Investigation of the morphological, physiological, biochemical, and catabolic characteristics and gene expression under drought stress in tolerant and sensitive genotypes of wild barley [Hordeum vulgare subsp. spontaneum (K. Koch) Asch. & Graebn.].

BACKGROUND: Barley (H. vulgare L.) is an important cereal crop cultivated across various climates globally. Barley and its ancestor (H. vulgare subsp. spontaneum) are an economically valuable model for genetic research and improvement. Drought, among various abiotic stresses, is a substantial threat to agriculture due to its unpredictable nature and significant impact on crop yield. RESULTS: This study was conducted in both greenhouse and laboratory settings. Prior to the study, wild barley accessions were pre-selected based on their sensitivity or tolerance to drought as determined from fieldwork in the 2020-2021 and 2021-2022 cropping seasons. The effects of three levels of drought stress were evaluated (control, 90-95% field capacity [FC]; mild stress, 50-55% FC; and severe stress, 25-30% FC). Several parameters were assessed, including seedling and root growth, enzymatic activity (CAT, SOD, POD), soluble protein levels, chlorophyll content, carotenoids, abaxial and adaxial stomatal density and dimensions, and relative gene expression of Dhn1, SOD, POD, and CAT. Drought stress significantly increased enzyme activities, especially at 25-30% FC, and more in the tolerant genotype. On the other hand, sensitive genotypes showed a notable increase in stomatal density. Under drought stress, there was a general decline in seedling and root growth, protein content, chlorophyll and carotenoids, and stomatal dimensions. Importantly, gene expression analysis revealed that Dhn1, SOD, POD, and CAT were upregulated under drought, with the highest expression levels observed in the drought-tolerant genotype under severe stress conditions (25-30% FC). CONCLUSIONS: Our investigation highlights the distinct morphological, physiological, biochemical, and gene-expression profiles of drought-resistant and drought-sensitive wild barley genotypes under varying degrees of drought.

Simultaneous responses of photosystem II and soluble proteins of rapeseed to cold acclimation.

This experiment was conducted to assess the quantitative and qualitative changes in soluble proteins as well as some chlorophyll fluorescence parameters in the leaves of a winter canola (Brassica napus L., cv. Licord) under continuous low temperature. Over the experiment, seedlings were initially grown at 15/10 °C (d/n). At fourth fully expanded leafy stage (day 30), a part of the plants were transferred to 4/2°C for 4 weeks. Plants were sampled for protein extraction from leaves in which chlorophyll fluorescence parameters (Fo, Fv, Fm, Fv/Fo, Fm/Fo, Fv/Fm, Fo´, FV´, Fm´ and some other calculated) were also measured. The results showed a clear increase in soluble proteins quantity caused by cold treatment. The enhancements appeared abruptly following the cold exposure to 4°C and lasted. The electrophoretic protein patterns showed changes in the intensity of some polypeptides, besides, induction a new probable protein weighing 47-kW in response to cold treatment. Cold-triggered reduction in maximum quantum yield of PSII (Fv/Fm) was connected especially with drastic decreasing Fv and Fm. Interestingly, high quantitative amounts of soluble proteins along with induction of the new probable polypeptide induced at cold temperature, were attributed to low deduction of maximum quantum yield of PSII. Additionally, more imperative chlorophyll fluorescence parameters changed e.g. qP, NPQ, qL, Y(II) or фPSII etc at light. Nowadays, radar charts or spider plots are the most sophisticated multivariate statistical tools representing physiological responses of plants to abiotic stress conditions or even morphophysiological studies of plants. In rapeseed many researches performed by applying the radar charts for low temperature stresses and interpreted their effects more advancely than common statistical tools. We observed a good representation of the chl fluorescence parameters fluctuations using radar plots. Overall, cold-induced soluble proteins accumulated after longer cold-acclimation, can contribute in photosynthetic apparatus protection against low-temperature damages.

Effect of nitrogen sources on gene expression of Stevia rebaudiana (Bertoni) under in vitro conditions.

