Metabolic and molecular events occurring during chromoplast biogenesis

Chromoplasts are nonphotosynthetic plastids that accumulate carotenoids. They derive from other plastid forms, mostly chloroplasts. The biochemical events responsible for the interconversion of one plastid form into another are poorly documented. However, thanks to transcriptomics and proteomics approaches, novel information is now available. Data of proteomic and biochemical analysis revealed the importance of lipid metabolism and carotenoids biosynthetic activities. The loss of photosynthetic activity was associated with the absence of the chlorophyll biosynthesis branch and the presence of proteins involved in chlorophyll degradation. Surprisingly, the entire set of Calvin cycle and of the oxidative pentose phosphate pathwaypersisted after the transition from chloroplast to chromoplast. The role of plastoglobules in the formation and organisation of carotenoid-containing structures and that of the Or gene in the control of chromoplastogenesis are reviewed. Finally, using transcriptomic data, an overview is given the expression pattern of a number of genes encoding plastid-located proteins during tomato fruit ripening

Current challenges in postharvest biology of fruit ripening

This paper reviews the recent advances in the understanding of the fruit ripening process and describes future challenges. Fruit ripening is a complex developmental process which is orchestrated by the expression of ripening-related genes under the control of a network of signaling pathways. In climacteric fruit components responsible for the production of climacteric ethylene have been identified. Less progress has been made on non-climacteric fruit. Great advances have been made in the characterization of transcription factors (ERFs, RIN, etc...) that induce gene expression through the binding to their promoters. Genetic resources, genome sequencing and “omics” tools have been developed bringing a huge amount of data that will help to draw together an integrative network of regulatory and signaling pathways responsible for triggering and coordinating the ripening process. The discovery that some ripening events are controlled at the epigenetic level and, not in relation with the DNA sequences, opens novel perspectives

Physico-chemical composition of wine grapes berries in summer and winter growing seasons

Este trabalho teve como objetivo avaliar o potencial de maturação das cultivares Pinot Noir, Tempranillo, Merlot, Cabernet Sauvignon, Syrah, Chardonnay e Sauvignon Blanc submetidas ao regime de dupla poda, em Cordislândia, região cafeeira do sul de Minas Gerais. As plantas foram submetidas a dois ciclos de produção, um de primavera-verão, compreendido entre agosto e janeiro, e outro ciclo de outono-inverno, entre janeiro e julho. Como parâmetros de qualidade, foram avaliados os diâmetros transversal e longitudinal da baga, acidez, ácidos tartárico e málico, pH, sólidos solúveis, antocianinas, fenólicos totais e os teores de glicose, frutose e sacarose. Todas as variedades apresentaram maiores teores de pH, sólidos solúveis, açúcares, antocianinas e fenólicos totais, e redução nos diâmetros transversal e longitudinal na safra de inverno. A cultivar Syrah destacou-se das demais no conteúdo de antocianinas e fenólicos totais tanto no verão quanto no inverno, entretanto apresentou o menor conteúdo de açúcares. A alteração do ciclo de produção da videira através da técnica da dupla poda para colheita, no período de inverno, na região cafeeira de Minas Gerais, favorece a maturação dos frutos e melhora consideravelmente a qualidade das uvas para vinificação.This work aimed to evaluate some ripening parameters of cultivars Pinot Noir, Tempranillo, Merlot, Cabernet Sauvignon, Syrah, Chardonnay and Sauvignon Blanc submitted to the double-pruning management in Cordislândia, in the coffee region of the south of Minas Gerais State. Grapevines were cultivated in two different growing seasons, spring-summer from August to January and autumn-winter from January to July. Quality parameters such as berry transversal and longitudinal diameters, acidity, tartaric and malic acids, pH, soluble solids, anthocyanins, phenolic compounds, glucose, fructose and sucrose were evaluated. All cultivars showed higher pH, soluble solids, sugars, anthocyanins and phenolic compounds levels and lower transversal and longitudinal diameters in winter cycle. Syrah cultivar pointed out with higher anthocyanin and phenolic compounds levels in summer and winter cycles however showed lower reducing sugars levels in must. The alteration of the production cycle through double-pruning management in order to harvest grapes in the winter in the coffee region of Minas Gerais favours the ripening of the fruits and improves the quality of wine grapes.(FAPEMIG) Fundação de Amparo à Pesquisa do Estado de Minas GeraisConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Comprehensive Profiling of Ethylene Response Factor Expression Identifies Ripening-Associated ERF Genes and Their Link to Key Regulators of Fruit Ripening in Tomato

