Growth temperature influences postharvest glucosinolate concentrations and hydrolysis product formation in first and second cuts of rocket salad

Rocket salad species (Diplotaxis tenuifolia and Eruca sativa; also known as E. vesicaria) are known for their high concentrations of health-related isothiocyanates, which are derived from secondary metabolites called glucosinolates. Increases in temperature due to climate change and extreme weather event frequencies over the coming decades are likely to influence not only the growth of leafy vegetables, but also their nutritional density. It is therefore essential to determine the impacts of these in order to mitigate crop losses and nutritional decline in future. Our data show there is a strong influence of pre-harvest growth temperatures on glucosinolate biosynthesis and formation of glucosinolate hydrolysis products postharvest, and that this is genotype dependent. High growth temperature (40 °C) severely retarded germination, growth, regrowth, and survival of rocket plants. Highest glucosinolate concentrations were observed in first and second cuts at 40 °C, but did not correspond to highest isothiocyanate concentrations (observed at 30 °C, second cut). Hydrolysis product formation is proportionately not as great as glucosinolate increases at 40 °C, possibly due to inhibition of enzyme function(s) at higher temperatures. These data indicate that high growth temperatures increase glucosinolate accumulation, but growth and productivity is significantly reduced. Much greater emphasis is needed for breeding cultivars tolerant to high growth temperatures in order to maximise nutritional benefits imparted by temperature stress

Analysis of growth physiology and phytochemical content of Eruca and Diplotaxis Cultivars under different light and temperature regimes

Rocket is a leafy brassicaceous salad crop that encompasses two major genera (Diplotaxis and Eruca) and many different cultivars. Rocket is a rich source of antioxidants and glucosinolates, many of which are produced as secondary products by the plant in response to stress. In this paper we examined the impact of temperature and light stress on several different cultivars of wild and salad rocket. Growth habit of the plants varied in response to stress and with different genotypes, reflecting the wide geographical distribution of the plant and the different environments to which the genera have naturally adapted. Preharvest environmental stress and genotype also had an impact on how well the cultivar was able to resist postharvest senescence, indicating that breeding or selection of senescence-resistant genotypes will be possible in the future. The abundance of key phytonutrients such as carotenoids and glucosinolates are also under genetic control. As genetic resources improve for rocket it will therefore be possible to develop a molecular breeding programme specifically targeted at improving stress resistance and nutritional levels of plant secondary products. Concomitantly, it has been shown in this paper that controlled levels of abiotic stress can potentially improve the levels of chlorophyll, carotenoids and antioxidant activity in this leafy vegetable

Effects of postharvest relative humidity and various re-cutting on vase life of cut rose flowers

Studies were conducted to evaluate the effects of different relative humidity levels (60%, 75%, and 90%) and re-cutting (0 cm, 1 cm, 2 cm, 3 cm, 4 cm, and 5 cm re-cutting end of flower stem) treatments on vase life of cut rose flower. Two separate experiments (bucket and vase experiments) were conducted based on completely randomised design with factorial arrangement with eight replications in bucket experiment and five replications in vase experiment. Analysis of variance revealed that two ways effect of various RH and re-cuts did not significantly (P ≤ 0.05) affected flower vase life, relative fresh weight, solution uptake, and bacterial populations. Cut rose flower stored in chamber with 90% relative humidity had the longest vase life, while those one kept in 60% showed the shortest longevity. The result of mean comparisons revealed with increasing relative humidity from 60% to 90%, bacterial populations was increased too

A universal primer for isolation of fragments of a gene encoding phytoene desaturase for use in virus-induced gene silencing (VIGS) studies

We have been using Virus-Induced Gene Silencing (VIGS) to test the function of genes that are candidates for involvement in floral senescence. Although VIGS is a powerful tool for assaying the effects of gene silencing in plants, relatively few taxa have been studied using this approach, and most that have are in the Solanaceae. We typically use silencing of phytoene desaturase (PDS) in preliminary tests of the feasibility of using VIGS. Silencing this gene, whose product is involved in carotene biosynthesis, results in a characteristic photobleaching phenotype in the leaves. We have found that efficient silencing requires the use of fragments that are more than 90% homologous to the target gene. To simplify testing the effectiveness of VIGS in a range of species, we designed a set of universal primers to a region of the PDS gene that is highly conserved among species, and that therefore allows an investigator to isolate a fragment of the homologous PDS gene from the species of interest. We report the sequences of these primers and the results of VIGS experiments in horticultural species from the Asteraceae, Leguminosae, Balsaminaceae and Solanaceae

Use of mutants to dissect the role of ethylene signalling in organ senescence and the regulation of yield in Arabidopsis thaliana

