Abiotic stress factors, especially low temperatures, drought, and salinity, represent the major constraints limiting agricultural production in temperate climate. Under the conditions of global climate change, the risk of damaging effects of abiotic stresses on crop production increases. Plant stress response represents an active process aimed at an establishment of novel homeostasis under altered environmental conditions. Proteins play a crucial role in plant stress response since they are directly involved in shaping the final phenotype. In the review, results of proteomic studies focused on stress response of major crops grown in temperate climate including cereals: common wheat (Triticum aestivum), durum wheat (Triticum durum), barley (Hordeum vulgare), maize (Zea mays); leguminous plants: alfalfa (Medicago sativa), soybean (Glycine max), common bean (Phaseolus vulgaris), pea (Pisum sativum); oilseed rape (Brassica napus); potato (Solanum tuberosum); tobacco (Nicotiana tabaccum); tomato (Lycopersicon esculentum); and others, to a wide range of abiotic stresses (cold, drought, salinity, heat, imbalances in mineral nutrition and heavy metals) are summarized. The dynamics of changes in various protein functional groups including signaling and regulatory proteins, transcription factors, proteins involved in protein metabolism, amino acid metabolism, metabolism of several stress-related compounds, proteins with chaperone and protective functions as well as structural proteins (cell wall components, cytoskeleton) are briefly overviewed. Attention is paid to the differences found between differentially tolerant genotypes. In addition, proteomic studies aimed at proteomic investigation of multiple stress factors are discussed. In conclusion, contribution of proteomic studies to understanding the complexity of crop response to abiotic stresses as well as possibilities to identify and utilize protein markers in crop breeding processes are discussed.

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Low temperatures represent a crucial environmental factor determining winter survival (WS) of barley and wheat winter-type varieties. In laboratory experiments, low temperatures induce an active plant acclimation response, which is associated with an enhanced accumulation of several stress-inducible proteins including dehydrins. Here, dehydrin accumulations in sampled wheat (WCS120 protein family, or WCS120 and WDHN13 transcripts) and barley (DHN5 protein) varieties grown in two locations for two winters were compared with the variety WS evaluated by a provocation wooden-box test. A high correlation between dehydrin transcripts or protein relative accumulation and variety WS score was found only in samples taken prior vernalization fulfillment, when high tolerant varieties accumulated dehydrins earlier and to higher level than less tolerant varieties, and the plants have not yet been vernalized. After vernalization fulfillment, the correlation was weak, and the apical development indicated that plants reached double ridge (DR) in barley or stayed before DR in wheat. Dehydrin proteins and transcripts can be thus used as reliable markers of wheat or barley variety winter hardiness in the field conditions; however, only at the beginning of winter, when the plants have not yet finished vernalization. In wheat, a higher correlation was obtained for the total amount of dehydrins than for the individual dehydrin proteins.HIGHLIGHTSMore tolerant winter-type wheat and barley plants reveal higher threshold induction temperatures for dehydrin accumulation in comparison to less tolerant varieties. Thus, more tolerant winter cereals have higher dehydrin levels than the less tolerant ones upon the same ambient temperature in November samplings.A significant correlation between dehydrin transcript/protein accumulation and winter survival was found in both winter wheat and winter barley plants in the field conditions, but only prior to vernalization fulfillment.

