Drought negatively affects plants by altering morphological, physiological and metabolic processes and ultimately reducing yields. Garlic (Allium sativum L.), an important member of the Alliaceae family, is also sensitive to drought and maximizing the yield of garlic bulbs is largely dependent on water availability. The objective of this study was to determine the effects of drought stress on morphological and physiological characteristics, as well as on phenolic, sugar, inulin and free amino acid content and antioxidant activity in two Croatian garlic ecotypes, ‘Istarski crveni’ (IC) and Istarski bijeli (IB). Drought was induced by using polyethylene glycol 8000 (PEG) solution (−0.6 MPa) starting 21 days after clove planting and lasted for 20 days. Drought reduced plant height, number of leaves and plant weight, but increased root length in both ecotypes compared to the control treatment. Among the physiological parameters, significant differences were observed between the two ecotypes studied in the spectral characteristics of the leaves, namely reflection in red, green and blue, VAL, values of the vegetation indices related to the chlorophyll content (CHI, GI), and the anthocyanin content (ARI). Ecotype IC showed higher antioxidant activity in the control treatment due to higher total phenolic content (TPC), but under drought conditions higher DPPH radical scavenging activity was determined in ecotype IB and higher values of FRAP in IC. Sucrose and glucose generally decreased under drought, while inulin increased in IB but decreased in IC. Total free amino acid content increased under drought in both ecotypes. In conclusion, drought tolerance of IB might be associated with increased accumulation of inulin and higher levels of amino acids, especially those shown to contribute to drought resistance. In IC, drought tolerance is associated with an increase in some amino acid compounds and better root growth in depth, probably due to a more efficient translocation of sucrose to the underground part of the plant.

In vitro plants that are free of pathogens are crucial for biotechnological breeding methods. The present study investigates the effects of sterilization with sodium hypochlorite (NaClO) and the addition of Plant Preservative Mixture (PPM^TM) to the growth medium on pathogen elimination, germination, and seedling development of the winter wheat (Triticum aestivum L.) variety Mara. The sterilization treatments differed in the duration of seed sterilization in 4% NaClO and the PPM concentration added to the growth medium. Pathogenic fungi of the genera Aspergillus, Cladosporium, Penicillium, and Bipolaris were completely eliminated when the seeds were sterilized in NaClO and placed on growth media with the addition of PPM. Extending the duration of the sterilization treatment with NaClO to 50 min reduced Fusarium contamination, while the interaction between the 50 min sterilization treatment with NaClO and the addition of PPM to the growth medium reduced Alternaria contamination. Our results suggest that PPM could complement sterilization procedures with NaClO in the introduction of highly infected wheat seeds in vitro. Seed germination was not affected by sterilization with NaClO or by the addition of PPM. However, PPM at a concentration of 4 mL L⁻¹ had a negative effect on seedling development.

The present study was conducted to establish a protocol for the regeneration of virus-free garlic plants through somatic embryogenesis of two Croatian garlic ecotypes. Basal parts of cloves from mother plants were cultured on a full Murashige and Skoog (MS) or modified MS medium (¼ of KNO₃ and NH₄NO₃ and 2xMgSO₄) containing 0.1 mg L⁻¹ 2,4-dichlorophenoxyacetic acid (2,4-D) or 1 mg L⁻¹ 2,4-D + 0.5 mg L⁻¹ kinetin (Kin) and representing four different treatments. Plants were regenerated in MS medium containing 0.1 mg L⁻¹ 2,4-D and rooted in a medium containing 0.05 mg L⁻¹ 1-naphthaleneacetic acid (NAA) + 0.005 mg L⁻¹ 6-(γ,γ-dimethylallylamino)purine (2iP). The presence of viruses (i.e., sanitary status) of the mother plants and regenerants was checked by enzyme-linked immunosorbent assay (ELISA) and reverse transcription-polymerase chain reaction (RT-PCR). The mother plants were infected with onion yellow dwarf virus (OYDV) and leek yellow stripe virus (LYSV). In addition, the presence of garlic common latent virus (GCLV) was confirmed in four mother plants. Embryogenic callus developed in all four treatments with success ranging from 55% to 81% depending on treatment and ecotype. Plant conversion was significantly higher in somatic embryos developed in media containing 0.1 mg L⁻¹ 2,4-D than those developed in media containing 1 mg L⁻¹ 2,4-D + 0.5 mg L⁻¹ Kin. Virus elimination success ranged from 13.3% up to 62.5% depending on garlic ecotype and treatment. The overall rate of virus elimination by somatic embryogenesis for both treatments and ecotypes were 20.7%, 22.9%, and 30.5% for OYDV, GCLV, and LYSV, respectively. Based on these results, somatic embryogenesis has been shown to be equally or more successful in eliminating garlic viruses compared to other in vitro methods.

Caper (Capparis orientalis Veill.) is a species rich in bioactive compounds, with positive effects on human health. It has a great adaptability to harsh environments and an exceptional ability to extract water from dry soils. In Croatia, the caper grows as a wild plant, and its cultivation is insignificant, which is probably due to propagation difficulties. Micropropagation could be a solution for this. The aim of this study was to investigate the success of the micropropagation, in vitro rooting, and acclimatization of Capparis orientalis Veill. Shoot proliferation was tested in a Murashige and Skoog (MS) medium, with sucrose or glucose, and in 13 treatments, presenting the combined effect of different cytokinins and their concentrations. The success of rooting was examined in relation to the impact of various auxins, durations of rooting, and carry-over effects. A better proliferation was achieved when sucrose was used. The highest number (18) of shoots/explants was obtained in the medium supplemented with 0.6 mg·L⁻¹ meta-topolin, while the rooting was equally efficient in the media supplemented with 2 mg·L⁻¹ of indole-3-acetic acid or indole-3-butyric acid, or in hormone-free rooting medium. A prolonged time in the media increased the rooting efficiency, while the carry-over effect had no influence. The acclimatization rate reached 66%. Additional efforts should be made to find out how to speed upthe rooting and enhance the acclimatization rate of caper grown in Croatia.

Viruses are responsible for more than 50% of annual potato tuber yield losses and cause great economic damage. The traditional Croatian potato cultivar ‘Brinjak’ is important for local growers because of its economically profitable production and as a gene pool for future breeding programs. However, the full genetic potential of the cultivar cannot be exploited due to virus infection. In this study, we attempted to eliminate potato virus M (PVM) and potato virus S (PVS) from potato cultivar ‘Brinjak’ and to evaluate the effects on physiological parameters and yield. Shoot apices were isolated from PVM + PVS-infected sprouts and cultivated for six weeks on MS medium with the addition of 50 or 100 mg L⁻¹ ribavirin. The surviving shoot apices were micropropagated. The in vitro post-eradication period lasted 200 days. DAS-ELISA and RT-PCR were performed on R0 and R1 plants 90 days after acclimatization to determine the sanitary status of the plants. Chlorophyll fluorescence and multispectral imaging were performed on the R0 plants at the same time. The success of PVS elimination was 33% at both ribavirin concentrations. However, neither concentration was successful in eliminating PVM. Plants with mixed infection (PVM + PVS) had more severe disease symptoms compared to PVM-infected plants, affecting photochemistry and multispectral parameters and, consequently, yield. PVM + PVS plants had significantly lower number and weight of tubers per plant and lower average tuber weight than plants with single PVM infection in most of the generations studied. The results indicate a strong negative impact of PVS in mixed infections with PVM and show the importance of its elimination from potato plants.