The role of ethylene in regulating organ senescence in Arabidopsis has been investigated by studying the development of mutants that have an attenu- ated capacity to perceive the gas. The onset of leaf senescence and floral organ abscission was delayed in the ethylene-insensitive mutant etr1. The photosynthetic life span of rosette leaves was similarly extended in the gain- of-function mutant ers2, and this mutant also exhibited a delay in the timing of pod dehiscence primarily as a con- sequence of an extension in the final stages of senescence. A detailed analysis of yield revealed that whilst thousand grain weight was increased, by as much as 20 %, in etr1, ein4, and the loss-of-function mutant etr2, only the latter showed a significant increase in total weight of seeds produced per plant. The other studied mutants exhibited a reduction in total seed yield of almost 40 %. These observations are discussed in the context of the possible role of ethylene in regulating organ senescence and their significance in the breeding of crop plants with enhanced phenotypic characteristics

CRP commissioned external evaluation of CGIAR Research Program on Grain Legumes

Executive Summary The CGIAR Research Program (CRP) on Grain Legumes (referred to as Grain Legumes) is one of 15 CRPs. The Grain Legumes is led by the International Centre for Agricultural Research in the Semi-Arid Tropics (ICRISAT), which combines and coordinates the Research-for-Development (R4D) activities of eleven principal partners: four CGIAR centres (ICRISAT-lead centre, CIAT, ICARDA and IITA), a CGIAR Challenge Program (Generation), four major national agricultural research systems (EIAR, Ethiopia; EMBRAPA-Brazil, GDAR-Turkey and ICAR-India) and two USAID-supported legume Cooperative Research Support Programs, all of whom are leaders in grain legume research and development. Established in mid-2012, the program aimed to achieve five Intermediate Development Objectives (IDOs - Food Security, Income, Nutrition & Health, Productivity and Environment). The program was structured around eight Product Lines (PL) (i.e. technological innovations) intersecting five Strategic Components (SC), but in 2015, it was restructured along a more R4D output model into eight Flagship Projects (FP): 1) Managing Productivity; 2) Trait determination; 3) Trait deployment; 4) Seed systems, post-harvest processing and nutrition; 5) Capacity-building and partnerships; 6) Knowledge, impacts, priorities and gender organisation; 7) Tools and platforms for genotyping and bioinformatics; and 8) Management. Five FPs focus on R4D; FPs 5 and 6 are considered cross-cutting; FP 8 has an overarching objective. Over the three year period since its inception in July 1012, Grain Legumes has had a total budget of $140 million. The CRP Commissioned External Evaluation (CCEE) aims to provide an independent assessment of the Grain Legumes, including retrospective analyses of performance against the aims and objectives set out in the initial CRP proposal; and a forward-looking element that will examine the likelihood of success of the second funding phase. As such, the evaluation may guide decision-making internally by the Grain Legumes and externally by donors; as well as feeding into decisions on the next phase of CRPs, to start in 2017. Six criteria are being considered within the evaluation, from the point of view of the activity per se and the extent to which the CRP assists in the implementation of the activity: Relevance; Efficiency; Quality of science; Effectiveness; Impact; and Sustainability. Three cross-cutting issues: Gender, Capacity-building, and Partnerships, will be explored to gauge added value of the programme-integrating activities among participants and impact outcomes for its intended beneficiaries. The scope encompasses all activities, structures and institutions within the Grain Legumes. This evaluation of Grain Legumes has been commissioned by CRP management, managed by a CRP staff member specifically provided with the authority to manage evaluations, and overseen by an oversight body, which is set up specifically for the evaluation and includes independent members. To ensure the confidentiality of participants in the evaluation, information, e.g. from interviews and surveys, is kept in a secure location. The evaluation will use a variety of methods to address the evaluation criteria, including semi-structured interviews of Grain Legumes researchers and stakeholders; country field visits; review of a sample of Grain Legumes projects; focus group discussions; self-evaluation exercises; short E-surveys; and an examination of documentation. The evaluation team consists of four independent evaluators looking specifically at the scope and focus of the CRP. The initial evaluation and the inception report were prepared over a short time period; given the size, complexity and numbers of crops in the CRP, this mitigates against a clear cut outcome from the evaluation. A further shortcoming is the lack of “management and evaluation” data. The team has also had no access to an IEA Evaluation Analyst. These limitations reduce the team’s ability to collect and analyse information. Additionally, the Management Entity has still not provided the Evaluation Team with consolidated details of contacts within the CRP, of external partners, of meetings and other events suitable for capturing multiple actors/stakeholders for interview. Key dates and activities in the evaluation include: late-April 2015 and ongoing: Desk-top review of research projects and SKYPE interviews with Product Line Coordinators and other key actors; May 2015: Country visit to INRA (Morocco) and IITA/INRAB (Benin); June 2015: Attend meeting in Montpelier and country visit to ICRISAT (India – Hyderabad and New Delhi); end June/July 2015: Country visit to Ethiopia, Kenya, Rwanda and Malawi; June2015: Grain Legumes scientist E-survey; July 2015: Data analysis and additional data collection as required; Draft report and recommendations circulated for comments; August 2015: Presentation of findings - to CGIAR in Hyderabad; Final report. This inception report sets out the proposals of the independent evaluation team regarding the purpose, objectives and scope of the evaluation, its target audiences and use; the evaluation objectives and approach; and the timeline and work-plan. This final draft incorporates stakeholder comments on the first draft

