Cultivar influence on carotenoid composition of loquats from Brazil.

Cultivar, growing conditions and geographical origin are factors that influence the carotenoid composition in fruits. Because the loquat cultivars evaluated in this study, Centena´ ria, Mizauto, Mizuho, Mizumo and Ne´ ctar de Cristal, have not previously been investigated, the present work was carried out to determine and compare the carotenoid composition of these five loquat cultivars, by applying high-performance liquid chromatography connected to a photodiode array and mass spectrometry detectors (HPLC-PDA-MS/MS). Twenty-five carotenoids were separated on a C 30 column, and 23 of them were identified. All-trans-b-carotene (19–55%), all-trans-b-cryptoxanthin (18–28%), 5,6:50,60-diepoxy-b-cryptoxanthin (9–18%) and 5,6-epoxy-b-cryptoxanthin (7–10%) were the main carotenoids. The total carotenoid content ranged from 196 mg/100 g (cv. Ne´ ctar de Cristal) to 3020 mg/ 100 g (cv. Mizumo). The carotenoid profile of cv. Ne´ ctar de Cristal was different from the other cultivars, which was in agreement with its cream pulp colour, in contrast to the other four cultivars with orange pulp colour. Cultivars Mizauto, Mizuho, Mizumo and Centena´ ria showed provitamin A values between 89 and 162 mg RAE/100 g, and can be considered good source of this provitamin

Carotenoid accumulation during tomato fruit ripening is modulated by the auxin-ethylene balance

Background : Tomato fruit ripening is controlled by ethylene and is characterized by a shift in color from green to red, a strong accumulation of lycopene, and a decrease in β-xanthophylls and chlorophylls. The role of other hormones, such as auxin, has been less studied. Auxin is retarding the fruit ripening. In tomato, there is no study of the carotenoid content and related transcript after treatment with auxin. Results : We followed the effects of application of various hormone-like substances to “Mature-Green” fruits. Application of an ethylene precursor (ACC) or of an auxin antagonist (PCIB) to tomato fruits accelerated the color shift, the accumulation of lycopene, α-, β-, and δ-carotenes and the disappearance of β-xanthophylls and chlorophyll b. By contrast, application of auxin (IAA) delayed the color shift, the lycopene accumulation and the decrease of chlorophyll a. Combined application of IAA + ACC led to an intermediate phenotype. The levels of transcripts coding for carotenoid biosynthesis enzymes, for the ripening regulator Rin, for chlorophyllase, and the levels of ethylene and abscisic acid (ABA) were monitored in the treated fruits. Correlation network analyses suggest that ABA, may also be a key regulator of several responses to auxin and ethylene treatments. Conclusions : The results suggest that IAA retards tomato ripening by affecting a set of (i) key regulators, such as Rin, ethylene and ABA, and (ii) key effectors, such as genes for lycopene and β-xanthophyll biosynthesis and for chlorophyll degradation

Volatile and Non-Volatile Compounds Profiling of Brazilian Pitanga (Eugenia uniflora L.) Varieties During Ripening using Gas Chromatography-Mass Spectrometry Approach.

Brazil is home to a rich biodiversity of native edible fruits renowned for their health-promoting compounds and flavors. Among these, Eugenia uniflora L. (Brazilian pitanga) is particularly notable. The fruit varies in color from yellow to purple and is prized for its intense aroma and versatile taste profile. However, information about the compounds responsible for their nutritional and sensory potential is still limited. This study analyzed volatile compounds and metabolites in yellow, red and purple pitanga fruits (Eugenia uniflora) at various ripening stages, exploiting a metabolomics approach. Yellow pitanga had 30 volatile compounds, with esters (40%), terpenes (26.67%) and aldehydes (16.67%) constituting 83.34% of identified volatile compounds. Red pitanga featured 26 volatile compounds, primarily terpenes and esters (each 30.77%) and aldehydes (15.38%), making up 76.92%. Purple pitanga contained 39 volatile compounds, with terpenes and esters (each 35.90%) and aldehydes (17.95%), totaling 89.75% of identified volatile compounds. Across all pitanga types, 124 metabolites were identified, including saturated fatty acids (17.74%), terpenes (17.74%) and sugars (16.93%), constituting 52.41% of identified metabolites. Future studies should provide nutritional information, consumption methods and industrial applications for pitanga fruits, focusing on sensory analysis, health benefits, preservation and breeding to enhance bioactive compounds and flavor

