Tomato ionomic approach for food fortification and safety.

Food fortification is an issue of paramount of importance for people living both in developed and in developing countries. Among substances listed as "nutriceuticals", essential minerals have been recognised for their involvement in several healthy issues, involving all ages. In this frame, food plants are playing a pivotal role since their capability to compartmentalise ions and proteinmetal complexes in edible organs. Conversely, the accumulation of high metal levels in those organs may lead to safety problems. In the recent years, thanks to the availability of new and improved analytical apparatus in both ionic and genomic/transcrittomics areas, it is became feasible to couple data coming from plant physiology and genetics. Ionomics is the discipline that studies the cross-analysis of both data sets. Our group, in the frame of GenoPom project granted by MiUR, is interested to study the ionomics of tomatoes cultivars derived by breeding programmes in which wild relatives have been used to transfer several useful traits, such as resistance to biotic or abiotic stresses, fruit composition and textiture, etc. The introgression of the wild genome into the cultivated one produces new gene combinations. They might lead to the expression of some traits, such as increased or reduced adsorption of some metals and their exclusion or loading into edible organs, thus strongly involving the nutritional food value. Our final goal is to put together data coming from ions homeostasis and gene expression analyses, thus obtaining an ionomic tomato map related to ions absorption, translocation and accumulation in various plant organs, fruits included. To follow our hypothesis, we are studying the ionome of Solanum lycopersicum cv. M82 along with 76 Introgression Lines (ILs) produced by interspecific crosses between this cultivar and the wild species S. pennellii. These ILs are homozygous for small portions of the wild species genome introgressed into the domesticated M82 one. They are used as a useful tool for mapping QTL associated with many traits of interest. It is worthy to note that, until now, little information is available on QTL for ions accumulation in tomato. Moreover, as our knowledge, effects of new gene combinations in introgressed lines on ions uptake related to food safety have not been extensively studied. In this presentation we show results coming from the ionome analysis, carried out on S . lycopersicum M82 and several ILs. Plants were grown in pots in a greenhouse and watered with deionised water Thirty day-old plants were left to grow for 15 days in the presence of non-toxic concentration of Cd, Pb, As, Cr and Zn given combined. Leaves of all plants were then harvested and stored at -80°C for ionome and gene expression analyses. Preliminary results of ionome analysis of S. lycopersicum M82 and several ILs, carried out using an ICP-MS, showed that traits correlated to toxic metals and micronutrients accumulation in apical leaves were significantly modified in response to specific genetic backgrounds. Those results are perhaps due to the introgression of traits linked to uptake, translocation and accumulation of useful and/or toxic metal into plant apical leaves and to interactions of the wild type introgressed genomic regions with the cultivated genome. Also, data are shown on the identification and isolation of Solanum gene sequences related to ions uptake, translocation and accumulation, useful for further real-time gene expression evaluation in both cultivated and ILs during the treatments with the above-mentioned metals

Enhancing Sustainability by Improving Plant Salt Tolerance through Macro- and Micro-Algal Biostimulants

Algal biomass, extracts, or derivatives have long been considered a valuable material to bring benefits to humans and cultivated plants. In the last decades, it became evident that algal formulations can induce multiple effects on crops (including an increase in biomass, yield, and quality), and that algal extracts contain a series of bioactive compounds and signaling molecules, in addition to mineral and organic nutrients. The need to reduce the non-renewable chemical input in agriculture has recently prompted an increase in the use of algal extracts as a plant biostimulant, also because of their ability to promote plant growth in suboptimal conditions such as saline environments is beneficial. In this article, we discuss some research areas that are critical for the implementation in agriculture of macro- and microalgae extracts as plant biostimulants. Specifically, we provide an overview of current knowledge and achievements about extraction methods, compositions, and action mechanisms of algal extracts, focusing on salt-stress tolerance. We also outline current limitations and possible research avenues. We conclude that the comparison and the integration of knowledge on the molecular and physiological response of plants to salt and to algal extracts should also guide the extraction procedures and application methods. The effects of algal biostimulants have been mainly investigated from an applied perspective, and the exploitation of different scientific disciplines is still much needed for the development of new sustainable strategies to increase crop tolerance to salt stress

SOLANUM LYCOPERSICUM X S. PENNELLII INTROGRESSION LINES WERE USEFUL TO CHARACTERISE THE IONOME OF TOMATO FRUIT

In the frame of "GenoPom" PON-MIUR project, we have began a study of tomato ionome in order to identify the contribution of specific chromosome and part of them on the ionome. For this purpose, we have analysed by ICP-MS plants of an introgression line (IL) population derived from the cross between Solanum lycopersicum cv. M82 and S. pennellii (Eshed and Zamir, 1995) grown under controlled environmental conditions.we report results derived from tomato whole fruits ionome analysis of 30 IL, covering all 12 tomato chromosomes, along with the recurrent parent cv. M82. Among several detected elements, the following ones have firstly been analysed: Ca, Fe, Cu, Zn and Se. Each element concentration data were referred to cv. M82

De Novo Transcriptome Assembly of Cucurbita Pepo L. Leaf Tissue Infested by Aphis Gossypii