Perception of bitterness, sweetness and liking of different genotypes of lettuce

Lettuce is an important leafy vegetable, consumed across the world, containing bitter sesquiterpenoid lactone (SL) compounds that may negatively affect consumer acceptance and consumption. We assessed liking of samples with differing absolute abundance and different ratios of bitter:sweet compounds by analysing recombinant inbred lines (RILs) from an interspecific lettuce mapping population derived from a cross between a wild (L. serriola acc. UC96US23) and domesticated lettuce, (L. sativa, cv. Salinas). We found that the ratio of bitter:sweet compounds was a key determinant of bitterness perception and liking. We were able to demonstrate that SLs such as 8-deoxylactucin-15-sulphate contribute most strongly to bitterness perception, whilst 15-p-hydroxylphenylacetyllactucin-8-sulphate does not contribute to bitter taste. Glucose was the sugar most highly correlated with sweetness perception. There is a genetic basis to the biochemical composition of lettuce. This information will be useful in lettuce breeding programmes in order to produce leaves with more favourable taste profiles

Analysis of seven salad rocket (Eruca sativa) accessions: the relationships between sensory attributes and volatile and non-volatile compounds

Sensory and chemical analyses were performed on accessions of rocket (Eruca sativa) to determine phytochemical influences on sensory attributes. A trained panel was used to evaluate leaves, and chemical data were obtained for polyatomic ions, amino acids, sugars and organic acids. These chemical data (and data of glucosinolates, flavonols and headspace volatiles previously reported) were used in Principal Component Analysis (PCA) to determine variables statistically important to sensory traits. Significant differences were observed between samples for polyatomic ion and amino acid concentra- tions. PCA revealed strong, positive correlations between glucosinolates, isothiocyanates and sulfur com- pounds with bitterness, mustard, peppery, warming and initial heat mouthfeel traits. The ratio between glucosinolates and sugars inferred reduced perception of bitter aftereffects. We highlight the diversity of E. sativa accessions from a sensory and phytochemical standpoint, and the potential for breeders to create varieties that are nutritionally and sensorially superior to existing ones

Phenolics pattern of cut H3O rose flowers during floral development

An experiment was conducted to evaluate the phenolic acids and flavonoids contents from flower bud to flower senescence stages (7 stages) in cut H3O roses every other day. Some phenolic acids (Gallic, Caffeic, Caftaric, Chlorogenic, Chiconic, Coumaric, Sinapic, and Ferulic) and flavonoids (Catechin, Pelargonidin chloride, Cyanidin, Kaempferol, and Quercetin) were detected in the methanolic extract of rose petals by HPLC. Data analysis revealed that Gallic acid content did not significantly (P ≤ 0.05) affects from the flower bud to the senescence stages. However, it’s found that Caftaric acid, Chlorogenic acid, Coumaric acid, Ferulic acid, Chiconic acid, Quercetin, and Kaempferol (at P ≤ 0.05), Catechin, Caffeic acid, Sinapic acid, Cyanidin, and Pelargonidin chloride contents (at P ≤ 0.01) significantly affected during flower opening stages. The highest contents of phenolics during development of cut H3O rose flowers were as follow: day 1 [Coumaric acid], day 3 [Caftaric acid, Ferulic acid, and Kaempferol], day 5 [no compound was found], day 7 [Sinapic acid and Cyanidin], day 9 [Chlorogenic acid], day 11 [Chiconic acid and Quercetin], and day 13 [Caffeic acid, Catechin, and Pelargonidin chloride]. The results showed that flower development stages can be suggested to consider the phenolic compounds required to use in the therapeutic process

High glucosinolate content in rocket leaves (Diplotaxis tenuifolia and Eruca sativa) after multiple harvests is associated with increased bitterness, pungency, and reduced consumer liking

Rocket (Diplotaxis tenuifolia and Eruca sativa) leaves delivered to the UK market are variable in appearance, taste, and flavour over the growing season. This study presents sensory and consumer analyses of rocket produce delivered to the UK over the course of one year, and evaluated the contribution of environmental and cultivation factors upon quality traits and phytochemicals called glucosinolates (GSLs). GSL abundance was positively correlated with higher average growth temperatures during the crop cycle, as well as perceptions of pepperiness, bitterness, and hotness. This in turn was associated with reduced liking, and corresponded to low consumer acceptance. Conversely, leaves with greater sugar content were perceived as more sweet, and had a higher correlation with consumer acceptance of the test panel. First cut leaves of rocket were favored more by consumers, with multiple leaf cuts associated with low acceptance and higher glucosinolate concentrations. Our data suggest that the practice of harvesting rocket crops multiple times reduces consumer acceptability due to increases in GSLs, and the associated bitter, hot and peppery perceptions some of their hydrolysis products produce. This may have significant implications for cultivation practices during seasonal transitions, where leaves typically receive multiple harvests and longer growth cycles