Šlechtění hybridů květáku na bázi autoinkompatibility a cytoplazmatické samčí sterility ABSTRAKT: Pro hybridní šlechtění květáku byly ověřovány dva systémy autosterility, autoinkompatibilita (AI) a cytoplazmatická samčí sterilita (CMS). Byla prokázána možnost reprodukce AI a CMS linií v izolačních klecích s využitím hmyzích opylovačů. Nejlepších výsledků při reprodukci AI linií odvozených z odrůdy Montano bylo dosaženo pomocí postřiku 3% roztokem NaCl ve večerních hodinách při opylování čmeláky. Průměrná hmotnost semen na jednu sklizenou rostlinu dosáhla 5 g. Násada semen u dvou CMS linií vyšlechtěných z odrůd Brilant a Fortuna dosáhla po opylení fertilními analogy pomocí včel 0,8 a 2,0 g semen na rostlinu. V hybridizačním pokusu na bázi autoinkompatibility bylo dosaženo výnosu semen 1,8 g na AI rostlinu. Při hybridizaci na bázi samčí sterility výnos semen na CMS rostlinu činil 2,3 g. V předběžném polním pokusu se jako nejlepší projevil F1 hybrid AI linie Montano × fertilní linie Fortuna.Klíčová slova: květák; hybridní šlechtění; autoinkompatibilita; CMS; reprodukce linií; produkce hybridních semen Corresponding author:Ing. Vratislav Kučera, CSc., Výzkumný ústav rostlinné výroby, Drnovská 507, 161 06 Praha 6-Ruzyně,

Proteins are directly involved in plant phenotypic response to ever changing environmental conditions. The ability to produce multiple mature functional proteins, i.e., proteoforms, from a single gene sequence represents an efficient tool ensuring the diversification of protein biological functions underlying the diversity of plant phenotypic responses to environmental stresses. Basically, two major kinds of proteoforms can be distinguished: protein isoforms, i.e., alterations at protein sequence level arising from posttranscriptional modifications of a single pre-mRNA by alternative splicing or editing, and protein posttranslational modifications (PTMs), i.e., enzymatically catalyzed or spontaneous modifications of certain amino acid residues resulting in altered biological functions (or loss of biological functions, such as in non-functional proteins that raised as a product of spontaneous protein modification by reactive molecular species, RMS). Modulation of protein final sequences resulting in different protein isoforms as well as modulation of chemical properties of key amino acid residues by different PTMs (such as phosphorylation, N- and O-glycosylation, methylation, acylation, S-glutathionylation, ubiquitinylation, sumoylation, and modifications by RMS), thus, represents an efficient means to ensure the flexible modulation of protein biological functions in response to ever changing environmental conditions. The aim of this review is to provide a basic overview of the structural and functional diversity of proteoforms derived from a single gene in the context of plant evolutional adaptations underlying plant responses to the variability of environmental stresses, i.e., adverse cues mobilizing plant adaptive mechanisms to diminish their harmful effects.

Effects of microspore culture treatment with antimitotic agents colchicine, trifluralin and oryzalin on the frequency of embryo formation, embryo development, plant regeneration and diploidization rate in three F 1 hybrids of winter rapeseed cultivars were compared. The ploidy level analysis of 1709 flowering microspore-derived plants showed that in vitro applications of all antimitotic drugs increased the rate of doubled haploid (DH) plants significantly. The mean rate of DH plants from the trifluralin treatment was 85.7%, from colchicine 74.1% and 66.5% in the case of oryzalin, while only 42.3% in the untreated control variant whereas in vivo additional application of colchicine at the plantlet stage did not significantly increase the mean rate of DH plants (55.6%). Although there were no significant differences in diploidization efficiency between the in vitro applications of particular antimitotic agents, trifluralin showed to be the most suitable because of its positive effect on embryo development and conversion into whole plants. In addition, the diploidization rate was sufficient and stable in all genotypes tested. The results indicate that the trifluralin treatment of microspore cultures could provide efficient chromosome doubling for the production of doubled haploid lines from winter oilseed rape breeding materials.

