant and pathogenic bacteria in the phyllosphere

The phyllosphere, i.e., the aerial parts of the plant, provides one of the most important niches for microbial colonization. This niche supports the survival and, often, proliferation of microbes such as fungi and bacteria with diverse lifestyles including epiphytes, saprophytes, and pathogens. Although most microbes may complete the life cycle on the leaf surface, pathogens must enter the leaf and multiply aggressively in the leaf interior. Natural surface openings, such as stomata, are important entry sites for bacteria. Stomata are known for their vital role in water transpiration and gas exchange between the plant and the environment that is essential for plant growth. Recent studies have shown that stomata can also play an active role in limiting bacterial invasion of both human and plant pathogenic bacteria as part of the plant innate immune system. As counter-defense, plant pathogens such as Pseudomonas syringae pv tomato (Pst) DC3000 use the virulence factor coronatine to suppress stomate-based defense. A novel and crucial early battleground in host-pathogen interaction in the phyllosphere has been discovered with broad implications in the study of bacterial pathogenesis, host immunity, and molecular ecology of bacterial diseases.

Diallel analysis of production traits among domestic, exotic and mutant germplasms of Lycopersicon

The effects of wild germplasm on tomato fruit shelf life have not yet been completely evaluated. Three different genotypes of Lycopersicon esculentum (a cultivated variety, a homozygote for nor and a homozygote for rin), LA1385 of L. esculentum var. cerasiforme, LA722 of L. pimpinellifolium, and 10 diallel hybrids were assayed. Mean values of fruit shelf life, weight, shape, and mean number of flowers per cluster were analyzed after Griffing (1956, Aust. J. Biology 9: 463-493), method 2, model 1. Both general and specific combining abilities (GCA and SCA) were significant for the four traits. Negative unidirectional dominance was detected for fruit weight and shelf life, while bidirectional dominance was detected for fruit shape and mean number of flowers per cluster. SCA was greater than GCA for shelf life, so nonadditive effects predominantly accounted for this trait. In the heterozygous state, rin had smaller mean effects than nor. Wild accessions were able to prolong shelf life per se, and in crosses to the cultivated variety. The cross between the homozygote for nor and LA722 yielded the longest shelf life among hybrids

Effect of mode of application of some growth regulators on the physiology of tomato plants: I effect of IAA on the endogenous hormonal contents

Application of 10 ppm IAA concentrations to the culture media or used as foliar spray of tomato plants caused stimulatory effects on growth, differentiation, development and fruiting of plants. 40 ppm concentration however, caused less activation than that exerted by 10 ppm concentration. This was accompanied with regular increases in the contents and levels of auxins, gibberellins and cytokinins leading to hormonal balance. The high concentration of IAA [80 ppm] however induced inhibiting effect on the previously mentioned phenomena which were accompanied with increases in the level and activity of endogenous inhibitors mainly unsaturated lactones and also with low levels of auxins, gibberellins and cytokinins leading to hormonal imbalance. Also the IAA oxidase activity was enhanced by the application of higher concentration of IAA. These results can easily interpret the previously mentioned results in the first paper of this series

Hormonal changes of tomato seedlings produced from seeds germinating in different concentrations of IAA or nicotinamide

IAA at 10 ppm concentration promoted the percent germination of tomato seeds more than 40 ppm concentration but 80 ppm concentration was inhibitory. With nicotinamide the percent germination increased by the increase of concentration. The hypocotyl and radical lengths of the seedlings arising from seeds treated differently go generally parallel to the corresponding germination rates with characteristic increase in branching of radicals of seedlings arising from treated with 10 ppm IAA. The stimulatory effects of 10 ppm IAA concentration or 10, 40 and 80 ppm concentration of nicotinamide on germination or lengths of radicals and hypocotyls of the produced seedlings were accompanied with regular increases in the contents and levels of auxins, gibberellins and cytokinins, leading to hormonal balance, but 80 ppm IAA concentration caused reversed effects and increased the activity of IAA oxidase enzyme leading to hormonal imbalance

Some morphologic and physiologic responses of tomato plants to hydrogen sulphide

Fifty and Hundred ppm of H2 were supplied to tomato plants growing under field conditions. The results indicated that all growth parameters studied decreased. The reduction became greater when concentration and/or number of treatments increased. H2S induced significant inhibitory effects on photosynthetic activities, accumulation of soluble sugars, biosynthesis of polysaccharides and most of the soluble nitrogen. H2S greatly reduced the activities of peroxidase nitrate reductase and glutamate dehydrogenase enzymes. H2S also showed effects on different amino acid levels