RESPONSES OF SOME NEW ROMANIAN POTATO VARIETIES TO THE IN VITRO HIDRIC STRESS

Plant performance and crop yield are negatively affected by drought and heat in the context of the global climate changes. The present study was carried out to the National Institute for Research and Development Brasov, Romania, to observe the tolerance of three potato varieties to in vitro water stress. In vitro water stress negatively affects leaf size and number, number of internodes, stem and root length.Microbuts resulting from uninodal segmentation of in vitro-developed plantlets were inoculated into tubes containing Murashige-Skoog medium, enriched with naphthyl acetic acid and 20 g / l sugar and various amounts of agar.A high reduction of morphological parameters was observed to Castrum variety, susceptible for water deficit, while Ervant variety is more tolerant to drought than the other two varieties. The results indicated that simulation of drought stress under in vitro conditions constitutes a convenient way to study the drought effects on potato plants

The incidence of Mop-Top and Aucuba potato viruses in several Romanian areas (preliminary studies)

PMTV (Potato Mop-Top Virus ) an PAMV (Potato Aucuba Mosaic Virus) are new Romanian damaging pathogens of potato crop. They can cause serious reduced yield and decrease of the tuber’s quality. In case of these viruses, infected plants do not allways show symptoms and symptom depends on potato cultivar, virus strain and the environment. PMTV and PAMV infection of material plants can produce spraing in tubers of sensitive varieties. PMTV cause heavy losses in northen Europe and it is very difficult to control. Foliar symptoms include bright yellow blotch (Aucuba), a ’V’-shaped yellow pattern, deformed leaves and internode shortening. PAMV is a helping virus for devlopment of dangerous potyvirus like Potato Virus Y (PVY). Elimination of all these pathogens from potato supply is essential for potato production and the choice of resistant varieties to the infection with these viruses could be one of the measures recommended for farmers and producers. The results of this preliminary study show that PMTV and PAMV were not found in the material collected from the following varieties: Armonia, Azaria, Christian, Cosiana and Millenium (samples collected from the counties Braşov, Covasna, Harghita, Suceava in 2019 and 2020)

Optimization of sweet potato (Ipomoea batatas L.) in vitro cultivation by using the contaminated cultures for obtaining new shoots in greenhouse conditions

The artificial media used for plant tissue cultures contains numerous nutrients that can create favorable conditions for the development of pathogens. As antibiotic use is not encouraged, a new strategy has been tried to reduce the losses caused by the presence of microbial infections in "in vitro" cultivation of sweet potato. This consisted in the transplantation in greenhouse conditions of sweet potato plantlets from contaminated "in vitro" cultures, in order to obtain new shoots. Five sweet potato varieties were used in this study, and two types of substrate for planting: pearlite and a mixture of peat and pearlite (1:1). The survival rate of the plantlets was 100% on the substrate consisting only of pearlite. The surviving sweet potato plants had a rapid growth rate, the greenhouse conditions being favorable for this culture. Approximately two months after transplantation, the obtained shoots could be used as a source of explants to initiate new "in vitro" cultures. Regarding the number of shoots the highest value was obtained by the Yulmi variety. The length of the shoots varied according to the variety, thus the highest value was recorded by the KSC1 variety (98.30 cm) . The number of buds/shoot is strongly influenced by the variety. In some sweet potato varieties the distance between buds is smaller, and in others larger, this being a characteristic of the variety. Regarding this trait the best results were obtained in Juhwangmi variety. By applying this method, the process of sweet potato "in vitro" multiplication becomes more economically efficient. After only a few weeks under greenhouse conditions, involving minimal costs, many shoots can be obtained

