Cold-resistant Cultivars Research Articles

Analysis of the Physiological Parameters of Cold Resistance in Core Winter and Spring Wheat Cultivars

We selected 46 core winter–spring wheat cultivars from China’s main wheat-producing areas as experimental materials to clarify the differences in the physiological parameters of their cold resistance and provide a theoretical basis and high-quality germplasm for cold resistance breeding. We investigated differences in their cold resistance under field conditions for two consecutive years, and determined the physiological parameters of the cold resistance, yield, and quality indicators of different winter–spring wheat cultivars. Our results showed that the cold resistance of winter wheat cultivars was higher than that of spring wheat cultivars. The chlorophyll (Chl), soluble sugar (SS), soluble protein (SP), and free proline (Pro) contents of different winter–spring wheat cultivars were positively correlated with cold resistance, and malondialdehyde (MDA) content was negatively correlated with cold resistance. The five physiological parameters can be used as physiological indicators for the breeding of cold-resistant cultivars. The cold resistance, yield, and quality indicators of different spring and winter wheat cultivars were comprehensively evaluated by using the average membership value and comprehensive score. It was found that the average membership value and comprehensive score of winter wheat cultivars were higher than those of spring wheat cultivars. Through classification using the K-means method, the cold-resistant, high-yield, and high-quality cultivars were screened out, namely, Jimai23 (JM23), Jimai44 (JM44), Shannong57 (SN57), and Jinmai 919 (JM919).

Comparative transcriptomics analysis of tolerant and sensitive genotypes reveals genes involved in the response to cold stress in bitter gourd (Momordica charantia L.)

Bitter gourd is an economically important horticultural crop for its edible and medicinal value. However, the regulatory mechanisms of bitter gourd in response to cold stress are still poorly elucidated. In this study, phytohormone determination and comparative transcriptome analyses in XY (cold-tolerant) and QF (cold-sensitive) after low temperature treatment were conducted. Under cold stress, the endogenous contents of abscisic acid (ABA), jasmonic acid (JA) and salicylic acid (SA) in XY were significantly increased at 24 h after treatment (HAT), indicating that ABA, JA and SA might function in regulating cold resistance. RNA-seq results revealed that more differentially expressed genes were identified at 6 HAT in QF and 24 HAT in XY, respectively. KEGG analysis suggested that the plant hormone signal transduction pathway was significantly enriched in both genotypes at all the time points. In addition, transcription factors showing different expression patterns between XY and QF were identified, including CBF3, ERF2, NAC90, WRKY51 and WRKY70. Weighted gene co-expression network analysis suggested MARK1, ERF17, UGT74E2, GH3.1 and PPR as hub genes. These results will deepen the understanding of molecular mechanism of bitter gourd in response to cold stress and the identified genes may help to facilitate the genetic improvement of cold-resistant cultivars.

Integrated transcriptomic and metabolomic analysis provides insights into cold tolerance in lettuce (Lactuca sativa L.)

The popular leafy vegetable lettuce (Lactuca sativa L.) is susceptible to cold stress during the growing season, which slows growth rate, causes leaf yellowing and necrosis, and reduced yield and quality. In this study, transcriptomic and metabolomic analyses of two cold-resistant lettuce cultivars (GWAS-W42 and F11) and two cold-sensitive lettuce cultivars (S13K079 and S15K058) were performed to identify the mechanisms involved in the cold response of lettuce. Overall, transcriptome analysis identified 605 differentially expressed genes (DEGs), including significant enrichment of genes involved in the flavonoid and flavonol (CHS, CHI, F3H, FLS, CYP75B1, HCT, etc.) biosynthetic pathways related to oxidation–reduction and catalytic activity. Untargeted metabolomic analysis identified fifteen flavonoid metabolites and 28 other metabolites potentially involved in the response to cold stress; genistein, quercitrin, quercetin derivatives, kaempferol derivatives, luteolin derivatives, apigenin and their derivatives accumulate at higher levels in cold-resistant cultivars. Moreover, MYBs, bHLHs, WRKYs and Dofs also play positive role in the low temperature response, which affected the expression of structural genes contributing to the variation of metabolites between the resistant and sensitive. These results provide valuable evidence that the metabolites and genes involved in the flavonoid biosynthetic pathway play important roles in the response of lettuce to cold stress.

