Polyploidy plays an important role in plant adaptation to biotic and abiotic stresses. Alterations of the ploidy in grapevine plants regenerated via somatic embryogenesis (SE) may provide a source of genetic variability useful for the improvement of agronomic characteristics of crops. In the grapevine, the SE induction process may cause ploidy changes without alterations in DNA profile. In the present research, tetraploid plants were observed for 9.3% of ‘Frappato’ grapevine somatic embryos regenerated in medium supplemented with the growth regulators β-naphthoxyacetic acid (10 µM) and N⁶-benzylaminopurine (4.4 µM). Autotetraploid plants regenerated via SE without detectable changes in the DNA profiles were transferred in field conditions to analyze the effect of polyploidization. Different ploidy levels induced several anatomical and morphological changes of the shoots and mature leaves. Alterations have been also observed in stomata. The length and width of stomata of tetraploid leaves were 39.9 and 18.6% higher than diploids, respectively. The chloroplast number per guard cell pair was higher (5.2%) in tetraploid leaves. On the contrary, the stomatal index was markedly decreased (12%) in tetraploid leaves. The observed morphological alterations might be useful traits for breeding of grapevine varieties in a changing environment.

Plants produce considerable amounts of volatile organic compounds (VOCs) with several biological functions, including protection against biotic agents such as viruses and their vectors. In citrus species, these metabolites can be related with their different susceptibility/tolerance toward the Tristeza virus (CTV), one of the main biotic constraints for the citrus industry. The objective of this study was to compare the VOCs pattern from the leaves of a CTV-susceptible citrus variety such as Citrus aurantium and from three CTV-tolerant varieties: Citrus volkameriana, Carrizo citrange, and Forner-Alcaide no. 5. The VOCs emitted were analyzed via the headspace SPME method, while plant metabolites sequestered in the leaves were analyzed by heptane extraction followed by GC-MS. The results indicated that the majority of the VOCs emitted and sequestered in the leaves of the varieties tolerant and susceptible to CTV are constituted mainly by volatile terpenes (VTs) that exhibit strong qualitative/quantitative differences among the profiles of the four citrus species. In detail, the VOC emission indicated different patterns between C. aurantium and C. volkameriana and from both of them in comparison with Forner-Alcaide no. 5 and Carrizo citrange that exhibited more similarities, with the last two characterized by a higher presence of sesquiterpenes. The data obtained from the analysis of the VOCs sequestered in leaf tissues of the CTV-tolerant varieties indicated a higher presence of monoterpenes such as limonene, α-pinene, and p-cymene, known to be the main components of several plant extracts showing deterrent properties toward viruses and insect vectors. As VOC evaluation is a fast and noninvasive measure of phenotypic dynamics, allowing the association of plant phenotypes in accordance to plant disease resistance and/or stress tolerance, the possible implications of such differences in terms of tolerance grade to CTV and/or its related vectors are discussed.

O. ficus-indica (prickly pear cactus) is an important forage and food source in arid and semiarid ecosystems and is the most important cactus species in cultivation globally. The high degree of apomixis in the species is a hindrance in plant breeding programs where genetic segregation is sought for the selection of superior genotypes. To understand if in ovulo embryo rescue could increase the proportion of zygotic seedlings, we compared the mature seed-derived seedlings with those regenerated from in vitro embryo rescue at 20, 25, 30, 35, and 40 post-anthesis days (PADs) in four Italian cultivars. The seedlings were classified as apomictic or zygotic based on molecular marker analysis using inter-sequence single repeat (ISSR) primers. Multiple embryos were recovered from all the cultured immature ovules, and plantlets were regenerated and acclimatized to the field post hardening, with success rates ranging from 62% (‘Senza spine’) to 83% (‘Gialla’). The level of polyembryony differed among cultivars and recovery dates, with the highest being ‘Rossa’, producing 4.8 embryos/ovule at 35 PADs, and ‘Gialla’, the lowest, with 2.7 at 40 PADs. The maximum number of embryos observed within a single ovule was 14 in ‘Trunzara bianca’. ISSR analysis revealed that ovule culture at 35 PADs produced the highest percentage of zygotic seedlings in all the cultivars, from 51% (‘Rossa’) to 98% (‘Gialla’), with a high genotype effect as well. Mature seeds produced much fewer seedlings per seed, ranging from 1.2 in ‘Trunzara bianca’ to 2.0 in ‘Rossa’ and a lower percentage of zygotic seedlings (from 14% in ‘Rossa’ to 63% in ‘Gialla’). Our research opens a pathway to increase the availability of zygotic seedlings in O. ficus-indica breeding programs through in ovulo embryo culture.