In vitro selection of true potato seed genotypes tolerant to drought stress

The biological material used in this study was produced from true potato seed (TPS). Nine genotypes (MIL19-01-08, MIL19-01-22, MIL19-01-37, ZIL19-02-01 , ZIL19-02-11, ZIL19-02-43, GIL19-03-07, GIL19-03-29 and GIL19-03-38) were tested in vitro for drought tolerance. Four treatments were used to induce in vitro water stress: MS medium with three different concentrations of PEG (1%, 1.5%, 2%) and one variant of MS medium without PEG as control. On culture medium variant with highest concentration of PEG (2%) GIL19-03-29 obtained best results for plantlet height (11.08 cm), leaf number (9.50), root number (5.33), fresh plant weight (0.167 g). In stress conditions GIL19-03-07 recorded best results for plant fresh weight (0.173 g), root length (7.17 cm), plantlet height (12.28 cm) on PEG 1%. Also, ZIL19-02-43 obtained higher values on the culture medium variants with the highest level of water stress for parameters such as root fresh weight (0.146 g), plant fresh weight (0.163 g), root length (7.08 cm) on PEG 1.5%. The potato genotypes GIL19-03-29, GIL19-03-07 and ZIL19-02-43 showed the best tolerance to the water deficit and were selected for further assessments both in protected area (greenhouse) and open-field conditions

Researches regarding the minitubers production from potato lines

In this study was done researches about minitubers production from 14 potato lines studied: TS 12-1488-1574, TS 12- 1489-1574, TS 12-1497-1573, TS 11-1475-1633, TS 12-1502-1675, TS 11-1472-1633, TS 11-1468-1633, TS 09-1441- 1525, TS 11-1486-1642, TS 12-1501-1582, TS 11-1480-1633, TS 96 -1207-169, TS 11-1467-1633, TS 09-1442-1525. The experience was monofactorial, in which the analyzed factor was the genotype, consisted of 14 variants, divided into 3 repetitions. As a control, the average of the determined values was determined for each parameter taken in the study. The parameters analyzed were: minitubers number / plant and minitubers weight minitubers / pl. TS 12-1489-1574 potato line was the most representative, being a productive line, which was distinguished by a number of 11.83 minitubers / plant and a significantly positive difference of + 4.21 comparative with control taken in the study. Weight of minitubers / plant was influenced by genotype, proving superiority TS11-1468-1633 potato line which had a good capacity to produce minitubers with high weight (295.17 g) (and a distinct significant difference, positive, to control +114,83). Thus, this potato line has a high potential for producing high yields

Behaviour of different potato varieties by simulating in vitro of hydric stress conditions

The water deficit, extreme temperatures and low atmospheric humidity lead to drought, which is one of the limiting factors affecting crop quality and quantity. In vitro selection may shorten considerably the time selection of desirable traits and completes selection in the field. In vitro tissue culture can be used to determine the drought tolerance of the various varieties assuming that there is a correlation between plant cells in vitro and in vivo. For determining the resistance to water stress, the research was conducted in the Laboratory of Vegetal Tissue Culture and experience consisted of two factors: variety and nutritive medium with different osmotic agents. With the increasing amount of sorbitol and PEG, water absorption becomes difficult for plantlets from nutrient medium and thus was simulate the effect of drought over microplants. With the increasing amount of sorbitol or PEG into the growth medium, the drought intensity was bigger. Observations were made for different parameters: the average number of leaves; the average number of internodes; the average height of plantlet (cm); the average root length (cm); the average weight of fresh plantlet (mg); the average fresh root weight (mg). This study was performed in order to determine the best osmotic agent put into the in vitro medium for simulate the water stress, as well as for for testing the particular genotypes genotypes on different culture media causing selection pressure of water stress

CHALLENGES AND SOLUTIONS WITHIN IN VITRO PROPAGATION OF SWEET POTATO (IPOMOEA BATATAS L.)

The purpose of this study was to find viable solutions for problems encountered during in vitro cultivation of sweet potato (Ipomoea batatas (L.) Lam.). Plant tissue culture are especially suitable for obtaining and maintaining a stock of pathogen-free plants, which can then be multiplied and used as an initial material. Although tissue cultures, carried out under controlled conditions, in a sterile environment, have important applications in plant biotechnologies, however, there are many factors that can influence their success. In addition to the minimum equipment of a plant tissue culture laboratory good function (adequate spaces, equipment, chemicals, laboratory glassware and tools etc.) and trained workers, the success of such an activity also depends on finding the best conditions for the harmonious growth and development of plant organisms, in a controlled environment. These challenges relate in particular to: introducing in vitro conditions of biological material from the in vivo environment; sterilization of the material which will be used as a source of explants; choosing a suitable growth medium, microbial contamination control; establishing optimal parameters in terms of temperature and photoperiod etc. The factors mentioned above vary by species and, more than that, by variety. In this study, the research was carried out over four years, on five Korean sweet potato varieties, at the Research Laboratory for Plant Tissue Cultures of the National Research and Development Institute for Potato and Sugar Beet, Brasov