MicroRNA Profiling Revealed the Mechanism of Enhanced Cold Resistance by Grafting in Melon (Cucumis melo L.).

Grafting is widely used to improve the resistance to abiotic stresses in cucurbit plants, but the effect and molecular mechanism of grafting on cold stress are still unknown in melon. In this study, phenotypic characteristics, physiological indexes, small-RNA sequencing and expression analyses were performed on grafted plants with pumpkin rootstock (PG) and self-grafted plants (SG) to explore the mechanism of changed cold tolerance by grafting in melon. Compared with SG plants, the cold tolerance was obviously enhanced, the malondialdehyde (MDA) content was significantly decreased and the activities of antioxidant enzymes (superoxide dismutase, SOD; catalase, CAT; peroxidase, POD) were significantly increased in PG plants. Depend on differentially expressed miRNA (DEM) identification and expression pattern analyses, cme-miR156b, cme-miR156f and chr07_30026 were thought to play a key role in enhancing low-temperature resistance resulting from grafting. Subsequently, 24, 37 and 17 target genes of cme-miR156b, cme-miR156f and chr07_30026 were respectively predicted, and 21 target genes were co-regulated by cme-miR156b and cme-miR156f. Among these 57 unique target genes, the putative promoter of 13 target genes contained the low-temperature responsive (LTR) cis-acting element. The results of qRT-PCR indicated that six target genes (MELO3C002370, MELO3C009217, MELO3C018972, MELO3C016713, MELO3C012858 and MELO3C000732) displayed the opposite expression pattern to their corresponding miRNAs. Furthermore, MELO3C002370, MELO3C016713 and MELO3C012858 were significantly downregulated in cold-resistant cultivars and upregulated in cold-sensitive varieties after cold stimulus, and they acted as the key negative regulators of low-temperature response in melon. This study revealed three key miRNAs and three putative target genes involved in the cold tolerance of melon and provided a molecular basis underlying how grafting improved the low-temperature resistance of melon plants.

Genome-wide identification and expression analysis of the calmodulin-binding transcription activator (CAMTA) family genes in tea plant

BackgroundAs a type of calmodulin binding protein, CAMTAs are widely involved in vegetative and reproductive processes as well as various hormonal and stress responses in plants. To study the functions of CAMTA genes in tea plants, we investigated bioinformatics analysis and performed qRT-PCR analysis of the CAMTA gene family by using the genomes of ‘ShuChaZao’ tea plant cultivar.ResultsIn this study, 6 CsCAMTAs were identified from tea plant genome. Bioinformatics analysis results showed that all CsCAMTAs contained six highly conserved functional domains. Tissue-specific analysis results found that CsCAMTAs played great roles in mediating tea plant aging and flowering periods. Under hormone and abiotic stress conditions, most CsCAMTAs were upregulated at different time points under different treatment conditions. In addition, the expression levels of CsCAMTA1/3/4/6 were higher in cold-resistant cultivar ‘LongJing43’ than in the cold-susceptible cultivar ‘DaMianBai’ at cold acclimation stage, while CsCAMTA2/5 showed higher expression levels in ‘DaMianBai’ than in ‘LongJing43’ during entire cold acclimation periods.ConclusionsIn brief, the present results revealed that CsCAMTAs played great roles in tea plant growth, development and stress responses, which laid the foundation for deeply exploring their molecular regulation mechanisms.

Comparison of transcriptome and metabolome analysis revealed differences in cold resistant metabolic pathways in different apple cultivars under low temperature stress

