Promoter and coding sequence diversity of CsCCD1 may contribute to the differential accumulation of floralβ-ionone in fresh tea leaves

The carotenoid-derived volatileβ-ionone makes an important contribution to tea fragrance.Here,we qualitatively and quantitatively analysed 15 carotenoids in tea leaves of 13 cultivars by UHPLC-APCI-MS/MS.The 13 cultivars were divided into two groups by PCA(Principal Component Analysis)clustering analysis of their carotenoid content,and OPLS-DA(Orthogonal projections to latent structures)indicated that the levels ofβ-carotene(VIP=2.89)and lutein(VIP=2.30)were responsible for much of the variation between the two groups.Interestingly,theβ-carotene toβ-ionone conversion rates in Group 1 were higher than in Group 2,while theβ-carotene content was significantly lower in Group 1 than in Group 2.Theβ-ionone content was significantly higher in Group 1.Pearson Correlation Coefficient calculation between the transcription level of candidate genes(CsCCD1 and CsCCD4)and the accumulation ofβ-ionone indicated that CsCCD1 may involve in the formation ofβ-ionone in 13 cultivars.Prokaryotic expression and in vitro enzyme activity assays showed that‘Chuanhuang 1’had an amino acid mutation in carotenoid cleavage dioxygenases 1(CsCCD1)compared with‘Shuchazao’,resulting in a significantly higherβ-ionone content in‘Chuanhuang 1’.Sequence analysis showed that‘Chuanhuang 1’and‘Huangdan’had different CsCCD1 promoter sequences,leading to significantly higher CsCCD1 expression andβ-ionone accumulation in‘Chuanhuang 1’.These results indicated that the promoter and coding sequence diversity of CsCCD1 might contribute to the differential accumulation ofβ-ionone in different tea cultivars.

A geraniol synthase regulates plant defense via alternative splicing in tea plants

Geraniol is an important contributor to the pleasant floral scent of tea products and one of the most abundant aroma compounds in tea plants;however,its biosynthesis and physiological function in response to stress in tea plants remain unclear.The proteins encoded by the full-length terpene synthase(CsTPS1)and its alternative splicing isoform(CsTPS1-AS)could catalyze the formation of geraniol when GPP was used as a substrate in vitro,whereas the expression of CsTPS1-AS was only significantly induced by Colletotrichum gloeosporioides and Neopestalotiopsis sp.infection.Silencing of CsTPS1 and CsTPS1-AS resulted in a significant decrease of geraniol content in tea plants.The geraniol content and disease resistance of tea plants were compared when CsTPS1 and CsTPS1-AS were silenced.Down-regulation of the expression of CsTPS1-AS reduced the accumulation of geraniol,and the silenced tea plants exhibited greater susceptibility to pathogen infection than control plants.However,there was no significant difference observed in the geraniol content and pathogen resistance between CsTPS1-silenced plants and control plants in the tea plants infected with two pathogens.Further analysis showed that silencing of CsTPS1-AS led to a decrease in the expression of the defense-related genes PR1 and PR2 and SA pathway-related genes in tea plants,which increased the susceptibility of tea plants to pathogens infections.Both in vitro and in vivo results indicated that CsTPS1 is involved in the regulation of geraniol formation and plant defense via alternative splicing in tea plants.The results of this study provide new insights into geraniol biosynthesis and highlight the role of monoterpene synthases in modulating plant disease resistance via alternative splicing.

QTL analysis for ascorbic acid content in strawberry fruit reveals a complex genetic architecture and association with GDP-L-galactose phosphorylase

Strawberry(Fragaria×ananassa)fruits are an excellent source of L-ascorbic acid(AsA),a powerful antioxidant for plants and humans.Identifying the genetic components underlying AsA accumulation is crucial for enhancing strawberry nutritional quality.Here,we unravel the genetic architecture of AsA accumulation using an F1 population derived from parental lines‘Candonga’and‘Senga Sengana’,adapted to distinct Southern and Northern European areas.To account for environmental effects,the F1 and parental lines were grown and phenotyped in five locations across Europe(France,Germany,Italy,Poland and Spain).Fruit AsA content displayed normal distribution typical of quantitative traits and ranged five-fold,with significant differences among genotypes and environments.AsA content in each country and the average in all of them was used in combination with 6,974 markers for quantitative trait locus(QTL)analysis.Environmentally stable QTLs for AsA content were detected in linkage group(LG)3A,LG 5A,LG 5B,LG 6B and LG 7C.Candidate genes were identified within stable QTL intervals and expression analysis in lines with contrasting AsA content suggested that GDP-L-Galactose Phosphorylase FaGGP(3A),and the chloroplast-located AsA transporter gene FaPHT4;4(7C)might be the underlying genetic factors for QTLs on LG 3A and 7C,respectively.We show that recessive alleles of FaGGP(3A)inherited from both parental lines increase fruit AsA content.Furthermore,expression of FaGGP(3A)was two-fold higher in lines with high AsA.Markers here identified represent a useful resource for efficient selection of new strawberry cultivars with increased AsA content.

