Justyna Milc

Iodine Fortification Plant Screening Process and Accumulation in Tomato Fruits and Potato Tubers

Iodine is an essential microelement for human health, and the recommended daily allowance (RDA) of such element should range from 40 to 200 μg day−1. Because of the low iodine contents in vegetables, cereals, and many other foods, iodine deficiency disorder (IDD) is one of the most widespread nutrient-deficiency diseases in the world. Therefore, investigations of I uptake in plants with the aim of fortifying them can help reach the important health and social objective of IDD elimination. This study was conducted to determine the effects of the absorption of iodine from two different chemical forms—potassium iodide (I−) and potassium iodate (IO− 3)—in a wide range of wild and cultivated plant species. Pot plants were irrigated with different concentrations of I− or IO− 3, namely 0.05% and 0.1% (w/v) I− and 0.05%, 0.1%, 0.2%, and 0.5% (w/v) IO− 3. Inhibiting effects on plant growth were observed after adding these amounts of iodine to the irrigation water. Plants were able to tolerate high levels of iodine as IO− 3 better than I− in the root environment. Among cultivated species, barley (Hordeum vulgare L.) showed the lowest biomass reductions due to iodine toxicity and maize (Zea mays L.) together with tobacco (Nicotiana tabacum L.) showed the greatest. After the screening, cultivated tomato and potato were shown to be good targets for a fortification-rate study among the species screened. When fed with 0.05% iodine salts, potato (Solanum tuberosum L.) tubers and tomato (Solanum lycopersicum L.) fruits absorbed iodine up to 272 and 527 μg/100 g fresh weight (FW) from IO− 3 and 1,875 and 3,900 μg/100 g FW from I−. These uptake levels were well more than the RDA of 150 μg day−1 for adults. Moreover, the agronomic efficiency of iodine accumulation of potato tubers and tomato fruits was calculated. Both plant organs showed greater accumulation efficiency for given units of iodine from iodide than from iodate. This accumulation efficiency decreased in both potato tubers and tomato fruits at iodine concentrations greater than 0.05% for iodide and at respectively 0.2% and 0.1% for iodate. On the basis of the uptake curve, it was finally possible to calculate the doses of supply in the irrigation water of iodine as iodate (0.028% for potato and 0.014% for tomato) as well as of iodide (0.004% for potato and 0.002% for tomato) to reach the 150 μg day−1 RDA for adults in 100 g of such vegetables, to efficiently control IDD, although these results still need to be validated.

A genotypic and phenotypic information source for marker-assisted selection of cereals: the CEREALAB database

The CEREALAB database aims to store genotypic and phenotypic data obtained by the CEREALAB project and to integrate them with already existing data sources in order to create a tool for plant breeders and geneticists. The database can help them in unravelling the genetics of economically important phenotypic traits; in identifying and choosing molecular markers associated to key traits; and in choosing the desired parentals for breeding programs. The database is divided into three sub-schemas corresponding to the species of interest: wheat, barley and rice; each sub-schema is then divided into two sub-ontologies, regarding genotypic and phenotypic data, respectively. Database URL: http://www.cerealab.unimore.it/jws/cerealab.jnlp

Candidate gene expression profiling in two contrasting tomato cultivars under chilling stress

Tomato (Solanum lycopersicum Mill.) is sensitive to chilling stress during all stages of plant development. Genetic variation for chilling tolerance exists between cultivated tomato and its related wild species, but intra-specific variation has not been thoroughly investigated so far. Seedlings of 63 tomato accessions were evaluated under low temperature and two contrasting cultivars were identified for the trait: Albenga and San Marzano, the former being more chillingtolerant. To clarify the molecular mechanisms of chilling tolerance in tomato, changes in candidate gene expressions in the two tomato genotypes were analysed, using quantitative RT-PCR. Candidate genes were chosen among those known to be induced by chilling and/or with putative roles in CBF/DREB and ROS-mediated pathways. Results show that besides a CBF regulon, whose function is conserved, ROS and C2H2-type zinc finger protein-mediated cold signalling pathways were also involved in chilling tolerance. Under the chilling stress, the up-regulation of respective transcripts was consistently higher in the chilling-tolerant genotype than in the chilling-sensitive ones.