Freezing injury in winter is an important abiotic stress that seriously affects plant growth and development. Deciduous fruit trees resist freezing injury by inducing dormancy. However, different cultivars of the same species have different cold resistance strategies. Little is known about the molecular mechanism of apple trees in response to freezing injury during winter dormancy. Therefore, in this study, 1-year-old branches of the cold-resistant cultivar ‘Hanfu’ (HF) and the cold-sensitive cultivar ‘Changfuji No. 2’ (CF) were used to explore their cold resistance through physiological, biochemical, transcriptomics, and metabolomics analyses. Combining physiological and biochemical data, we found that HF had a stronger osmotic regulation ability and antioxidant enzyme activity than CF, as well as stronger cold resistance. The functional enrichment analysis showed that both cultivars were significantly enriched in pathways related to signal transduction, hormone regulation, and sugar metabolism under freezing stress. In addition, the differentially expressed genes (DEGs) encoding galactinol synthase, raffinose synthase, and stachyose synthetase in raffinose family oligosaccharides (RFOs) metabolic pathways were upregulated in HF, and raffinose and stachyose were accumulated, while their contents in CF were lower. HF accumulated 4-aminobutyric acid, spermidine, and ascorbic acid to scavenge reactive oxygen species (ROS). While the contents of oxidized glutathione, vitamin C, glutathione, and spermidine in CF decreased under freezing stress, consequently, the ability to scavenge ROS was low. Furthermore, the transcription factors apetala 2/ethylene responsive factor (AP2/ERF) and WRKY were strongly induced under freezing stress. In summary, the difference in key metabolic components of HF and CF under freezing stress is the major factor affecting their difference in cold resistance. The obtained results deepen our understanding of the cold resistance mechanism in apple trees in response to freezing injury during dormancy.

Comparative metabolomic analysis reveals the involvement of catechins in adaptation mechanism to cold stress in tea plant (Camellia sinensis var. sinensis)

Cold stress is a major environmental factor that affects tea production and quality. In this study, the global profiles of metabolites in response to cold acclimation (CA) of three tea plant cultivars with contrasting cold tolerances were investigated using UPLC/MS and GC/MS analyses. A total of 167 and 68 metabolites, which were CA responsive and showed differential accumulation in the susceptible and resistant cultivars under CA, were found from UPLC/MS and GC/MS analyses, respectively. The analysis revealed that higher levels of primary metabolites (amino acids, ascorbic acid, intermediates of the tricarboxylic acid cycle, and carbohydrates) were present in the resistant cultivar. Flavonoids (kaempferol, quercetin, myricetin, and catechin), which are secondary metabolites, also showed high accumulation in the cold-resistant cultivar. Accordingly, under CA, catechin component content in the four cold-resistant accessions was higher than that in the three cold-susceptible accessions, indicating that catechins play important roles in the cold response. Moreover, exogenous epigallocatechin gallate (EGCG) application conferred tolerance to freezing stress in tea plants. Tea leaves treated with EGCG exhibited decreased levels of relative electrolyte leakage and malondialdehyde content and increased reactive oxygen species scavenging activity and Fv/Fm under freezing conditions. Expression analysis of cold-regulated genes indicated that EGCG facilitated the transcriptional activation of CsICE1 - CsCBF - CsCOR pathway to improve the freezing tolerance of tea plants. Taken together, the induction of stress tolerance-related metabolites was greater in the cold-resistant cultivar than in susceptible cultivars. This study highlights the important roles of catechins, especially EGCG, in cold tolerance. • The induction of stress tolerance-related metabolites was greater in the cold-resistant tea cultivar. • Flavonoids, including catechins, were important for cold tolerance. • Exogenous EGCG application enhanced the freezing tolerance of tea plants. • EGCG activated the CsICE1 - CsCBF - CsCOR pathway to improve the freezing tolerance of tea plant.

Genomic insights into the important ornamental and stress resistance traits of Prunus mume

• Genomic insights into Prunus mume evolution and its important ornamental and stress resistance traits. • Prunus mume had completed genomic projects formation mechanism of flower aroma, flower color, flower type, plant architecture, cold resistance and other traits . Prunus mume is a traditional Chinese ornamental and fruit tree crop with a long history of cultivation and wide use in gardens. With the rapid development of biotechnology, the researchers have successively completed the whole genome sequencing and resequencing of P. mume . They have analyzed the formation mechanism of flower aroma, flower color, flower type, plant architecture, cold resistance and other traits, which lay a theoretical foundation for improving the efficiency of breeding and the molecular breeding designs. In this review paper, we briefly summarized the important research progress of P. mume genomics and molecular biology in recent 10 years, mainly including germplasm resource classification, genomic projects, genetic map, important ornamental traits and stress resistance, cultivation and promotion demonstration of new cold resistant cultivars. Furthermore, the key objectives and directions of future research from this study will contribute to accelerating breeding programs for Prunus species.

The Impact of Cold Acclimatization on Antioxidant Enzyme Activity of Vicia sativa L.