Volatile compound-mediated plant-plant interactions under stress with the tea plant as a model

Plants respond to environmental stimuli via the release of volatile organic compounds(VOCs),and neighboring plants constantly monitor and respond to these VOCs with great sensitivity and discrimination.This sensing can trigger increased plant fitness and reduce future plant damage through the priming of their own defenses.The defense mechanism in neighboring plants can either be induced by activation of the regulatory or transcriptional machinery,or it can be delayed by the absorption and storage of VOCs for the generation of an appropriate response later.Despite much research,many key questions remain on the role of VOCs in interplant communication and plant fitness.Here we review recent research on the VOCs induced by biotic(i.e.insects and pathogens)and abiotic(i.e.cold,drought,and salt)stresses,and elucidate the biosynthesis of stress-induced VOCs in tea plants.Our focus is on the role of stress-induced VOCs in complex ecological environments.Particularly,the roles of VOCs under abiotic stress are highlighted.Finally,we discuss pertinent questions and future research directions for advancing our understanding of plant interactions via VOCs.

UGT74AF3 enzymes specifically catalyze the glucosylation of 4-hydroxy-2,5-dimethylfuran-3(2H)-one,an important volatile compound in Camellia sinensis

4-Hydroxy-2,5-dimethylfuran-3(2H)-one(HDMF)is an important odorant in some fruits,and is proposed to play a crucial role in the caramel-like notes of some teas.However,its biosynthesis and metabolism in tea plants are still unknown.Here,HDMF glucoside was unambiguously identified as a native metabolite in tea plants.A novel glucosyltransferase UGT74AF3a and its allelic protein UGT74AF3b specifically catalyzed the glucosylation of HDMF and the commercially important structural homologues 2(or 5)-ethyl-4-hydroxy-5(or 2)-methylfuran-3(2H)-one(EHMF)and 4-hydroxy-5-methylfuran-3(2H)-one(HMF)to their correspondingβ-D-glucosides.Site-directed mutagenesis of UGT74AF3b to introduce a single A456V mutation resulted in improved HDMF and EHMF glucosylation activity and affected the sugar donor preference compared with that of the wild-type control enzyme.The accumulation of HDMF glucoside was consistent with the transcript levels of UGT74AF3 in different tea cultivars.In addition,transient UGT74AF3a overexpression in tobacco significantly increased the HDMF glucoside contents,and downregulation of UGT74AF3 transcripts in tea leaves significantly reduced the concentration of HDMF glucoside compared with the levels in the controls.The identification of HDMF glucoside in the tea plant and the discovery of a novel-specific UDP-glucose:HDMF glucosyltransferase in tea plants provide the foundation for improvement of tea flavor and the biotechnological production of HDMF glucoside.

A dual positional specific lipoxygenase functions in the generation of flavor compounds during climacteric ripening of apple

Lipoxygenase(LOX)is an important contributor to the formation of aroma-active C6 aldehydes in apple(Malus×domestica)fruit upon tissue disruption but little is known about its role in autonomously produced aroma volatiles from intact tissue.We explored the expression of 22 putative LOX genes in apple throughout ripening,but only six LOXs were expressed in a ripening-dependent manner.Recombinant LOX1:Md:1a,LOX1:Md:1c,LOX2:Md:2a and LOX2:Md:2b proteins showed 13/9-LOX,9-LOX,13/9-LOX and 13-LOX activity with linoleic acid,respectively.While products of LOX1:Md:1c and LOX2:Md:2b were S-configured,LOX1:Md:1a and LOX2:Md:2a formed 13(R)-hydroperoxides as major products.Site-directed mutagenesis of Gly567 to an alanine converted the dual positional specific LOX1:Md:1a to an enzyme with a high specificity for 9(S)-hydroperoxide formation.The high expression level of the corresponding MdLOX1a gene in stored apple fruit,the genetic association with a quantitative trait locus for fruit ester and the remarkable agreement in regio-and stereoselectivity of the LOX1:Md:1a reaction with the overall LOX activity found in mature apple fruits,suggest a major physiological function of LOX1:Md:1a during climacteric ripening of apples.While LOX1:Md:1c,LOX2:Md:2a and LOX2:Md:2b may contribute to aldehyde production in immature fruit upon cell disruption our results furnish additional evidence that LOX1:Md:1a probably regulates the availability of precursors for ester production in intact fruit tissue.

