The aim of the study was to assess the role of salicylic acid (SA) and abscisic acid (ABA) in osmotic stress tolerance of wheat seedlings. This was accomplished by determining the impact of the acids applied exogenously on seedlings grown under osmotic stress in hydroponics. The investigation was unique in its comprehensiveness, examining changes under osmotic stress and other conditions, and testing a number of parameters simultaneously. In both drought susceptible (SQ1) and drought resistant (CS) wheat cultivars, significant physiological and biochemical changes were observed upon the addition of SA (0.05 mM) or ABA (0.1 μM) to solutions containing half-strength Hoagland medium and PEG 6000 (−0.75 MPa). The most noticeable result of supplementing SA or ABA to the medium (PEG + SA and PEG + ABA) was a decrease in the length of leaves and roots in both cultivars. While PEG treatment reduced gas exchange parameters, chlorophyll content in CS, and osmotic potential, and conversely, increased lipid peroxidation, soluble carbohydrates in SQ1, proline content in both cultivars and total antioxidants activity in SQ1, PEG + SA or PEG + ABA did not change the values of these parameters. Furthermore, PEG caused a two-fold increase of endogenous ABA content in SQ1 and a four-fold increase in CS. PEG + ABA increased endogenous ABA only in SQ1, whereas PEG + SA caused a greater increase of ABA content in both cultivars compared to PEG. In PEG-treated plants growing until the harvest, a greater decrease of yield components was observed in SQ1 than in CS. PEG + SA, and particularly PEG + ABA, caused a greater increase of these yield parameters in CS compared to SQ1. In conclusion, SA and ABA ameliorate, particularly in the tolerant wheat cultivar, the harmful effects and after effects of osmotic stress induced by PEG in hydroponics through better osmotic adjustment achieved by an increase in proline and carbohydrate content as well as by an increase in antioxidant activity.

Polyamines (PAs) are related to many physiological processes, including soil drought stress. Two yellow lupin ‘Morocco 4’ (drought tolerant) and ‘Taper’ (drought sensitive) were exposed to soil drought for 2 weeks. The half of the examined plants were additionally sprayed with a solution of polyamine biosynthesis inhibitor—dl-α-difluoromethylarginine (DFMA). Yellow lupin leaves showed a 19% increase and seeds a 54% decrease in the total PA contents. The seeds contained fourfold less PAs than the leaves under drought conditions. The highest amount of spermidine and lack of agmatine were found in the leaves, while in the seeds the highest content of spermine and the presence of agmatine was confirmed. The use of DFMA under drought conditions decreased the content of spermine in ‘Morocco 4’ and ‘Taper’ (41 and 19%, respectively) and spermidine in ‘Taper’ (by 13%), as well as reduced two out of three of the yield components. More tolerant ‘Morocco 4’, after DFMA treatment was characterized by a higher spermidine and spermine content and a smaller decrease in yield components compared to the less tolerant ‘Taper’. Simultaneously subjecting plants to soil drought and DFMA treatment caused in ‘Morocco 4’ a decline in the number of pods and seeds per plant and seeds dry weight per plant (64, 50 and 54%, respectively), while in ‘Taper’ a reduction of the number of pods per plant and seeds per pod (32 and 27%, respectively) was observed. These results confirm that PAs are involved in yellow lupin tolerance and may play a protective function under soil drought conditions.

Androgenic responsiveness in anther (AC) and isolated microspore cultures (MC) was analysed using 15 lines of Polish winter rye (Secale cereale L.). The effect of low temperature (LT) alone or in combination with osmotic stress induced by mannitol treatment (MAN) and/or with reduced glutathione (GSH) on the effectiveness of the process was studied. Interestingly, each treatment had a different effect on microspore (mcs) vitality and capability to divide symmetrically. The first criterion for successful embryogenesis was to exceed the threshold number of at least 25% dividing microspores, which determined ‘embryogenic suspension culture’. In some configurations a spectacular effect was achieved, especially in lines highly recalcitrant to androgenesis induction. Relatively high effectiveness of androgenesis induction (up to 4.58 AS per 10⁵ mcs per spike in MC and 21.29 AS per spike in AC) showed that the developed protocol with GSH and/or MAN tiller pre-treatments overcomes the genotypic barrier for androgenesis initiation in rye. Moreover, relatively high, spontaneous genome diploidization (55%) of regenerated plants demonstrated that the described protocols could be effectively integrated into conventional rye breeding programmes.