Zucchini (Cucurbita pepo L.), extensively cultivated in temperate areas, belongs to the Cucurbitaceae family and it is a species with great economic value. One major threat related to zucchini cultivation is the damage imposed by the cotton/melon aphid Aphis gossypii Glover (Homoptera: Aphididae). We performed RNA-sequencing on cultivar "San Pasquale" leaves, uninfested and infested by A. gossypii, that were collected at three time points (24, 48, and 96 h post infestation). Then, we combined all high-quality reads for de novo assembly of the transcriptome. This resource was primarily established to be used as a reference for gene expression studies in order to investigate the transcriptome reprogramming of zucchini plants following aphid infestation. In addition, raw reads will be valuable for new experiments based on the latest bioinformatic tools and analytical approaches. The assembled transcripts will serve as an important reference for sequence-based studies and for primer design. Both datasets can be used to support/improve the prediction of protein-coding genes in the zucchini genome, which has been recently released into the public domain

Ion uptake and YSL1 gene identification in tomato

Tomato breeder are using wild tomato relatives, even non-cross compatibles ones, in order to obtain cultivars with highly commercial values bearing new traits. However, the introgression of a wild genome into the cultivated one produces a new gene combinations that may lead to the expression of undeliverable traits, perhaps not so easy to recognise; even more, phenotypic variations may escape during the selection procedure when minor genes or non-abnormal phenotypes are involved. In the frame of the “GenoPom” project funded by MIUR, we have focused our interest on the alteration of heavy metals uptake from the soil and their loading into edible organs in commercial lines coming from Solanum interspecific crosses. Our final aim is to put together data coming from ion homeostasis and gene expression analyses, thus obtaining a ionomic map of tomato. To pursue our goal, we have started to study the cv M82 of Solanum lycopersicon, the wild relative Solanum pennelli and their introgression lines IL. Regarding the experiments on ion homeostasis, S. lycopersicon M82 and the introgression line IL 6-4-2 were grown in hydroponics under controlled environmental conditions. Twenty day-old plants were left to grow for 10 days in the presence of non-toxic concentration of Cd (10 mM), Pb (3 mM), Zn (100 mM) given separately or combined. Control and treated roots and leaves were then harvested and stored at -80°C for ionic and gene expression analyses. Ions analysis of Solanum lycopersicon M82 and IL 6-4-2 showed that traits correlated to ionic homeostasis is significantly modified in response to all metals and to the genotype. The analysis of ions data, obtained by ICP-MS, give a pictures of the different responses performed both to different stress and to combined stress, probably correlated to the up-regulation and/or down regulation of metal uptake proteins. Performed experiments demonstrate that the introgression of the wild genome into the cultivated one produces a new phenotype, perhaps due to the expression of traits linked to uptake, translocation and accumulation of useful and/or toxic metal into plant tissues and organs. Regarding the functional genomics approach for gaining insight into gene networks involved in mineral-ion accumulation in tomato plants, in literature has been reported that at least 25 major family genes are involved for metal homeostasis in plants. Among them, the genes ysl, hma, mtp, znt, zrt have been already studied at least in the plant species Arabidopsis thaliana, A. halleri and Thlaspi caerulescens. So far, no such genes have been reported to be cloned in Solanum species. We have focused our study on the genes YSL1, ZNT1 and MTP1 responsible for uptake, translocation and accumulation of metal such as zinc, cadmium, and iron into plant compartment. For all of them, consensous sequences from nucleotide multialignment have been obtained. Then, each of those were blasted in a Solanum EST collection databank and an assembled UniGene sequence was obtained.. Finally, we have designed primers and performed PCR analysis on S. lycopersicon and S. pennelli genomic DNA. So far, we have cloned a putative ysl1 sequence from tomato, that has shown that a very high percentage of identity (92%) with whole ysl1 gene of Nicotiana tabacum; the in silico translated sequence of this sequence has shown a 89% of identity with the same tobacco protein

High AN1 variability and interaction with basic helix-loop-helix co-factors related to anthocyanin biosynthesis in potato leaves

AN1 is a regulatory gene that promotes anthocyanin biosynthesis in potato tubers and encodes a R2R3 MYB transcription factor. However, no clear evidence implicates AN1 in anthocyanin production in leaves, where these pigments might enhance environmental stress tolerance. In our study we found that AN1 displays intraspecific sequence variability in both coding/non-coding regions and in the promoter, and that its expression is associated with high anthocyanin content in leaves of commercial potatoes. Expression analysis provided evidence that leaf pigmentation is associated to AN1 expression and that StJAF13 acts as putative AN1 co-regulator for anthocyanin gene expression in leaves of the red leaf variety "Magenta Love", while a concomitant expression of StbHLH1 may contribute to anthocyanin accumulation in leaves of "Double Fun". Yeast two-hybrid experiments confirmed that AN1 interacts with StbHLH1 and StJAF13 and the latter interaction was verified and localized in the cell nucleus by bimolecular fluorescence complementation assays. In addition, transgenic tobacco (Nicotiana tabacum) overexpressing a combination of either AN1 with StJAF13 or AN1 with StbHLH1 showed deeper purple pigmentation with respect to AN1 alone. This further confirmed AN1/StJAF13 and AN1/StbHLH1 interactions. Our findings demonstrate that the classical loci identified for potato leaf anthocyanin accumulation correspond to AN1 and may represent an important step to expand our knowledge on the molecular mechanisms underlying anthocyanin biosynthesis in different plant tissues. This article is protected by copyright. All rights reserved