Evaluation of aluminium tolerance in grapevine rootstocks

Aluminum (Al) toxicity is a major worldwide agricultural problem. At low pH, Al speciates into the soluble and phyto-toxic form Al3+, inhibiting the root growth and affecting plant development. In Brazil, agriculture in acidic soils with elevated concentration of Al has significantly increased in the last decades. Therefore, in order to achieve efficient agriculture practices, the selection of plant cultivars with improved Al resistance has become crucial in this type of soils. In this work we have evaluated the Al resistance of six genotypes of grapevine rootstocks. The grapevine hardwood cuttings were grown in nutrient solution in the absence and presence of 250 and 500 μM Al at pH 4.2. The phenotypic indexes of relative root growth, fresh and dry root weight, root area, hematoxylin staining profile, and Al content were evaluated for all six genotypes. These phenotypic indexes allowed us to identify the 'Kober 5BB', 'Gravesac', 'Paulsen 1103', and 'IAC 766' grapevine rootstocks genotypes as the ones with the highest resistance to Al. Likewise, 'IAC 572' and 'R110 genotypes were the most Al-sensitive cultivars. We evaluated the root organic acid exudation profile in the most Al-resistant ('Kober 5BB') and most Al-sensitive ('R110') in plantlets cultivated in vitro in the absence and presence of 100, 200, and 400 μM of Al. Among several compounds detected, citrate was the only organic acid related to the Al resistance phenotype observed in the 'Kober 5BB' genotype. The high constitutive citrate exudation observed in 'Kober 5BB' strongly suggests that exudation of this particular organic acid may impart Al-resistance/amelioration in grapevine.

Multifaceted roles of nitric oxide in tomato fruit ripening: NO-induced metabolic rewiring and consequences for fruit quality traits

Nitric oxide (NO) has been implicated as part of the ripening regulatory network in fleshy fruits. However, very little is known about the simultaneous action of NO on the network of regulatory events and metabolic reactions behind ripening-related changes in fruit color, taste, aroma and nutritional value. Here, we performed an in-depth characterization of the concomitant changes in tomato (Solanum lycopersicum) fruit transcriptome and metabolome associated with the delayed-ripening phenotype caused by NO supplementation at the pre-climacteric stage. Approximately one-third of the fruit transcriptome was altered in response to NO, including a multilevel down-regulation of ripening regulatory genes, which in turn restricted the production and tissue sensitivity to ethylene. NO also repressed hydrogen peroxide-scavenging enzymes, intensifying nitro-oxidative stress and S-nitrosation and nitration events throughout ripening. Carotenoid, tocopherol, flavonoid and ascorbate biosynthesis were differentially affected by NO, resulting in overaccumulation of ascorbate (25%) and flavonoids (60%), and impaired lycopene production. In contrast, the biosynthesis of compounds related to tomato taste (sugars, organic acids, amino acids) and aroma (volatiles) was slightly affected by NO. Our findings indicate that NO triggers extensive transcriptional and metabolic rewiring at the early ripening stage, modifying tomato antioxidant composition with minimal impact on fruit taste and aroma.This work was supported by the São Paulo Research Foundation (FAPESP) (grants 2018/16389-8, 2016/04924-0, 2017/17935-3 and 2016/01128-9), Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) (grants 422287/2018-0, 305012/2018-5, 303332/2019-0 and 300986/2018-1), and Coordenação de Aperfeiçoamento de Pessoal de Nível Superior – Brasil (CAPES) – Finance Code 001. The research work of FJC and JMP is supported by a European Regional Development Fund cofinanced grant from the Ministry of Economy and Competitiveness (AGL2015-65104-P and PID2019-103924GB-I00), Spain

Ácido abscísico e óxido nítrico interagem na regulação da expressão do metabolismo ácido crassuláceo em abacaxizeiro.

O óxido nítrico (NO) pode atuar de forma regulatória numa vasta gama de processos metabólicos nas plantas, incluindo as respostas aos estresses bióticos e abióticos. Com relação aos estresses abióticos, pesquisas recentes têm demonstrado uma forte interação entre NO e ácido abscísico (ABA) na sinalização de processos desencadeados pelo estresse hídrico. Entretanto, a sinalização de algumas respostas decorrentes do estresse hídrico ainda não foram caracterizadas quanto à participação do NO, como é o caso da regulação da expressão do metabolismo ácido crassuláceo (CAM). Tendo em vista que o abacaxizeiro (Ananas comosus) comporta-se como uma espécie C3 - CAM facultativa quando cultivado in vitro, neste trabalho buscou-se analisar uma possível interação do ABA com o NO na regulação da expressão do CAM nessa bromélia

Proton and anion transport across the tonoplast vesicles in bromeliad species

Crassulacean acid metabolism (CAM) is one of the key innovations in the Neotropical family Bromeliaceae that has enabled many of its species to occupy seasonally water-limited terrestrial environments or microclimatically arid epiphytic niches. However, the relationship between CAM activity and the transport processes responsible for vacuolar organic-acid accumulation at night has not been systematically explored in this family. In the present investigation, ATP- and PPi-dependent proton transport rates were studied in tonoplast membrane vesicles isolated from leaves of six CAM and one C3 species of bromeliads. A consistent feature of these species was the high activity of the tonoplast ATP-driven H+ pump, which, when averaged across the seven species tested, showed a higher specific activity than the tonoplast PPi-driven H+ pump. For all CAM species, the rate of ATP-dependent proton transport into the tonoplast vesicles was strongly influenced by the nature of the balancing organic-acid anion, which displayed the following order of effectiveness: fumarate > malate > citrate. Measurements of leaf organic-acid content in six CAM bromeliads at dusk and dawn showed that nocturnal accumulation of malate exceeded citrate by a factor of ~2.4–20.0-fold in five of six bromeliad species used in this study, demonstrating a close correlation between the CAM rhythm and the intrinsic properties of the vacuolar membrane across which these organic acids are transported