Enhanced antioxidant defence plays an essential role in plant survival under stress conditions. However, excessive antioxidant activity sometimes suppresses the signal necessary for the initiation of the desired biological reactions. One such example is microspore embryogenesis (ME)—a process of embryo-like structure formation triggered by stress in immature male gametophytes. The study focused on the role of reactive oxygen species and antioxidant defence in triticale (×Triticosecale Wittm.) and barley (Hordeum vulgare L.) microspore reprogramming. ME was induced through various stress treatments of tillers and its effectiveness was analysed in terms of ascorbate and glutathione contents, total activity of low molecular weight antioxidants and activities of glutathione–ascorbate cycle enzymes. The most effective treatment for both species was a combination of low temperature and exogenous application of 0.3 M mannitol, with or without 0.3 mM reduced glutathione. The applied treatments induced genotype-specific defence responses. In triticale, both ascorbate and glutathione were associated with ME induction, though the role of glutathione did not seem to be related to its function as a reducing agent. In barley, effective ME was accompanied by an accumulation of ascorbate and high activity of enzymes regulating its redox status, without direct relation to glutathione content.

Production of doubled haploid (DH) cereals is becoming increasingly important in crop breeding programs, but the methods currently applied still remain inefficient. In this study, we present the procedure for obtaining haploid and DH oat plants by pollination with maize. Thirty-three oat genotypes were used in the experiments. Oat plants (14,543 florets) were pollinated with maize pollen 2 days after emasculation and treated with auxin analogues: 2,4-dichlorophenoxyacetic acid (2,4-D) or 3,6-dichloro-2-methoxybenzoic acid (dicamba), at a concentration of 100 mg dm⁻³. These auxins had no significant influence on the number of haploid embryos developed, but they significantly affected their germination ability, and thus haploid and DH plant production. After application of 2,4-D, 5.06 % of haploid embryos developed per emasculated florets, 1.37 % of haploid plants and 0.54 % of DH lines, whereas after dicamba treatment, 4.3 % of haploid embryos, 0.64 % of haploid plants and 0.25 % of DH lines. Haploid embryos were obtained from all genotypes tested, however, their frequency differed between individual genotypes. The highest number of embryos per emasculated florets (9.0 %) was obtained from the DC09040 genotype after dicamba treatment, and from STH123 × Skorpion (8.9 %) after 2,4-D treatment. The genotype did not significantly affect the development of haploid plants, nevertheless the highest number of DH lines was obtained from the Arab × Typhon genotype. There were 52 DH lines acquired from 28 genotypes, which produced a total of 5227 seeds. The number of seeds varied between the DH lines from 2 to 595. Seeds of all the DH lines produced fertile next generation. DH lines are currently included in breeding programs.

Oat (Avena sativa L.) cultivars ‘Bingo’ and ‘Chwat’ were used to compare the embryogenesis competence of another culture. Despite the embryo-like structures obtained from both tested cultivars, only ‘Chwat’ produced green plantlets, which confirmed the cultivar dependency. ‘Chwat’ produced the highest number of embryo-like structures and green plantlets (0.7/100 anthers and 0.1/100 anthers, respectively). The embryo-like structure formation also depended on cold pretreatment combined with Cu²⁺, Zn²⁺, or Ag⁺ ion supplementation, which was applied during the tiller pretreatment or added to the induction media. The highest number of embryo-like structures (2.1/100 anthers) were observed on anthers derived from the tillers kept in a 50% Hoagland medium with the addition of 10 µM of CuSO₄. In turn, the induction media supplemented with the ions Cu²⁺, Zn²⁺, or Ag⁺ increased neither the number of embryo-like structures nor the green plantlet production compared to the control conditions. However, such ion applications turned out to be most effective when the induction medium was enriched with 25 µM of AgNO₃ and left to obtain the highest number of embryo-like structures and green plantlets (0.8/100 anthers and 0.2/100 anthers, respectively). Therefore, more attention should be paid to the possibilities of adjusting the media nutrient composition, as this may be the only way to significantly increase the efficiency of this method.