Genome-wide identification and function analysis of the sucrose phosphate synthase MdSPS gene family in apple

Sucrose phosphate synthase(SPS)is a rate-limiting enzyme that works in conjunction with sucrose-6-phosphate phosphatase(SPP)for sucrose synthesis,and it plays an essential role in energy provisioning during growth and development in plants as well as improving fruit quality.However,studies on the systematic analysis and evolutionary pattern of the SPS gene family in apple are still lacking.In the present study,a total of seven MdSPS and four MdSPP genes were identified from the Malus domestica genome GDDH13 v1.1.The gene structures and their promoter cis-elements,protein conserved motifs,subcellular localizations,physiological functions and biochemical properties were analyzed.A chromosomal location and gene-duplication analysis demonstrated that whole-genome duplication(WGD)and segmental duplication played vital roles in MdSPS gene family expansion.The Ka/Ks ratio of pairwise MdSPS genes indicated that the members of this family have undergone strong purifying selection during domestication.Furthermore,three SPS gene subfamilies were classified based on phylogenetic relationships,and old gene duplications and significantly divergent evolutionary rates were observed among the SPS gene subfamilies.In addition,a major gene related to sucrose accumulation(MdSPSA2.3)was identified according to the highly consistent trends in the changes of its expression in four apple varieties(‘Golden Delicious’,‘Fuji’,‘Qinguan’and‘Honeycrisp’)and the correlation between gene expression and soluble sugar content during fruit development.Furthermore,the virus-induced silencing of MdSPSA2.3 confirmed its function in sucrose accumulation in apple fruit.The present study lays a theoretical foundation for better clarifying the biological functions of the MdSPS genes during apple fruit development.

Regulation of A 9-cis-epoxycarotenoid Dioxygenase(NCED)Gene from Raspberry on High Salinity and Cold Tolerance

Abscisic acid(ABA)is a plant hormone that plays an important role in plant development and abiotic stress.The 9-cis-epoxycarotenoid dioxygenase(NCED)is a key rate-limiting enzyme in the ABA biosynthetic pathway.The physiological and molecular mechanisms of NCED regulating plant development and abiotic stress tolerance have been reported in many plant species,but gene function of RiNCEDs in Rubus idaeus L.is rarely reported.In this study,the open reading frame(ORF)sequence of RiNCED2 in red raspberry fruit was isolated and the function of this gene under abiotic stress was investigated.While RiNCED2 was induced by cold,high salinity,drought and ABA,it was highly expressed in new leaves as measured by real-time qPCR.Overexpression of RiNCED2 in Arabidopsis under both high-salt and cold stress increased ABA content,demonstrating that RiNCED2 was involved in ABA biosynthesis.Meanwhile,the leaf wilting degree of transgenic Arabidopsis was less,while the content of malondialdehyde(MDA)was significantly reduced,and the chlorophyll content,proline content,peroxidase(POD),catalase(CAT)and superoxide dismutase(SOD)activities were significantly increased.These results indicated that overexpression of RiNCED2 enhanced the resistance of transgenic Arabidopsis to high salt and cold.

Identification of Geographical Origins for Blackcurrant Cultivars Based on Amino Acid Compositions

In this study,a total of 36 blackcurrant(Ribes nigrum L.)cultivars grown in the Northeast of China were selected,including 12 cultivars introduced from Russia,10 from Poland and the rest from local areas.The physicochemical properties and amino acid compositions of these varieties were studied,and the geographical origins of blackcurrants were tracked by multivariate statistical analysis.A total of 23 amino acids were detected in all cultivars,which were rich in glutamine,glutamate,aspartate,asparagine,α-alanine,γ-aminobutyric acid,valine and serine.The content of the total amino acids in these cultivars was from 31.21 mg•100 g-1 to 319.40 mg•100 g-1.Stepwise linear discriminant analysis(SLDA)was introduced to perform satisfactory categorization for blackcurrant cultivars,which achieved a success rate of 88.9%for the identification of geographical origins.These results suggested that the compositions of amino acids in blackcurrants could effectively predict geographical origins.