Our knowledge of the factors mediating ethylene-dependent ripening of climacteric fruit remains limited. The transcription of ethylene-regulated genes is mediated by ethylene response factors (ERFs), but mutants providing information on the specific role of the ERFs in fruit ripening are still lacking, likely due to functional redundancy among this large multigene family of transcription factors. We present here a comprehensive expression profiling of tomato (Solanum lycopersicum) ERFs in wild-type and tomato ripening-impaired tomato mutants (Never-ripe [Nr], ripening-inhibitor [rin], and non-ripening [nor]), indicating that out of the 77 ERFs present in the tomato genome, 27 show enhanced expression at the onset of ripening while 28 display a ripeningassociated decrease in expression, suggesting that different ERFs may have contrasting roles in fruit ripening. Among the 19 ERFs exhibiting the most consistent up-regulation during ripening, the expression of 11 ERFs is strongly down-regulated in rin, nor, and Nr tomato ripening mutants, while only three are consistently up-regulated. Members of subclass E, SlERF.E1, SlERF.E2, and SlERF.E4, show dramatic down-regulation in the ripening mutants, suggesting that their expression might be instrumental in fruit ripening. This study illustrates the high complexity of the regulatory network connecting RIN and ERFs and identifies subclass E members as the most active ERFs in ethylene- and RIN/NOR-dependent ripening

Altitude influence on the quality of 'Chardonnay' and 'Pinot Noir' grapes in the state of Minas Gerais

No Sul e Sudeste brasileiros, o excesso de chuvas durante o período de maturação afeta negativamente a qualidade dos vinhos tintos. Por outro lado, estas regiões possuem potencial para a elaboração de espumantes, uma vez que, para a elaboração desta bebida, a uva é colhida antes de completar o amadurecimento. No Estado de Minas Gerais, as condições de verão chuvoso estão presentes em todas as regiões de potencial vitícola, e a variação de altitude entre elas pode exercer influência na composição das uvas. Desta forma, este estudo buscou avaliar o potencial de maturação de uvas 'Chardonnay' e 'Pinot Noir' destinadas à elaboração de espumantes em dois locais de Minas Gerais: Cordislândia (873m) e Caldas (1.150m). As plantas foram enxertadas sobre 1.103 Paulsen e conduzidas em espaldeira. Foram avaliados os teores de sólidos solúveis totais, acidez total, ácidos málico e tartárico, e pH do mosto, tamanho e massa das bagas, compostos fenólicos nas cascas e sementes, antocianinas na casca e açúcares solúveis nas bagas, em duas safras consecutivas. As bagas apresentaram maior tamanho e massa quando cultivadas em Caldas. As uvas colhidas em Cordislândia apresentaram maior grau de maturação, sendo observados maior pH, maiores teores de glicose e frutose, e quantidade inferior de acidez e fenólicos totais nas sementes. Os maiores teores de ácido málico presentes nas uvas provenientes de Caldas sugerem que esta região pode ser mais indicada à produção de uvas para elaboração de vinhos espumantes.In the southern and southeastern of Brazil, the excessive rainfall during the maturation period negatively affects the quality of red wines. On the other hand, these regions have great potential for the development of sparklings since that for the elaboration of this drink, the grape is harvested before complete its maturation. In the state of Minas Gerais, the conditions of rainy summer season are present in all regions of grape production potential, and the altitude variation between them influence on the grapes composition. Therefore, this study sought to evaluate the potential for maturing of the grapes 'Chardonnay' and 'Pinot Noir' which are designated for the preparation of sparklings in two locations of Minas Gerais: Cordislândia (873m) and Caldas (1150m). The plants were grafted on 1103 Paulsen and conducted in trellis. It was evaluated the contents of total soluble solids, total acidity, malic and tartaric acid, and pH of the wort, size and mass of the berries, phenolic compounds in the peels and in the seeds, anthocyanins in the peels and soluble sugars in the berries in two seasons in a row. The berries had higher size and mass when grown in Caldas. The grapes harvested in Cordislândia presented a higher maturity degree, and it was observed a higher pH, higher levels of glucose and fructose, and a lower amount of acidity and total phenolic content in the seeds. The highest levels of malic acid present in the grapes of Caldas suggest that this region may be more appropriate for the production of grapes which are used for making sparklings.FAPEMIGCNP