Copy number variation at the HvCBF4–HvCBF2 genomic segment is a major component of frost resistance in barley

A family of CBF transcription factors plays a major role in reconfiguring the plant transcriptome in response to low-freezing temperature in temperate cereals. In barley, more than 13 HvCBF genes map coincident with the major QTL FR-H2 suggesting them as candidates to explain the function of the locus. Variation in copy number (CNV) of specific HvCBFs was assayed in a panel of 41 barley genotypes using RT-qPCR. Taking advantage of an accurate phenotyping that combined Fv/Fm and field survival, resistance-associated variants within FR-H2 were identified. Genotypes with an increased copy number of HvCBF4 and HvCBF2 (at least ten and eight copies, respectively) showed greater frost resistance. A CAPS marker able to distinguish the CBF2A, CBF2B and CBF2A/B forms was developed and showed that all the higher-ranking genotypes in term of resistance harbour only CBF2A, while other resistant winter genotypes harbour also CBF2B, although at a lower CNV. In addition to the major involvement of the HvCBF4-HvCBF2 genomic segment in the proximal cluster of CBF elements, a negative role of HvCBF3 in the distal cluster was identified. Multiple linear regression models taking into account allelic variation at FR-H1/VRN-H1 explained 0.434 and 0.550 (both at p < 0.001) of the phenotypic variation for Fv/Fm and field survival respectively, while no interaction effect between CNV at the HvCBFs and FR-H1/VRN-H1 was found. Altogether our data suggest a major involvement of the CBF genes located in the proximal cluster, with no apparent involvement of the central cluster contrary to what was reported for wheat.

Genetic aspects of floral fragrance in plants.

It is generally assumed that compounds are emitted from flowers in order to attract and guide pollinators. Due to the invisibility and the highly variable nature of floral scent, no efficient and reliable methods to screen for genetic variation have been developed. Moreover, no convenient plant model systems are available for flower scent studies. In the past decade, several floral fragrance-related genes have been cloned; the biosynthesis and metabolic engineering of floral volatiles have been studied with the development of biotechnology. This review summarizes the reported floral fragrance-related genes and the biosynthesis of floral scent compounds, introduces the origin of new modification enzymes for flower scent, compares different methods for floral fragrance-related gene cloning, and discusses the metabolic engineering of floral scent. Finally, the perspectives and prospects of research on floral fragrance are presented.

IDENTIFICATION OF TOMATO GENES DIFFERENTIALLY EXPRESSED DURING COMPATIBLE INTERACTION WITH PYRENOCHAETA LYCOPERSICI

Breeding for resistance is the most effective tool for controlling the corky root disease of tomato caused by the fungus Pyrenochaeta lycopersici. However, little is known about the molecular bases of tomato-P. lycopersici interaction. In order to identify genes involved in the basal defence response activated in a susceptible cultivar and in disease symptom development, a set of cDNA-AFLP fragments derived from a profiling experiment was analysed. A total of 247 differentially expressed TDFs (transcript-derived fragments), identified as putative tomato genes, were characterized by similarity searches, and classified into 11 broad functional classes. Timings ranging between the early [48, 72 and 96 h post-infection (hpi)] and the late infection stages (20 and 27 dpi) were used. The changes of tomato root transcriptional profiles showed large differences in quantity and quality between the early and late stages of infection. Mechanisms of basal defence were most likely activated at early stages, when a gene coding for a receptor- like serine-threonine protein kinase and other genes of the signalling class were upregulated. At 20 dpi some of the mechanisms involved in defence were still activated, while at 27 dpi a general repression of gene expression was observed.

The CEREALAB Database: Ongoing Research and Future Challenges

The objective of the CEREALAB database is to help the breeders in choosing molecular markers associated to the most important traits. Phenotypic and genotypic data obtained from the integration of open source databases with the data obtained by the CEREALAB project are made available to the users. The first version of the CEREALAB database has been extensively used within the frame of the CEREALAB project. This paper presents the main achievements and the ongoing research related to the CEREALAB database. First, as a result of the extensive use of the CEREALAB database, several extensions and improvements to the web application user interface were introduced. Second, always derived from end-user needs, the notion of provenance was introduced and partially implemented in the context of the CEREALAB database. Third, we describe some preliminary ideas to annotate the CEREALAB database and to publish it in the Linking Open Data network.