Development of doubled haploid lines by means of in vitro microspore culture has been increasingly used for homozygous line production in breeding programmes of Brassica crops due to a possibility of significant time reduction of cultivar development. Whereas this method is routinely used in oilseed rape (Brassica napus), it is still difficult to apply microspore culture techniques to practical breeding of some vegetable brassicas. The main difficulties are the very low embryo yield and insufficient regenerative ability of microspore-derived plants in many of Brassica oleracea genotypes (CARLOS, DIAS 1999;RUDOLF et al. 1999). Very often abnormal embryos occur which need to be subcultured many times to induce normal shoots (KUGINUKI et al. 1999). Direct and rapid plant regeneration is very important for eliminating cytogenetic abnormalities and improving the efficiency of doubled haploid system. Our previous studies (VYVADILOVÁ et al. 1998a(VYVADILOVÁ et al. ,b, 2001 aimed to increase the efficiency of the microspore culture technique, especially by investigating factors affecting pollen embryogenesis and testing the embryogenic responsibility in a broad range of genotypes from Brassica oleracea collection and some breeding materials. The previously optimized microspore culture procedure was used in this study, which was directed at increasing the efficiency of whole plant production. Obtained doubled haploid lines will be evaluated for agronomic and quality traits with an emphasis on fungal disease and virus resistance and promising lines will be used in breeding programmes. MATERIAL AND METHODSBrassica oleracea genotypes including several botanical varieties such as cabbage, cauliflower and kohlrabi used for experiments were selected according to the previous results regarding the embryogenic responsibility. Eight cultivars and landraces of head cabbage (convar. capitata L.) var. alba DC. and var. rubra DC.; four kohlrabi (var. gongylodes L.) open-pollinated cultivars and one self-pollinated line, one commercial F1 hybrid and three experimental hybrids of cauliflower (var. botrytis L.) were used for experiments. After vernalization for 4 months at 4°C in a cold room plants of cabbage and kohlrabi were grown in the growth chamber under controlled environmental conditions with a 16 h photoperiod and day/night temperature 18/12°C. Cauliflower plants were grown in isolation cages in the openair conditions. The microspore culture technique was modified to make it applicable to a wider spectrum of genotypes (VYVADILOVÁ et al. 2001). Green cotyledonary embryos about 5 mm in size were subcultured (for 5 to 7 days) on differentiation medium with benzylaminopurine, indolyl acetic acid and 2% sucrose, solidified by 0.8% agar (Table 1). Afterwards two thirds of both cotyledons were cut off and embryos were transferred onto regeneration medium without phytohormones, with 1% sucrose and 1% agar (Table 2) More than 400 regenerants of R 1 generation were derived in kohlrabi, cabbage and cauliflower by means of different mod...

An improved protocol for Brassica protoplast culture and plant regeneration was developed. Isolated protoplasts from four-weeks-old in vitro shoot tip culture of Brassica oleracea var. botrytis cv. Siria F1 and Brassica napus doubled haploid of breeding line OP-1 were cultured at a density of 9.8-11.2 × 10 4 protoplasts/ml in darkness at 25°C in a modified medium containing 2% glucose, 0.25 mg/l 2,4-D, 1 mg/l BAP and 1 mg/l NAA. The first divisions of protoplasts were observed on the third day of culture in B. oleracea and on the fourth day in B. napus. The protoplast cultures were diluted with low osmotic medium on 7 th and 11 th day. The frequency of dividing cells was about 80% in B. oleracea and 50% in B. napus. After one month, the microcalli of approximately 0.5-1 mm in size were transferred into an induction medium with various combinations of growth regulators. Minimum duration of enzyme treatment time and extended dark period in the initial phase of culture increased the survival rate of protoplasts. Organogenesis started when the calli enlarged in size on an induction medium (1 mg/l NAA, 0.02 mg/l GA 3 , 1 mg/l 2iP) with 2% sucrose and 0.8% agar. Regeneration frequency of calli was found to be 69-75% in B. oleracea and 2-3% in B. napus. Well-developed shoots were transferred for rooting to a half-strength MS medium without growth regulators. More than 100 B. oleracea regenerants were transferred into soil, and they produced normal heads and set seeds. This very simple procedure is efficient and suitable mainly for B. oleracea var. botrytis and represents a background for fusion experiments.