Molecular characterization of Apple necrotic mosaic virus identified in crabapple(Malus spp.) tree of China

Apple necrotic mosaic virus(ApNMV) was identified in crabapple trees with mosaic symptoms from Zaozhuang, Shandong Province, China, by reverse transcription polymerase chain reaction(RT-PCR) analysis. The complete nucleotide sequences of one isolate from crabapple(ApNMV-Hai) and two isolates from apple(ApNMV-Hua and-Qu) were determined. The sizes of genomic RNA1, 2 and 3 of the three isolates differed from those of the previously reported isolate ApNMV-P126 from Japanese apple, especially RNA3. Compared with the nucleotide(nt) sequence of RNA3 in isolate P126, those in the Hai and Qu isolates were 7 and 33 nt shorter, respectively, and that of isolate Hua was 7 nt longer. Alignment analyses showed that these differences in size were mainly due to differences in the lengths of the 5′ untranslated region(UTR) and the UTR region between the ORFs encoding the movement protein and the coat protein. In the phylogenetic trees constructed using the full genomic sequences of RNA1, 2 and 3, the isolate Hai clustered into a group with the isolate Qu in the RNA1 tree, but formed an individual branch in the RNA2 and 3 trees. Three recombination events were identified in the nucleotide sequences of RNA1 and 2 among the isolates ApNMV-Hai,-Hua, and-Qu. This is the first report of the full genome sequence of ApNMV in crabapple.

Aroma Volatile Compound Analysis of SPME Headspace and Extract Samples from Crabapple (Malus sp.) Fruit Using GC-MS

Volatile compounds from the ripened crabapple fruit of six varieties （Red Splendor, Strawberry Parfait, Pink Spire, Radiant, Sparkler, and Flame） were analyzed by the use of the SPME/GC/MS method. The changes in the volatiles between the ripened and upon full maturity fruit states were studied in Red Splendor and Strawberry Parfait. An effort was made to summarize an effective method for searching and identifying new idioplasms containing a particular fruit aroma within Malus. A total of 37 compounds were identified from the sample. The main aroma volatiles of the six varieties of fruit were comprised of 2-hexenal, 3-hexenal, hexanal, 2,4-hexadienal, benzaldehyde, diethyl phtbalate. The main volatile compound of the crabapple fruit was 2-hexenal, but the relative content percentages were different （45.37, 21.98, 33.56, 32.21, 38.60, and 45.88%）. The aroma components accumulated differently as the fruits ripened. The relative content of aldehydes and esters decreased as alcohols increased after the Red Splendor and Strawberry Parfait fruit ripened. For Red Splendor, the main volatile was still 2-hexenal, but the relative content decreased to 42.89%, and the relative content of alcohols increased by 13.86% as aldehydes and esters declined by 12.16 and 7.18%, respectively. For Strawberry Parfait, the main volatile was changed to cyclohexanol, and the relative content increased to 46.43%, while the relative content of alcohols increased by 49.03% as aldehydes and esters declined by 23.74 and 9.34%, respectively.

Analysis of Leaf Volatiles of Crabapple (<i>Malus</i>sp.) Individuals in Different Aphids’ Resistance

The aim of this experiment was to analyze the leaf volatiles of crabapple (Malus sp.) individuals at different aphid’s resistance, to ascertain the particular ingredients which has lure or aversion effects on aphid, and to provide reference for finding out a simple method to control effectively aphids. Volatiles of leaves from twenty-one different crabapple individuals were evaluated with the method of head space-solid phase micro-extraction and gas chromatography-mass spectrometry (HS-SPME-GC-MS). Volatiles profiles of them were then compared. There are one hundred eighty-six kinds of volatiles were detected with varied contents found in different individuals. And all plants contain eight kinds of common components: 3-Hexen-1-ol, acetate, (Z)-, 4-Hexen-1-ol, (Z)-, n-Decanal, n-Tetradecane, .alpha.-Farnesene, Diethyl Phthalate, Oxime-, methoxy-phenyl- and Dibenzofuran-, wherein the relative content of higher have 3-Hexen-1-ol, acetate, (Z)- and 4-Hexen-1-ol, (Z)-. Specific volatile substances in high resistance plants contain 3-Hexenal, (Z)- and 2-Hexenal, (E)-. Leaf volatiles differ in twenty-one crabapple individuals. High resistance plants specific volatile substances contains 3-Hexenal, (Z)-, 2-Hexenal, (E)- and other small molecular volatile substances, and no-resistance plants all have .beta.-Farnesene.

Phenolic Profile, Antioxidant Activity and Anti-proliferative Activity of Crabapple Fruits

To explore the potential of crabapples as functional food, polyphenols in crabapples and ‘Fuji’ apples were extracted, and the phenolic profile,total polyphenols, antioxidant activity and anti-proliferative activity against several human cancer cells were determined. The results indicated that crabapple extracts have more abundant phenols and higher total polyphenols(from 4.46 to 46.63 mg GAE·g-1 DW) compared to ‘Fuji’ apples.Crabapple extracts possessed higher antioxidant activity than apple by DPPH and ABTS analysis. All fruit extracts exhibited inhibitory effects on proliferation in different cancer cells;however, crabapple extracts performed significantly better, with half inhibitory concentration(IC50)values varied from 48.34 μg·m L-1 to 974.81 μg·m L-1 for colon cancer cells SW480, 64.67–1 466.35 μg·m L-1 for stomach cancer cells BGC-803,78.88–910.64 μg·m L-1 for esophageal cancer cells CaEs-17. Besides, the red crabapples had higher antioxidant activity and anti-proliferative activity than yellow fruits. These results showed that crabapples, especially red crabapples, have great potential as a healthy food, as they are rich in phenolic compounds with high antioxidant and anti-proliferative activities to cancer cells.

In vitro Anthocyanin Induction and Metabolite Analysis in Malus spectabilis Leaves Under Low Nitrogen Conditions

Anthocyanins are the most widely produced secondary metabolites in plants,and they play an important role in plant growth and reproduction.The nitrogen source is an important factor affecting anthocyanin production,but the nitrogen concentrations on metabolism and the underlying genetic basis remain unclear.In this study,in vitro anthocyanin induction was conducted on Malus spectabilis.The leaf explants were cultivated in media containing different nitrogen concentrations.The results suggested that when the nitrogen contents decreased in limit,the color of leaf explants turned from green to red,and increased anthocyanin accumulation led to a change in phenotype.Furthermore,the content of other flavonoids,such as dihydroquercetin,epicatechin,and catechin,increased under low nitrogen conditions.The transcription levels of the general flavonoid pathway genes,from phenylalanine ammonia lyase(PAL)to anthocyanidin synthase(ANS),were associated with the concentration of corresponding flavonoid compounds and phenotype changes.In particular,the expression level of ANS increased substantially under a low nitrogen treatment,which was significantly and positively correlated with the anthocyanin levels(R2=0.72,P<0.05).The increased expression patterns of anthocyanin pathway genes were similar to that of the transcription factor MYB10.We further verified MYB10 played an important role in the anthocyanin pathway in leaves of Malus spectabilis.These results suggested that we can improve the desirable ornamental plant phenotypes by controlling nitrogen content.This process may offer clues to further development of new agricultural practices.