Expression profile analysis of early fruit development in iaaM-parthenocarpic tomato plants

<p>Abstract</p> <p>Background</p> <p>Fruit normally develops from the ovary after pollination and fertilization. However, the ovary can also generate seedless fruit without fertilization by parthenocarpy. Parthenocarpic fruit development has been obtained in tomato (<it>Solanum lycopersicum</it>) by genetic modification using auxin-synthesising gene(s) (<it>DefH9-iaaM</it>; <it>DefH9-RI-iaaM</it>) expressed specifically in the placenta and ovules.</p> <p>Findings</p> <p>We have performed a cDNA Amplified Fragment Length Polymorphism (cDNA-AFLP) analysis on pre-anthesis tomato flower buds (0.5 cm long) collected from <it>DefH9-iaaM </it>and <it>DefH9-RI-iaaM </it>parthenocarpic and wild-type plants, with the aim to identify genes involved in very early phases of tomato fruit development. We detected 212 transcripts differentially expressed in auxin-ipersynthesising pre-anthesis flower buds, 65 of them (31%) have unknown function. Several differentially expressed genes show homology to genes involved in protein trafficking and protein degradation via proteasome. These processes are crucial for auxin cellular transport and signaling, respectively.</p> <p>Conclusion</p> <p>The data presented might contribute to elucidate the molecular basis of the fruiting process and to develop new methods to confer parthenocarpy to species of agronomic interest. In a recently published work, we have demonstrated that one of the genes identified in this screening, corresponding to #109 cDNA clone, regulates auxin-dependent fruit initiation and its suppression causes parthenocarpic fruit development in tomato.</p

Hybrids and allied species as potential rootstocks for eggplant: Effect of grafting on vigour, yield and overall fruit quality traits

Grafting of fruiting vegetables is an effective technique to overcome pests and diseases in modern cropping systems and it is often used to improve yield and fruit quality. Eggplant is an important vegetable crop that benefits significantly from grafting. In this regards, the exploitation, valorization and breeding of new rootstock genotypes as possible substitute to those commonly used (Solanum torvum and tomato hybrids) would permit an intensive eggplant crop system in those situations where a rootstock rotation is required. In the present article, we study the effects of several potential rootstocks including both wild/allied species of eggplant [S. torvum (STO), S. macrocarpon (SMA), S. aethiopicum (accession SASI), S. aethiopicum (accession SASa2), S. paniculatum (jurubeba) (SPA) and S. indicum (SIN)] and Msa 2/2 E7 and 460 CAL. eggplant hybrids on plant vigor, yield and fruit characteristics of eggplant F1 hybrid (‘Birgah’), in two spring-summer growing seasons (2014 and 2015). SPA and the hybrids Msa 2/2 E7 and 460 CAL. displayed a high percentage of grafting success. ‘Birgah’ scion grafted onto the two above-mentioned rootstocks showed a notable vigour and yield. Both rootstocks did not promote any unfavorable effects on apparent fruit quality traits and overall fruit composition. Furthermore, the concentration of glycoalkaloids in the fruit remained below the recommended safety value (200 mg/100 g of dw). These results suggest that SPA and Msa 2/2 E7 and 460 CAL. eggplant hybrids might represent a potential rootstock alternative to S. torvum

The Population Structure and Diversity of Eggplant from Asia and the Mediterranean Basin.

A collection of 238 eggplant breeding lines, heritage varieties and selections within local landraces provenanced from Asia and the Mediterranean Basin was phenotyped with respect to key plant and fruit traits, and genotyped using 24 microsatellite loci distributed uniformly throughout the genome. STRUCTURE analysis based on the genotypic data identified two major sub-groups, which to a large extent mirrored the provenance of the entries. With the goal to identify true-breeding types, 38 of the entries were discarded on the basis of microsatellite-based residual heterozygosity, along with a further nine which were not phenotypically uniform. The remaining 191 entries were scored for a set of 19 fruit and plant traits in a replicated experimental field trial. The phenotypic data were subjected to principal component and hierarchical principal component analyses, allowing three major morphological groups to be identified. All three morphological groups were represented in both the "Occidental" and the "Oriental" germplasm, so the correlation between the phenotypic and the genotypic data sets was quite weak. The relevance of these results for evolutionary studies and the further improvement of eggplant are discussed. The population structure of the core set of germplasm shows that it can be used as a basis for an association mapping approach

Optimization of transgene action at the post-transcriptional level: high quality parthenocarpic fruits in industrial tomatoes