Genome-wide identification and expression analysis of asparagine synthetase family in apple

Asparagine is an efficient nitrogen transport and storage carrier. Asparagine synthesis occurs by the amination of aspartate which is catalyzed by asparagine synthetase(ASN) in plants. Complete genome-wide analysis and classifications of the ASN gene family have recently been reported in different plants. However, systematic analysis and expression profiles of these genes have not been performed in apple(Malus domestica). Here, a comprehensive bioinformatics approach was applied to identify MdASNs in apple. Then, plant phylogenetic tree, chromosome location, conserved protein motif, gene structure, and expression pattern of MdASNs were analyzed. Five members were identified and distributed on 4 chromosomes with conserved GATase-7 and ASN domains. Expression analysis indicated that all MdASNs mRNA accumulated at the highest level in reproductive organs, namely flowers or fruits, which may be associated with the redistribution of free amino acids in plant metabolic organs and reservoirs. Additionally, most of Md ASNs were dramatically up-regulated under various nitrogen supplies, especially in the aboveground part. Taken together, MdASNs may be assigned to be responsible for the nitrogen metabolism and asparagine synthesis in apple.

Genome-wide analysis of OVATE family proteins in cucumber(Cucumis sativus L.)

OVATE family proteins(OFPs)are plant-specific proteins with a conserved OVATE domain that regulate plant growth and development.Although OFPs have been studied in several species,their biological functions remain largely unknown in cucumber(Cucumis sativus L.).This study identified 19 Cs OFPs distributed on seven chromosomes in cucumber.Most Cs OFP genes were expressed in reproductive organs,but with different expression patterns.Ectopic expression of Cs OFP12-16c in Arabidopsis resulted in shorter and blunt siliques.The overall results indicated that Cs OFP12-16c regulates silique development in Arabidopsis and may have a similar function in cucumber.

Effect of Foliar GA_(3) and ABA Applications on Reactive Oxygen Metabolism in Black Currants (Ribes nigrum L.) During Bud Para-dormancy and Secondary Bud Burst

The secondary bud burst can cause around 10%-20%yield losses in black currants,an economically important crop in parts of Europe,Asia and North America.The metabolism of reactive oxygen species(ROS)has been linked to bud dormancy and its early release(secondary bud burst)in several fruit crops.But the relationship between ROS metabolism and the secondary bud burst is still not well understood in black currants.In the present study,two black currant cultivars(Adelinia and Heifeng)with opposing tendency of exhibiting the secondary bud burst were sprayed with abscisic acid(ABA)and gibberellic acid(GA_(3))to either inhibit or induce the secondary bud burst.The results showed that ABA inhibited the secondary bud burst by reducing the contents of ROS(H_(2)O_(2),O_(2)-·)in buds;decreasing the activities of superoxide dismutase(SOD),peroxidase(POD)and catalase(CAT);and increasing the contents of oxidized glutathione(GSSG)and ascorbic acid(AsA).GA_(3) effectively induced the secondary bud burst by increasing ROS contents;increasing the activities of several antioxidant enzymes,such as SOD,POD,CAT,glutathione reductase(GR),ascorbate peroxidase(APX)and the contents of reduced glutathione(GSH);and decreasing the contents of AsA.The experimental results showed that GA_(3) treatment increased the content of ROS,accelerated the metabolism of reactive oxygen species,and promoted the second burst of black currants.However,ROS metabolism was at a low level under ABA treatment,and the buds remained dormant.These results suggested that ROS metabolism might play an important role in the two black currants of the secondary bud burst.

Physiological Effects of Alkaline Stress on Seedlings of Lonicera caerulea L.

[Objectives]This study was conducted to clarify the saline-alkali tolerance in seedlings of Lonicera caerulea L.[Methods]The L.caerulea seedling variety,Lanjingling,was used as the test material,and alkaline solution(NaHCO 3)with different concentration gradients was used for stress treatment to observe physiological effects on L.caerulea seedlings.[Results]L.caerulea seedlings were most affected by alkaline stress at a treatment concentration of 100 mmol/L,and their osmotic substances(proline,soluble sugar,soluble protein)and antioxidant enzymes(CAT,SOD and POD)were higher in content at a concentration of 100 mmol/L compared with the alkaline stresses in this range.The contents were generally higher,and even in the detection of proline,soluble sugar,SOD and POD,the contents of these substances and enzymes reached a peak at 100 mmol/L.The contents of soluble sugar,CAT,SOD,POD and malondialdehyde were generally higher than that of the control check(CK),and the contents of proline and soluble protein in each treatment concentration were generally higher than that of the CK.[Conclusions]The metabolic physiology of L.caerulea seedlings has a certain adaptability to alkaline stress.