Vicia sativa L. is one of most significant forages all over the world, but yield is decreased by cold stress. This study aimed to investigate the cold stress mechanism of V. sativaunder tissue culture in response to some biochemical analysis. In this study, six V. sativacultivars (Tarım Beyazı, Ankara Moru, 24 Çilli,Kansur and Aygün) were carried out to determine cold resistance in vitroconditions. Doğu Beyazı cultivar was used as a cold resistant plant. For the cold acclimation, two weeks old seedlings were incubated in the test chamber set at 4°C for 14 days to induce cold stress. Leaf samples were obtained at 14 days after cold treatment for physiological analysis evaluation. Cold resistant cultivars were chosen using values of thermal degrees. Moreover, antioxidant enzyme activities were determined at cold acclimated and non-acclimated seedlings. Peroxidase enzyme activities gradually increased at cold acclimation compared to those seedlings at non-acclimated.The highest POX activity was found at Ankara Moru seedlings, while the lowest activity was found at Aygün seedlings. SOD and APX activities were detected inversely at cold acclimation compared to those seedlings at non-acclimated. ChlorophyII A, chlorophyII B and carotenoid values were also determined at cold acclimated seedlings. The highest activities and pigment values were detected at Tarım Beyazı seedlings. Whereas, the lowest activities were found at Ankara Moru and Aygün cultivars. Our results displayed that cold acclimation linked to SOD, APX and POX activities and pigment estimation at in vitro conditions.

Genome-wide identification of IQ67 domain (IQD) gene families in Chinese jujube (Ziziphus jujuba Mill.) and expression profiles in response to cold stress

The plant-specific IQ67 DOMAIN (IQD) gene family is a possible targeted interacting protein of calmodulin that plays important roles in calcium signaling transduction and that functions in various biotic and abiotic stresses. However, no systematic analysis of the IQD gene family has been performed in Chinese jujube (Ziziphus jujuba Mill.). In the current study, 20 ZjIQDs were first identified in Chinese jujube and found to be evenly distributed on 12 chromosomes (chr) except chr 9 through a series of bioinformatic analyses. Phylogenetic analysis of 20 ZjIQDs with the IQDs in rice and Arabidopsis showed that all of the IQDs could be classified into four groups and that each group could be divided into two or three other subgroups. In addition, gene structure and motif composition analysis showed that 20 ZjIQDs had similar/respective gene structures in the same group and that the IQ calmodulin binding motif was conserved. Prediction of calmodulin binding sites revealed that all of the ZjIQDs contained at least one calmodulin binding site, which might indicate that they could be targeted by calmodulin. Syntenic analysis indicated that eight ZjIQDs showed syntenic relationships with those in Arabidopsis and four ZjIQDs showed syntenic relationships with those in rice. The expression profiles of ZjIQDs in response to cold, salt and alkaline stresses showed that most ZjIQDs were up- or downregulated, but ZjIQD15 and 16 were significantly upregulated under these stresses. In addition, ZjIQD15 was significantly regulated by oryzalin treatment (a microtubule disruption drug). Moreover, several ZjIQDs were differentially expressed between diploid and autotetraploid ‘Dongzao’ in response to cold stress, which might have important functions in the regulation of the differential cold resistance between diploid and autotetraploid ‘Dongzao’. This systematic analysis of ZjIQDs could provide important information for further functional characterization of key ZjIQDs in response to cold stress with the aim of breeding cold-resistant cultivars, especially improving the cold tolerance of autotetraploid ‘Dongzao’.

Genome-wide identification, characterization, and expression analysis of tea plant autophagy-related genes (CsARGs) demonstrates that they play diverse roles during development and under abiotic stress