The Starch Is (Not) Just Another Brick in the Wall: The Primary Metabolism of Sugars During Banana Ripening

The monocot banana fruit is one of the most important crops worldwide. As a typical climacteric fruit, the harvest of commercial bananas usually occurs when the fruit is physiologically mature but unripe. The universal treatment of green bananas with ethylene or ethylene-releasing compounds in order to accelerate and standardize the ripening of a bunch of bananas mimics natural maturation after increasing the exogenous production of ethylene. The trigger of autocatalytic ethylene production regulated by a dual positive feedback loop circuit derived from a NAC gene and three MADS genes results in metabolic processes that induce changes in the primary metabolism of bananas. These changes include pulp softening and sweetening which are sensorial attributes that determine banana postharvest quality. During fruit development, bananas accumulate large amounts of starch (between 15 and 35% w/w of their fresh weight, depending on the cultivar). Pulp softening and sweetening during banana ripening are attributed not only to changes in the activities of cell wall hydrolases but also to starch-to-sugar metabolism. Therefore, starch granule erosion and disassembling are key events that lead bananas to reach their optimal postharvest quality. The knowledge of the mechanisms that regulate sugar primary metabolism during banana ripening is fundamental to reduce postharvest losses and improve final product quality, though. Recent studies have shown that ethylene-mediated regulation of starch-degrading enzymes at transcriptional and translational levels is crucial for sugar metabolism in banana ripening. Furthermore, the crosstalk between ethylene and other hormones including indole-3-acetic acid and abscisic acid also influences primary sugar metabolism. In this review, we will describe the state-of-the-art sugar primary metabolism in bananas and discuss the recent findings that shed light on the understanding of the molecular mechanisms involved in the regulation of this metabolism during fruit ripening

Ethylene Modulates the Developmental Plasticity and the Growth Balance Between Shoot and Root Systems in the In Vitro Grown Epiphytic Orchid Catasetum fimbriatum

The epiphytic habitat is potentially one of the most stressful environments for plants, making the effective developmental control in response to external cues critical for epiphyte survival. Because ethylene mediates several abiotic stresses in plants, here, we have examined the ethylene influence in both shoot and root systems of the epiphytic orchid Catasetum fimbriatum. Under controlled conditions, ethylene production was quantified during an entire growth cycle of C. fimbriatum development in vitro, while treatments modulating either ethylene concentration or perception were carried out over the early growth phase of these plants. After treatments, growth measurements and histological features were studied in both shoot and root tissues. Ethylene production showed a decreasing trend over the period of organ elongation; however, it increased considerably when leaves were shed, and a new axillary bud was initiating. The early exposure of young plants to higher concentrations of ethylene triggered morphogenic responses that included root hair formation instead of velamen, and a combination of inhibitory effects (decreases in both stem enlargement and cellular/organ elongation) and inductive effects (increases in leaf and root formation, bud initiation and cellular thickening) on plant growth, which favored biomass allocation to roots. Conversely, inhibition of ethylene perception over the plant growth phase generally resulted in the opposite morphogenic responses. Our data indicate that periodic variations in ethylene concentration and/or sensitivity seem to modulate several developmental features in shoot and root systems of C. fimbriatum which could have adaptive significance during the growing phase of this epiphytic orchid.The authors thank Rohm and Haas Co. for a generous donation of the 1-methylcyclopropene (SmartFresh®), the inhibitor of ethylene perception used in several experiments presented in this article. This study was supported by the Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) through financial assistance to the Laboratory of Plant Physiology – IBUSP (Grant No. 04/08049–0 to GBK) and a PhD fellowship to MA Rodrigues (No. 04/08891–2)