Stevia rebaudiana (Bertoni) is a non-caloric sweetener belonging to Asteraceae family. Stevia compounds such as steviol glycosides (SGs) are 200 times sweeter than sugar. Stevioside and rebaudioside A are the two major steviol glycosides. Nitrogen is an essential element for plant growth and development. In this study the effects of nitrogen influenced by different concentrations of NH4NO3 (0, 825 and 1650 mg/l) and KNO3 (0, 950 and 1900 mg/l) is examined in MS medium. To analysis the UGT74G1 and UGT76G1 genes expression, involved in the synthesis of SGs, RT-qPCR technique was performed. Data showed that there were significant differences between all media. The shoot length, seedlings dry weight and leaf fresh weight of stevia increased with applying NH4NO3 along with KNO3. The highest expression of UGT74G1 gene, was observed in plantlets grown on MS medium with 0 mg/l NH4NO3 and 950 mg/l KNO3 (1.291 total lab unit) but the highest expression of UGT76G1 gene, was observed in plantlets grown on MS medium added by 1650 mg/l NH4NO3 +950 mg/l KNO3 (1.08 total lab unit). Moreover, the lowest value of UGT74G1 gene expression were revealed in MS medium added by 1650 mg/l NH4NO3 +0 mg/l KNO3 (0.80 total lab unit) and the lowest values of UGT76G1 gene expression seen in MS medium with 0 mg/l NH4NO3 +950 mg/l KNO3 (0.85 total lab unit) concentrations. The results of this study could be valuable in stevia breeding programs through glycosides biosynthesis pathways.

Evaluating the effect of gamma rays on Zamiifolia (Zamioculcas zamiifolia) plant in vitro and genetic diversity of the resulting genotypes using the ISSR marker.

Zamiifolia (Zamioculcas sp.) is a perennial plant in the Araceae family and one of the new apartment plants in the world. In this study, in order to increase the effectiveness of the breeding program, tissue culture technique and explants of leaf parts were used. The results indicated that 2,4-D (1 mg/l) and BA (2 mg/l) hormones affected positively and significantly callus formation and simultaneous application of NAA and BA (both in 0.5 mg/l) caused the best results regarding seedling production and number, leaves, complete tubers, and root in tissue culture of Zaamifolia. In the study, three cultivars of Zamiifolia (green, black and Dutch) and 12 genotypes resulted from callus formation stage, irradiated with different gamma rays (0 to 175 Gy, with LD50 as 68 Gy) were selected and the presence of genetic diversity was investigated using 22 ISSR primers. Applying ISSR marker showed that the highest amount of PIC values related to the F19(0.47) and F20(0.38) primers, which persuasively isolated the studied genotypes. Moreover, the highest efficiency was detected for AK66 marker based on the MI parameter. The PCA and clustering categorization via UPGMA methodology based on molecular information and Dice index, differentiated the genotypes into 6 groups. Genotypes 1(callus), 2(100 Gy) and 3(cultivar from Holland) created separated groups. The 4th group included 6(callus), 8(0 Gy), 9(75 Gy), 11(90 Gy), 12(100 Gy) and 13(120 Gy) genotypes appearing as the largest group. The 5th group included 7(160 Gy), 10(80 Gy), 14(140 Gy) and 15(Zanziber gem black) genotypes. The last group included 4(mather plant) and 5(callus) genotypes. In this context, genotypes 1, 5, and 6 had probably somaclonal variation. Moreover, genotypes that received doses of 100 and 120 Gy, had a medium diversity. There is a high possibility of introducing a cultivar with a low dose and high genetic diversity in the whole group. Genotype 7 in this classification, received the highest dose of 160 Gy. In this population, the Dutch variety, was used as a new variety. As a result, the ISSR marker could correctly group the genotypes. This is an interesting finding, and it could be hypothesized that the ISSR marker could correctly differentiate Zaamifolia genotypes and probably other ornamental plants under the effect of gamma rays mutagenesis in order to achieve novel variants.