BackgroundAutophagy, meaning ‘self-eating’, is required for the degradation and recycling of cytoplasmic constituents under stressful and non-stressful conditions, which helps to maintain cellular homeostasis and delay aging and longevity in eukaryotes. To date, the functions of autophagy have been heavily studied in yeast, mammals and model plants, but few studies have focused on economically important crops, especially tea plants (Camellia sinensis). The roles played by autophagy in coping with various environmental stimuli have not been fully elucidated to date. Therefore, investigating the functions of autophagy-related genes in tea plants may help to elucidate the mechanism governing autophagy in response to stresses in woody plants.ResultsIn this study, we identified 35 C. sinensis autophagy-related genes (CsARGs). Each CsARG is highly conserved with its homologues from other plant species, except for CsATG14. Tissue-specific expression analysis demonstrated that the abundances of CsARGs varied across different tissues, but CsATG8c/i showed a degree of tissue specificity. Under hormone and abiotic stress conditions, most CsARGs were upregulated at different time points during the treatment. In addition, the expression levels of 10 CsARGs were higher in the cold-resistant cultivar ‘Longjing43’ than in the cold-susceptible cultivar ‘Damianbai’ during the CA period; however, the expression of CsATG101 showed the opposite tendency.ConclusionsWe performed a comprehensive bioinformatic and physiological analysis of CsARGs in tea plants, and these results may help to establish a foundation for further research investigating the molecular mechanisms governing autophagy in tea plant growth, development and response to stress. Meanwhile, some CsARGs could serve as putative molecular markers for the breeding of cold-resistant tea plants in future research.

Холодоустойчивый сорт сои северного экотипа Баргузин

Холодоустойчивый сорт сои северного экотипа Баргузин

ABA-dependent bZIP transcription factor, CsbZIP18, from Camellia sinensis negatively regulates freezing tolerance in Arabidopsis.

Overexpression of the tea plant gene CsbZIP18 in Arabidopsis impaired freezing tolerance, and CsbZIP18 is a negative regulator of ABA signaling and cold stress. Basic region/leucine zipper (bZIP) transcription factors play important roles in the abscisic acid (ABA) signaling pathway and abiotic stress response in plants. However, few bZIP transcription factors have been functionally characterized in tea plants (Camellia sinensis). In this study, a bZIP transcription factor, CsbZIP18, was found to be strongly induced by natural cold acclimation, and the expression level of CsbZIP18 was lower in cold-resistant cultivars than in cold-susceptible cultivars. Compared with wild-type (WT) plants, Arabidopsis plants constitutively overexpressing CsbZIP18 exhibited decreased sensitivity to ABA, increased levels of relative electrolyte leakage (REL) and reduced values of maximal quantum efficiency of photosystem II (Fv/Fm) under freezing conditions. The expression of ABA homeostasis- and signal transduction-related genes and abiotic stress-inducible genes, such as RD22, RD26 and RAB18, was suppressed in overexpression lines under freezing conditions. However, there was no significant change in the expression of genes involved in the C-repeat binding factor (CBF)-mediated ABA-independent pathway between WT and CsbZIP18 overexpression plants. These results indicate that CsbZIP18 is a negative regulator of freezing tolerance via an ABA-dependent pathway.

New cold-resistant, seedless grapes developed using embryo rescue and marker-assisted selection

One of the major objectives of table grape breeding is to produce seedless grapes of Vitis vinifera L. Of high importance among these objectives is the development of new cold-resistant seedless grapes for the colder regions of the world. Embryo rescue is an effective tool in breeding seedless grapes. Here, we report on nine cross-combinations between seedless cultivars and cold-resistant seedless cultivars or seeded hybrids. We carried out embryo rescue and molecular marker-assisted selection to create new cold-resistant seedless grape germplasm. We also examined the effects of different parents and the use of exogenous hormones on the success of embryo rescue as well as the optimal sampling time for a new seedless cultivar Qinxiu. The results show that a total of 473 new grape genotypes were obtained by embryo rescue using double-phase MM3 (modified ER) as the medium for embryo development and solid phase WPM as the medium for embryo germination and plantlet formation. We found the seedless cultivars Perlette, Qinhong No.2, Ruby Seedless and Qinhong No.10 were the most suitable female parents for embryo rescue, and the cold-resistant seedless cultivar Jupiter (a V. vinifera × V. labrusca hybrid) as the male parent. This was better than the seeded hybrid 0-1-5 (V. vinifera × V. amurensis). The best embryo development medium was MM3 with 500 mg/L CH, 1 mmol/L serine, 0.5 mg/L GA3, 1.0 mg/L IAA and 0.5 mg/L 6-BA. The best embryo germination and plantlet formation medium was WPM with 0.2 mg/L 6-BA and 0.1 mg/L IAA. The best sampling time for Qinxiu for embryo rescue was 42 days after flowering. We obtained a total of 440 hybrids by embryo rescue using the seedless molecular marker SCF27-2000. Hybridization between grape seedless cultivars and cold-resistant cultivars and embryo rescue were performed. We obtained 473 new germplasms and performed marker assisted-selection using SCF27-2000. The embryo rescue system was optimized.