Auxin production by the plant trypanosomatid Phytomonas\ud serpens and auxin homoeostasis in infected tomato fruits

Previously we have characterized the complete gene encoding a pyruvate decarboxylase (PDC)/indolepyruvate\ud decarboxylase (IPDC) of Phytomonas serpens, a trypanosomatid highly abundant in tomato fruits. Phylogenetic analyses\ud indicated that the clade that contains the trypanosomatid protein behaves as a sister group of IPDCs of γ-proteobacteria.\ud Since IPDCs are key enzymes in the biosynthesis of the plant hormone indole-3-acetic acid (IAA), the ability for IAA\ud production by P. serpens was investigated. Similar to many microorganisms, the production of IAA and related indolic\ud compounds, quantified by high performance liquid chromatography, increased inP. serpens media in response to amounts\ud of tryptophan. The auxin functionality was confirmed in the hypocotyl elongation assay. In tomato fruits inoculated with\ud P. serpensthe concentration of free IAA had no significant variation, whereas increased levels of IAA-amide and IAA-ester\ud conjugates were observed. The data suggest that the auxin produced by the flagellate is converted to IAA conjugates,\ud keeping unaltered the concentration of free IAA. Ethanol also accumulated inP. serpens-conditioned media, as the result of\ud a PDC activity. In the article we discuss the hypothesis of the bifunctionality of P. serpens PDC/IPDC and provide a\ud three-dimensional model of the enzyme.FAPESP) (grant number 2010/50957-1)(CNPq) (grant number 304793/2009-4)FAPESP (grant number 2008/50209-5

Fruit composition of 'Niágara Rosada' and 'Folha-de-Figo' grapevines under different training systems

RESUMO Este trabalho teve como objetivo avaliar a influência do sistema de condução na qualidade de bagas de uvas 'Niágara Rosada' e 'Folha-de-Figo' cultivadas em Caldas-MG. Foram avaliados a produção por planta, o diâmetro, a massa, o teor de potássio e a temperatura das bagas, pH, teor de sólidos solúveis, açúcares redutores, acidez total e ácidos orgânicos do mosto, compostos fenólicos nas cascas e sementes, e antocianinas. As plantas foram conduzidas em espaldeira, lira, latada ou cordão simples, e os frutos, avaliados nas safras de 2006 e 2007. As videiras de 'Niágara Rosada' cultivadas em latada e 'Folha-de-Figo' em lira apresentaram produção significativamente superior aos demais sistemas de condução. Em todos os casos, as bagas apresentaram temperatura inferior à ambiente, indicando sombreamento completo ou parcial dos cachos. No sistema latada, houve menor acúmulo de sólidos solúveis e açúcares redutores nas duas cultivares. Estes resultados preliminares indicam que a composição das bagas foi pouco influenciada pelo sistema de condução.ABSTRACT This work aimed on evaluating the influence of training systems in berries composition of 'Niágara Rosada' and 'Folha-de-Figo' grapevines grown in Caldas, MG. Yield per plant; diameter, weight, temperature and potassium content of the berries; pH, soluble solids, reducing sugars, total acidity and organic acids of the must; anthocyanins and phenolic compounds of the skins and phenolic compounds of the seeds were evaluated in grapevines training in vertical shoot position, lyre trellis, pergola Veronese or simple string in 2006 and 2007 seasons. 'Niágara Rosada' and 'Folha-de-Figo' grapevines training in pergola Veronese and lyre trellis, respectively, showed higher yield than the other training systems under study. Berries grown under the four different training systems were cooler than ambient temperature, resulting from partial or deep shade clusters. Berries harvested from pergola Veronese trellis system showed lower soluble solids and reducing sugars levels in both cultivars. These preliminary data show that training systems exerted little influence on berries composition.FAPEMIG e CNP