The Growth Response of Several Potato Genotypes (<i>Solanum tuberosum</i> L.) to Induced Water Stress Using Sorbitol and Polyethylene Glycol

The current paper aimed to study the in vitro response of potato genotypes to water stress induced by adding sorbitol and polyethylene glycol in the culture medium. The biological material analysed in the experiment was represented by a Romanian line ‘LP 11-1525/1’ and two isogenic lines ‘LI 101’ and ‘LI 102’. For cultures initiation, the line ‘LP 11-1525/1’ was started from meristems and for the other two genotypes true potato seeds were used. The studied potato genotypes behaved differently depending on the analysed parameters and on the treatment applied for drought tolerance. It was noted that the line ‘LP 11-1525/1’ achieved good results for most of the growth parameters studied, and also the lines derived from true potato seeds behaved well, in some cases even exceeding the line derived from meristems. Of the lines derived from true potato seeds, the best performance was noted for line ‘LI 101-6’ in all the analysed parameters, both on sorbitol and PEG medium. In addition, lines ‘LI 101-7’ and ‘LI 102-4’ achieved good results on both variants of medium used to mediate water stress. Therefore, establishing drought tolerance individuals within populations derived from true potato seeds using sorbitol and polyethylene glycol might be applied

Preliminary studies regarding the incidence of potato virus y in seed potatoes in Romania (for several cultivars)

The farmers income is affected strongly by potato virus diseases. Potato Virus Y has become in the last years one of the most damaging pathogen of potato crop. It can cause serious reduced yield, stand loss and decrease of the tuber’s quality. The necrotic and recombinant strains PVY play an important rol in the spreading of this virus. Elimination of this pathogen from potato supply is essential for seed production and the choice of resistant varieties to the infection with this virus could be one of the measures recommended for farmers and producers. The results of this preliminary study show that varieties resistant to necrotic strains PVY in our study (samples taken from theregionsBraşov, Covasna, Harghita, Cluj, Suceava, in 2014) were the following: Riviera, Bellarosa, Jelly, Roclas, Christian

Spatial Distribution and Molecular Diversity of Archaeal Communities in the Extreme Hypersaline Meromictic Brâncoveanu Lake (Transylvanian Basin, Romania)

<p>Dating from the Middle Miocene, the massive halite deposits lying beneath the Transylvanian Basin (Central Romania) have been valuable mineral resources quarried for millennia. Among the numerous hypersaline pit lakes that resulted from this mining, Brâncoveanu Lake is unique by its extreme salinity. Assessment of physicochemical variables, water chemistry and trophic status indicated that Brâncoveanu Lake is a permanently stratified, pH-neutral, NaCl-rich and eutrophied system. We investigated the abundance, molecular diversity and vertical distribution of archaeal community by culture-independent approaches. Additionally, the most relevant environmental parameters shaping the archaeal community composition were evaluated by statistical methods. Archaea appeared to largely outnumber Bacteria; altogether the great prevalence of Halobacteriaceae-related sequences could imply a major contribution of this group to the biogeochemical carbon turnover. The fairly distinct composition of archaeal communities reflects the lake's physicochemical stratification. Among the limnological factors, salinity and oxygen showed a significant impact on determining the composition and structure of archaeal assemblages. Furthermore, Brâncoveanu Lake might harbor novel microorganisms such as members of the recently described phylum Nanohaloarchaea. Overall, this study reported the occurrence of halophilic Archaea in a little explored hydrogeochemical system and provided a better insight into geomicrobiology of meromictic hypersaline pit lakes.</p