Среднеранний холодоустойчивый сорт сои Иней

Среднеранний холодоустойчивый сорт сои Иней

Среднеранний холодоустойчивый сорт сои Иней

Среднеранний холодоустойчивый сорт сои Иней

Transcriptional and physiological analyses reveal the association of ROS metabolism with cold tolerance in tea plant

Tea plants are sensitive to cold stress and exhibit a high degree of genetic variability for cold tolerance. To understand the networks controlling cold tolerance in tea plants, transcriptome analyses were performed for non-acclimated (NA) and cold-acclimated (CA) conditions using one cold-resistant cultivar and two cold-susceptible cultivars. The comparison analysis found that the candidate regulators, including those involved in the oxidative stress response pathway, genes encoding protein kinases such as MPKs and CIPKs and transcription factors such as WRKYs and MYBs, contributed to the different cold tolerances of the three cultivars. The positive regulatory mechanism of OST1-ICE1 and the negative regulatory mechanism of MPK3-ICE1 were increased and decreased in the cold-resistant cultivar under CA, respectively. Compared with the cold-resistant cultivar, the cold-susceptible cultivars exhibited a higher ROS content along with lower SOD activity in the two-year repeated tests and subsequently experienced more severe leaf damage. The expression levels of ROS production and scavenging genes were higher and lower, respectively, in the two cold-susceptible cultivars under CA. Together, our results indicate that OST1 and MPK3 play vital roles in tea plant cold tolerance regulation, and the activation of ROS-scavenging genes is a primary strategy for tea plants to cope with cold stress during the winter season.

Youth tree behavior of olive ( Olea europaea L.) cultivars in Wudu, China: Cold and drought resistance, growth, fruit production, and oil quality

Abstract The wet, hot summers and cold, dry winters in Wudu, China differ from the climate in the Mediterranean olive-growing region. Eight olive (Olea europaea L.) cultivars (‘Arbequina’, ‘Hojiblanca’, ‘Manzanilla de Cacerena’, ‘Cornicabra’, ‘Picual’, ‘Arbosana’, ‘Koroneiki’, and ‘Empeltre’) were grown in Wudu and evaluated for 5 years after planting. We evaluated the behavior of the youth trees, including their cold and drought resistance, tree growth, oil content, fruit characteristics, fruit production, and oil quality. The results showed that ‘Empeltre’, ‘Picual’, and ‘Arbequina’ were the most cold-resistant cultivars, while ‘Arbosana’ was the least cold resistant. ‘Empeltre’, ‘Hojiblanca’, and ‘Koroneiki’ were the most drought-resistant cultivars, while ‘Arbequina’ and ‘Arbosana’ were the least drought resistant. ‘Empeltre’ and ‘Picual’ showed the most vigorous tree growth, and ‘Koroneiki’ and ‘Arbosana’ grew slowest. The oil contents of cultivars before harvest ranged from 33.61% (‘Cornicabra’) to 50.09% (‘Arbosana’). The fruit productivity was highest in ‘Arbosana’ and lowest in ‘Empeltre’. The olive oils of all cultivars were EVOO (extra virgin olive oil) according to the IOC (International Olive Council) standard, but ‘Empeltre’, ‘Hojiblanca’, and ‘Cornicabra’ had higher linolenic acid contents in oil. We concluded that ‘Arbosana’ was the cultivar with the greatest potential for cultivation in Wudu. It had the highest fruit production and oil content even in the smallest trees, its EVOO quality met the IOC standard, and it was suitable for growth in areas with abundant water and without continuous frost below −4 °C. We concluded that olive trees grow faster in Wudu than in Mediterranean regions, but have lower cold resistance and olive fruit production in Wudu. These results show how olive cultivars can flourish in a new environment and provide an important basis to expand the cultivation of these cultivars to other suitable regions in southern China.