Amplification of early drought responses caused by volatile cues emitted from neighboring tea plants

Plants have developed sophisticated mechanisms to survive in dynamic environments.Plants can communicate via volatile organic compounds(VOCs)to warn neighboring plants of threats.In most cases,VOCs act as positive regulators of plant defense.However,the communication and role of volatiles in response to drought stress are poorly understood.Here,we showed that tea plants release numerous VOCs.Among them,methyl salicylate(MeSA),benzyl alcohol,and phenethyl alcohol markedly increased under drought stress.Interestingly,further experiments revealed that drought-induced MeSA lowered the abscisic acid(ABA)content in neighboring plants by reducing 9-cis-epoxycarotenoid dioxygenase(NCED)gene expression,resulting in inhibition of stomatal closure and ultimately decreasing early drought tolerance in neighboring plants.Exogenous application of ABA reduced the wilting of tea plants caused by MeSA exposure.Exposure of Nicotiana benthamiana to MeSA also led to severe wilting,indicating that the ability of drought-induced MeSA to reduce early drought tolerance in neighboring plants may be conserved in other plant species.Taken together,these results provide evidence that drought-induced volatiles can reduce early drought tolerance in neighboring plants and lay a novel theoretical foundation for optimizing plant density and spacing.

Correction: Amplification of early drought responses caused by volatile cues emitted from neighboring tea plants

After the publication of this article 1,the authors became aware that the word of“tea”was not mentioned in the title.To make the title clear and complete,the word‘tea’is added to the title.

Down-regulation of Fra a 1.02 in strawberry fruits causes transcriptomic and metabolic changes compatible with an altered defense response

The strawberry Fra a 1 proteins belong to the class 10 Pathogenesis-Related(PR-10)superfamily.In strawberry,a large number of members have been identified,but only a limited number is expressed in the fruits.In this organ,Fra a 1.01 and Fra a 1.02 are the most abundant Fra proteins in the green and red fruits,respectively,however,their function remains unknown.To know the function of Fra a 1.02 we have generated transgenic lines that silence this gene,and performed metabolomics,RNA-Seq,and hormonal assays.Previous studies associated Fra a 1.02 to strawberry fruit color,but the analysis of anthocyanins in the ripe fruits showed no diminution in their content in the silenced lines.Gene ontology(GO)analysis of the genes differentially expressed indicated that oxidation/reduction was the most represented biological process.Redox state was not apparently altered since no changes were found in ascorbic acid and glutathione(GSH)reduced/oxidized ratio,but GSH content was reduced in the silenced fruits.In addition,a number of glutathione-S-transferases(GST)were down-regulated as result of Fra a 1.02-silencing.Another highly represented GO category was transport which included a number of ABC and MATE transporters.Among the regulatory genes differentially expressed WRKY33.1 and WRKY33.2 were down-regulated,which had previously been assigned a role in strawberry plant defense.A reduced expression of the VQ23 gene and a diminished content of the hormones JA,SA,and IAA were also found.These data might indicate that Fra a 1.02 participates in the defense against pathogens in the ripe strawberry fruits.

The Strawberry Fruit Fra a Allergen Functions in Flavonoid Biosynthesis

1 变应原是的草莓兄弟主要桦树花粉变应原的一个相当或相同的事物赌了 v 1。当变异的遗传型的白水果，被知道被过敏症影响的个人容忍，缺乏它时，它被 Fragaria x ananassa 的红成熟水果综合。Proteomic 分析显示出 1 是的那个兄弟在与 anthocyanin 颜料小径的酶一起的容忍的白水果的遗传型下面调整。在这研究，我们报导三个兄弟的空间、时间的表示一编码不同 isoforms 的基因，和兄弟的短暂调停 RNAi 的 silencing 一在有 ihpRNA 的红水果的栽培变种 Elsanta 的草莓水果的基因构造。作为兄弟的减少的层次的后果 mRNAs，水果被获得那生产了 anthocyanins 和在上游的代谢物的显著地减少的层次。这效果与本氨基丙酸氨 lyase (FaPAL ) 的平行下面规定一致，到 chalcone synthase (FaCHS ) 的更小的程度，抄本层次也在这些水果发现。在 F 的自然地发生的白水果的遗传型。chiloensis 和 F。vesca，一个抄本铺平的兄弟比红水果的变化的那些高，可能在这些变异的遗传型补偿 FaPAL 和 FaCHS 的低表示层次。结果表明那个兄弟表情直接被连接到 flavonoid 生合成和表演变应原有的兄弟在在草莓的颜料形成的必要生物功能水果。

Induction of priming by cold stress via inducible volatile cues in neighboring tea plants^FA

Plants have evolved sophisticated defense mechanisms to overcome their sessile nature.However,if and how volatiles from cold‐stressed plants can trigger interplant communication is still unknown.Here,we provide the first evidence for interplant communication via inducible volatiles in cold stress.The volatiles,including nerolidol,geraniol,linalool,and methyl salicylate,emitted from cold‐stressed tea plants play key role(s)in priming cold tolerance of their neighbors via a C‐repeatbinding factors‐dependent pathway.The knowledge will help us to understand how plants respond to volatile cues in cold stress and agricultural ecosystems.