Background: Genetic engineering of parthenocarpy confers to horticultural plants the ability toproduce fruits under environmental conditions that curtail fruit productivity and quality. TheDefH9-iaaM transgene, whose predicted action is to confer auxin synthesis specifically in theplacenta, ovules and derived tissues, has been shown to confer parthenocarpy to several plantspecies (tobacco, eggplant, tomato) and varieties.Results: UC82 tomato plants, a typical cultivar used by the processing industry, transgenic for theDefH9-iaaM gene produce parthenocarpic fruits that are malformed. UC82 plants transgenic forthe DefH9-RI-iaaM, a DefH9-iaaM derivative gene modified in its 5'ULR by replacing 53 nucleotidesimmediately upstream of the AUG initiation codon with an 87 nucleotides-long sequence derivedfrom the rolA intron sequence, produce parthenocarpic fruits of high quality. In an in vitro translationsystem, the iaaM mRNA, modified in its 5'ULR is translated 3\u20134 times less efficiently than theoriginal transcript. An optimal expressivity of parthenocarpy correlates with a reduced transgenemRNA steady state level in DefH9-RI-iaaM flower buds in comparison to DefH9-iaaM flower buds.Consistent with the known function of the iaaM gene, flower buds transgenic for the DefH9-RI-iaaMgene contain ten times more IAA than control untransformed flower buds, but five times less thanDefH9-iaaM flower buds.Conclusions:: By using an auxin biosynthesis transgene downregulated at the post-transcriptionallevel, an optimal expressivity of parthenocarpy has been achieved in a genetic background notsuitable for the original transgene. Thus, the method allows the generation of a wider range ofexpressivity of the desired trait in transgenic plants

Identification of a new R3 MYB type repressor and functional characterization of the members of the MBW transcriptional complex involved in anthocyanin biosynthesis in eggplant (S. Melongena L.)

Here we focus on the highly conserved MYB-bHLH-WD repeat (MBW) transcriptional complex model in eggplant, which is pivotal in the transcriptional regulation of the anthocyanin biosynthetic pathway. Through a genome-wide approach performed on the recently released Eggplant Genome (cv. 67/3) previously identified, and reconfirmed by us, members belonging to the MBW complex (SmelANT1, SmelAN2, SmelJAF13, SmelAN1) were functionally characterized. Furthermore, a regulatory R3 MYB type repressor (SmelMYBL1), never reported before, was identified and characterized as well. Through a qPCR approach, we revealed specific transcriptional patterns of candidate genes in different plant tissue/organs at two stages of fruit development. Two strategies were adopted for investigating the interactions of bHLH partners (SmelAN1, SmelJAF13) with MYB counterparts (SmelANT1, SmelAN2 and SmelMYBL1): Yeast Two Hybrid (Y2H) and Bimolecular Fluorescent Complementation (BiFC) in A. thaliana mesophylls protoplast. Agro-infiltration experiments highlighted that N. benthamiana leaves transiently expressing SmelANT1 and SmelAN2 showed an anthocyanin-pigmented phenotype, while their co-expression with SmelMYBL1 prevented anthocyanin accumulation. Our results suggest that SmelMYBL1 may inhibits the MBW complex via the competition with MYB activators for bHLH binding site, although this hypothesis requires further elucidation

A new intra-specific and high-resolution genetic map of eggplant based on a ril population, and location of QTLS related to plant anthocyanin pigmentation and seed vigour

Eggplant is the second most important solanaceous berry-producing crop after tomato. Despite mapping studies based on bi-parental progenies and GWAS approaches having been performed, an eggplant intraspecific high-resolution map is still lacking. We developed a RIL population from the intraspecific cross &lsquo;305E40&rsquo;, (androgenetic introgressed line carrying the locus Rfo-Sa1 conferring Fusarium resistance) x &lsquo;67/3&rsquo; (breeding line whose genome sequence was recently released). One hundred and sixty-three RILs were genotyped by a genotype-by-sequencing (GBS) approach, which allowed us to identify 10,361 polymorphic sites. Overall, 267 Gb of sequencing data were generated and ~773 M Illumina paired end (PE) reads were mapped against the reference sequence. A new linkage map was developed, including 7249 SNPs assigned to the 12 chromosomes and spanning 2169.23 cM, with iaci@liberoan average distance of 0.4 cM between adjacent markers. This was used to elucidate the genetic bases of seven traits related to anthocyanin content in different organs recorded in three locations as well as seed vigor. Overall, from 7 to 17 QTLs (at least one major QTL) were identified for each trait. These results demonstrate that our newly developed map supplies valuable information for QTL fine mapping, candidate gene identification, and the development of molecular markers for marker assisted selection (MAS) of favorable alleles