This study is the first approach to in vitro asymbiotic germination of two species of Sicilian threatened terrestrial orchids, Anacamptis longicornu and Ophrys panormitana. Seeds were collected in the wild and cultured in two different media—Orchimax medium (OM) and Murashige and Skoog (MS)—and exposed to different photoperiods and temperatures to evaluate the best conditions for the specific stages of development. The germination of A. longicornu was very high on OM (95.5%) and lower on MS medium (21.4%), whereas O. panormitana germinated only on OM medium, with significantly lower percentages (12.0%), compared with A. longicornu. This difference is caused by variation in quality and quantity of nutrients used, primarily by nitrogen source. The results show that temperature and photoperiod widely affect seed germination and development. Although further investigations on asymbiotic and symbiotic germination are needed for the improvement of conservation of Mediterranean terrestrial orchids, our results contribute to the conservation of this group of plants.

Sansevieria Thunb. species are traditionally known as succulent ornamental plants worldwide. They are also cultivated for medicinal, fodder, soil conservation and fiber uses, and for their capacity to reduce environmental pollution. Sansevieria sexual propagation is limited by the lack of viable seeds, and reproduction is largely made via vegetative propagation by suckers or cuttings. For these reasons, genetic improvement by conventional breeding is limited. To overcome this problem and to address the increasing demand from customers for novel Sansevieria varieties, many commercial companies regularly use in vitro propagation, as is the case in the breeding process of several ornamental plants. In this paper, for the first time, we report a procedure for in vitro somatic embryogenesis and plant regeneration starting from three flower explants for seven different Sansevieria genotypes. Regeneration was attempted using stigmas/styles, anther/filament, and ovary which were cultured on a Murashige and Skoog solidified medium under three different plant growth regulator combinations. A good regeneration rate was obtained with all genotypes used under all culture conditions tested from every explant type, with percentages ranging from 0 to 73.3%. “Genetic stability” assessment of regenerated plants in respect to their mother plants was verified through flow cytometry analysis showing a high degree of uniformity, with only S. parva exhibiting a different level of DNA fluorescence among in vitro regenerated plants. This is an interesting achievement in the aim to produce true-to-type plants and new variants with desirable characteristics, both of which are desired features in ornamentals improvement.

The citrus tristeza virus (CTV) is an agent of devastating epidemics of the citrus plant grafted on Citrus aurantium, one of the main rootstocks still used in the Mediterranean area. Consequently, CTV-tolerant alternative citrus rootstocks are considered necessary to manage this disease and/or its vector; that in Mediterranean countries is the aphid Aphis gossypii. In this study, we analyzed the VOCs emitted from Citrus sinensis plants grafted on the CTV-susceptible C. aurantium and on the CTV-tolerant Volkamer lemon, Forner-Alcaide no. 5, and Carrizo citrange. Furthermore, the aphid preference/avoidance response toward these combinations was evaluated in a semi-field experiment. The VOC profiles recorded on the leaves of C. sinensis grafted on the four rootstocks listed above showed significant differences in the abundances and ratios of the compounds emitted. The behavioral experiments indicated that A. gossypii prefers to orient and establish on the C. sinensis plants grafted on C. aurantium rather than on that grafted on the three CTV-tolerant varieties. The possibility that this avoidance mechanism is triggered by the different profile of the VOC emitted by the different combinations and the consequent susceptibility/tolerance shown toward CTV is discussed.