Cold resistance of modern soya cultivars while germinating seeds under the conditions of low positive temperatures

The aim and tasksof the study foresaw the estimation of modern soya cultivars from plant breeding institutions of Ukraine on cold resistance during the period of seeds germination and singling out the resistant genotypes to low temperatures at the stage of germination for including them in plant breeding programs as the initial material and creation of adaptive cultivars to cold.Material and methods.The research was carried out during 2014–2016 years in the laboratory of plant immunity to diseases and pests at the Institute of plant growing named after V.Ya.Yuriev of NAAS. The material for the research was represented by 34 soya cultivars from plant breeding institutions of Ukraine. Cold resistance was determined by the quality of germinated seeds underlow positive temperatures (+10 ºC ) and the percent was calculated from the quantity of tested germinated seeds in the optimum conditions for the crop (+24 ºC).Results and discussion.Soya cultivars involved in test were grown in the research rotation of the plant growing Institute named after V.Ya.Yuriev of NAAS. The weather conditions during the period of soya vegetation by years of study were characterized as optimum in 2014 and 2016 years(HTC=1.14 and 1.32) and arid in 2015 year(HTC=0,6).The results of seeds germination of all soya cultivars in laboratory under the temperature of +10 ºC showed differences between cultivars as to their cold resistance. That allowed to divide them into groups. The group of weak cold resistant cultivars (21–40 %) includes 6 plant breeding elaborations – Pyssanka, Farvater, Russa, Vil’shanka, Sharm, Vezha. The group of cultivars with average cold resistance(41–60 %) comprises 14 cultivars (Bajka, Sprytna, Kobza, Victoryna, Rajduga, Perlyna, Vyshyvanka, Denni, Gali, Rapssodia, Khvylya, Diademma, Khutoryanochka, Knyazhna and Romashka). The group of cultivars with cold resistance higher than average(61–80 %) includes 7 cultivars: Estafeta, Mal’vina, Symphonia, Suzirja, Triada, Zolushka, Mel’pomena. The group of high cold resistant cultivars is represented by 6 cultivars: Podyaka, Krassunya, Siverka, Syajvo, Zlata, Fejeriya.Conclusions.According to the resultsof studying 34 cultivars created in the leading plant breeding institutions 3 cultivars were singled out during 3 years (Melpomena, Podyaka, Syajvo). Among them there are one with higher than average cold resistance (Mel’ponela, 76,6 %) and two with high (Podyaka and Syajvo,89,7 and 91,9 accordingly). Cultivars Zlata, Siverka and Fejeriya are characterized by high level of cold resistance and high crop productivity. Zlata cultivar with the level of cold resistance 87,7% gave the crop productivity higher than conventional standard by 116,6%, Siverka – by 117,7%(the level of cold resistance is 82,6%), the crop productivity of cultivar Fejeriya was higher from conventional standard by 104,9% (the level of cold resistance is 82,7%). The represented cultivars with high and average cold resistance are valuable initial material for soya plant breeding for given trait and are suitable for early terms of sowing

Development and validation of SSR markers based on transcriptome sequencing of Casuarina equisetifolia

Based on Casuarina equisetifolia transcriptome data, the present study developed and validated 15 transferable EST-SSR markers across Casuarina and Allocasuarina species. Casuarina species are valued as pioneer trees for coastal shelter forest construction. To accelerate Casuarina breeding for more robust, attractive, and cold-resistant cultivars, it is essential to introduce molecular marker-assisted breeding. Based on Casuarina equisetifolia transcriptome data, 10,291 EST-SSR loci with the types of 2–6 nucleotide repeats were identified from assembled 118,270 unigenes. An average of one EST-SSR was found every 13.54 kb, and the distribution frequency of SSRs was 8.7%. The most common repeat motifs were dinucleotide with AG/CT and trinucleotide with AAG/CTT. A total of 150 SSR markers were randomly selected for validation, among which 15 produced clear, reproducible and polymorphic bands, and thus were employed for genetic relationship analysis among 26 genotypes from four Casuarina and three Allocasuarina species. A total of 42 bands were identified, varying from 2 to 5 bands per locus with an average of 2.8. Polymorphism information content ranged from to 0.2624 to 0.6177 with a mean value of 0.4265, indicating a high level of polymorphism. The UPGMA dendrogram revealed a high genetic variation resided among species within two genera, Allocasuarina and Casuarina. Meanwhile, the 15 highly polymorphic Casuarina SSR markers were also proved to be transferable across Casuarina and Allocasuarina species. These valuable SSR markers can be applied further for population and evolutionary genetic studies in Casuarinaceae, and will be useful in selection and breeding of Casuarina species for improving cold tolerance.