Storage Characteristics of Five Kiwifruit Varieties in Hunan Province

Five kiwifruit varieties(Hongyang, Donghong, Jinyan, Cuiyu, Miliang1)in Hunan were picked and stored at room temperature. Sensory indicators(softening rate, decay rate, and firmness), nutritional quality(soluble solid content, titratable acid, and VC), tissue cell aging indexes(malondialdehyde, membrane permeability),and activity of polyphenol oxidase(PPO) and peroxidase(POD) during storage were analyzed. Results showed that firmness of Hongyang, Miliang1, and Cuiyu decreased rapidly, particularly Hongyang. The firmness of Donghong and Jinyan decreased slowly, but the decrease of Jinyan was slower than that of Donghong. Softening rate and decay rate were significantly different among the varieties. To be specific, the softening rate and decay rate of Jinyan were lower than those of Hongyang. Soluble solid content rose at early stage and then declined. Soluble solid content was high in Hongyang after storage for 12 d and high in Donghong and Jinyan after storage for 15 d. Content of titratable acid dropped slowly. Maximum VC content of Donghong,Jinyan, and Cuiyu was higher than that of Hongyang and Miliang 1. The inflection point of relative conductivity increase increase of Jinyan appeared later than that of Hangyang. The MAD content of Jinyan and Donghong kept at a low level. Storage characteristics of different kiwifruit varieties were significant. Storage time was in the order of Hongyang < Miliang 1 < Cuiyu < Donghong < Jinyan. In summary,Hongyang, Cuiyu, and Miliang1 should not be stored for a long time, while longterm storage is favorable for Jinyan and Donghong.

A chromosome-level genome assembly provides insights into Cornus wilsoniana evolution, oil biosynthesis, and floral bud development

Cornus wilsoniana W.is a woody oil plant with high oil content and strong hypolipidemic effects,making it a valuable species for medicinal,landscaping,and ecological purposes in China.To advance genetic research on this species,we employed PacBio together with Hi-C data to create a draft genome assembly for C.wilsoniana.Based on an 11-chromosome anchored chromosome-level assembly,the estimated genome size was determined to be 843.51 Mb.The N50 contig size and N50 scaffold size were calculated to be 4.49 and 78.00 Mb,respectively.Furthermore,30474 protein-coding genes were annotated.Comparative genomics analysis revealed that C.wilsoniana diverged from its closest species∼12.46 million years ago(Mya).Furthermore,the divergence between Cornaceae and Nyssaceae occurred>62.22 Mya.We also found evidence of whole-genome duplication events and whole-genome triplicationγ,occurring at∼44.90 and 115.86 Mya.We further inferred the origins of chromosomes,which sheds light on the complex evolutionary history of the karyotype of C.wilsoniana.Through transcriptional and metabolic analysis,we identified two FAD2 homologous genes that may play a crucial role in controlling the oleic to linoleic acid ratio.We further investigated the correlation between metabolites and genes and identified 33 MADS-TF homologous genes that may affect f lower morphology in C.wilsoniana.Overall,this study lays the groundwork for future research aimed at identifying the genetic basis of crucial traits in C.wilsoniana.

Citron C-05 inhibits both the penetration and colonization of Xanthomonas citri subsp.citri to achieve resistance to citrus canker disease

Citrus canker,caused by Xanthomonas citri subsp.citri(Xcc),is a serious bacterial disease that affects citrus production worldwide.Citron C-05(Citrus medica)is the only germplasm in the Citrus genus that has been identified to exhibit strong resistance to Xcc.However,it has not been determined when,where,and how Xcc is restricted in the tissues of Citron C-05 during the infection process.In the present study,we investigated the spatiotemporal growth dynamics of an eGFP-labeled virulent Xcc(eGFP-Xcc)strain in Citron C-05 along with five susceptible biotypes(i.e.,lemon,pummelo,sour orange,sweet orange,and ponkan mandarin)upon inoculation via the spraying or leaf infiltration of a bacterial suspension.The results from extensive confocal laser scanning microscopy analyses showed that while Xcc grew rapidly in plants of all five susceptible genotypes,Xcc was severely restricted in the epidermal and mesophyll cell layers of the leaves of Citron C-05 in the early stage of infection.Not surprisingly,resistance against Xcc in Citron C-05 was found to be associated with the production of reactive oxygen species and hypersensitive response-like cell death,as well as greater upregulation of several defense-related genes,including a pathogenesis-related gene(PR1)and a glutathione S-transferase gene(GST1),compared with sweet orange as a susceptible control.Taken together,our results not only provide further valuable details of the spatiotemporal dynamics of the host entry,propagation,and spread of Xcc in both resistant and susceptible citrus plants but also suggest that resistance to Xcc in Citron C-05 may be attributed to the activation of multiple defense mechanisms.

Effects of Different Storage Methods on the Fruit Quality and Physiological Changes in Yihong Honey Peach

Taking Yihong,the main cultivar of mid-ripening honey peaches(Prunus persica)in Hunan,as material,this study explored the effects of different storage methods on the fruit quality and physiological changes in Yihong honey peach by the combination of polyethylene film packaging with low-temperature storage.The results showed that the weight loss rate of packaged storage at normal temperature(T1)was significantly lower than that of unpackaged storage at normal temperature(CK),but there was no significant difference in other indicators.In the middle of storage,the respiration rate and ethylene release of packaged storage at 0℃(T3)were extremely significantly lower or significantly lower than those of unpackaged storage at 0℃(T2),packaged storage at 0℃after cold adapting at 8℃for 5 d(T4),and packaged storage in a fluctuating temperature range of 0~3.5℃(T5).After storage,the structure of the middle lamella in the cell wall of T3 was compact and uniform,and the mitochondrial structure was complete,while the cell walls and mitochondria of T4 and T5 were severely deformed and disintegrated.The activities of antioxidant enzymes peroxidase(POD)and superoxide dismutase(SOD)of T3 was significantly higher than those of T4 and T5,and the content of malondialdehyde(MDA)and polyphenol oxidase(PPO)of T3 was also the lowest.Therefore,0°C packaged storage can effectively delay the senescence of Yihong honey peach and prolong its freshness period.

Transcriptome Sequencing for Sugar and Flavonoid Metabolism in Prunus persica‘Jinxiangyu’

In this study,high performance liquid chromatography(HPLC)and RNA-seq transcriptome sequencing were used to study the changes in soluble sugar components and flavonoids in Prunus persica‘Jinxiangyu’at different developmental stages(20–90 d after flowering)and screen the key genes regulating the formation of soluble sugar and flavonoids in the fruits.The results showed that 60–85 d after flowering was the key stage of quality formation of Prunus persica‘Jinxiangyu’,and the content of soluble sugar,soluble solid,fructose,and sucrose in the fruit increased significantly during this period.The sugar content of ripe fruits was mainly fructose and sucrose.The content of kaempferol glycoside was low in the fruit.Quercetin glycoside content was higher in the young fruit stage and decreased with fruit maturity.There were no anthocyanin compounds in the fruit.The expression levels of genes involved in flavonoid metabolism(ANS,DFR,F3H,FLS,4CL1,etc.)were low in the fruit.A total of 181 differentially expressed genes were identified during fruit development to participate in five sugar metabolism pathways,among which the SDH gene had a higher expression level,which continuously rised in the later stage of fruit development.It mainly promoted the accumulation of fructose content in the later stage of fruit development.The expression levels of SPS1,SS,and SS1 genes were continuously up-regulated,which played a key role in sucrose regulation.The higher expression levels of SUS3 and INVA genes in the early stage of fruit development promoted the degradation of sucrose.