The success of in vitro plant regeneration and the competence of genetic transformation greatly depends on the genotype of the species of interest. In previous work, we developed a method for the efficient Agrobacterium-mediated genetic transformation via organogenesis of V. vinifera cultivar Thompson Seedless, by using meristematic bulk (MB) as starting tissue. In this study, we applied this method for the regeneration and transformation of MBs obtained from the Italian cultivar Ciliegiolo and two of the commonly used Vitis rootstocks, 110 Richter and Kober 5BB, in comparison with Thompson Seedless. The A. tumefaciens strain EHA105, harbouring pK7WG2 binary vector, was used for the transformation trials, which allowed selection through the enhanced-green fluorescent protein (eGFP) and the neomycin phosphotransferase (nptII) gene. Putative transformed tissues and/or shoots were identified by either a screening based on the eGFP expression alone or its use in combination with kanamycin in the medium. MBs obtained from Thompson Seedless showed the highest regeneration and transformation cell competence, which subsequently allowed the recovery of stably transformed plants. Ciliegiolo, 110 Richter, and Kober 5BB, produced actively growing transgenic calli showing eGFP fluorescence, more consistently on selective media, but had no regenerative competence.

Background: Efficient transformation and regeneration methods are a priority for successful application of genetic engineering to vegetative propagated plants such as grape. The current methods for the production of transgenic grape plants are based on Agrobacterium-mediated transformation followed by regeneration from embryogenic callus. However, grape embryogenic calli are laborious to establish and the phenotype of the regenerated plants can be altered.

Background Magnesium (Mg) deficiency causes physiological and molecular responses, already dissected in several plant species. The study of these responses among genotypes showing a different tolerance to the Mg shortage can allow identifying the mechanisms underlying the resistance to this nutritional disorder. To this aim, we compared the physiological and molecular responses (e.g. changes in root metabolome and transcriptome) of two grapevine rootstocks exhibiting, in field, different behaviors with respect to Mg shortage (1103P, tolerant and SO4 susceptible). Results The two grapevine rootstocks confirmed, in a controlled growing system, their behavior in relation to the tolerance to Mg deficiency. Differences in metabolite and transcriptional profiles between the roots of the two genotypes were mainly linked to antioxidative compounds and the cell wall constituents. In addition, differences in secondary metabolism, in term of both metabolites (e.g. alkaloids, terpenoids and phenylpropanoids) and transcripts, assessed between 1103P and SO4 suggest a different behavior in relation to stress responses particularly at early stages of Mg deficiency. Conclusions Our results suggested that the higher ability of 1103P to tolerate Mg shortage is mainly linked to its capability of coping, faster and more efficiently, with the oxidative stress condition caused by the nutritional disorder. Electronic supplementary material The online version of this article (10.1186/s12870-019-1726-x) contains supplementary material, which is available to authorized users.

In different countries, mostly in EU, rules for strawberry nursery propagation impose the use of micropropagation only to produce stock virus free plant followed by at least three nursery production cycles in the field before selling these plants to growers. This limit has been imposed by problems concerning true-to-type plants observed in micro-propagated plants of some cultivars, with higher genotypic and phenotypic instability, and the incorrect use of higher concentrations of cytokinin in the proliferation phase. This production system of certified plants has high economic and environmental costs without a final guarantee on the sanitary state of the plants. New knowledges on in vitro techniques and new cultivars with higher genetic stability can offer the opportunity to improve the use of micropropagation in strawberry nursery industry. With the aim to propose a new protocol for strawberry propagation, an experimental trial was set up to compare the behavior of frigo and micro-mother plants of cv. Alba, a well know commercial cultivar in EU, in two cycles of nursery runner production and the yield, to verify in two successive cycles the fruit quality of daughter plants grown in open field conditions. The results confirmed the equivalence of the two types of mother plants both in plant nursery production and subsequently in field fruit production. Therefore, the direct use of micro-mother plants for nursery productions of frigo-plants for growers offer an alternative option for large scale frigo-plant nursery production.

Until now, the application of genetic transformation techniques in peach has been limited by the difficulties in developing efficient regeneration and transformation protocols. Here we describe an efficient regeneration protocol for the commercial micropropagation of GF677 rootstock (Prunus persica × Prunus amygdalus). The method is based on the production, via organogenesis, of meristematic bulk tissues characterized by a high competence for shoot regeneration. This protocol has also been used to obtain GF677 plants genetically engineered with an empty hairpin cassette (hereafter indicated as hp-pBin19), through Agrobacterium tumefaciens-mediated transformation. After 7-8 months of selection on media containing kanamycin, we obtained two genetically modified GF677 lines. PCR and Southern blot analyses were performed to confirm the genetic status.