The patterns of anthocyanin and ABA accumulation and ethylene production as well as the changes in expression of the key genes associated with their synthesis or regulation during berry development were studied using Kyoho grapes(Vitis vinifera × V labrusca'Kyoho').Analysis of gene expression,promoter response and relative mRNA abundance showed that exogenous ABA treatment upregulated the expression level of VlMybA1 and VlMybA2,in which VlMybA1 was significantly expressed and promoted berry skin pigmentation;In contrast,exogenous ACC treatment increased the VlMybA2 expression and anthocyanin accumulation.The interaction between ABA and ethylene was found,100 μmol·L-1 ABA largely induced the production of endogenous ethylene,and 500 μmol·L-1 ACC significantly increased ABA content.Additionally,exogenous ABA treatment increased the relative mRNA abundance of VlMybA2 via ethylene.Collectively,ABA promoted berry skin pigmentation by upregulating the VlMybA1 expression directly and the VlMybA2 expression indirectly via ethylene.
In this study,a total of 296 pear germplasms from National Horticulture Germplasm Resources Center Pear Branch Center(Zhengzhou)were collected for fruit spots observation,data collection and photography.During fruit harvesting period,the indicated pear germplasms were sampled and different fruit spot traits,including fruit spots size,fruit spots density,fruit spots height,and the fruit spots area in unit area were comprehensively analyzed.Additionally,sensory evaluation of fruit appearance quality associated with fruit spots in different pear germplasms was performed,and the apperance quality of different pear germplasms was evaluated by grey relation analysis(GRA)and cluster analysis(CA)to establish a comprehensive evaluation model for pear fruit spot traits.The results showed that the relative correlation degree of fruit spots of 296 pear resources ranged from 0.3158 to 0.6526,and the 296 resources were classified into five grades:excellent,good,medium,poor,and extremely poor.Pear varieties including'Autumn Red''Silk Red''Red Sensatian''Zhongli Meicui''Barlett'and'Dabali'were screened out with excellent fruit spot traits,which have good appearance quality and were consistent with the actual production fruit exterior.On the contrary,pear varieties including'Puguali''Xihuamake''Chili'and'Enli'were screened out with extremely poor fruit spot traits,which have poor appearance quality.Furthermore,the fruit spot traits of 296 pear germplasm resources were divided into five grades by cluster analysis,including excellent,good,medium,poor and extremely poor,which accounted for 7.8％,8.8％,37.1％,34.1％and 12.1％of the tested materials,respectively.Above all,the germplasm resources with excellent fruit spot traits will lay the foundation for the improvement of pear appearance quality,and the germplasm resources with poor fruit traits will be helpful for the investigation of the formation and regulation mechanism underlying pear fruit spots.
'Zhentao 3'is a new peach cultivar bred by'Xinbaihua'as female partent and'Chiyohime'as male parent.The pollen of'Zhentao 3'is sterile.The fruit is round.The average fruit weight is 247.6 g and most fruit skin covered by bright red.The flesh is white,hard and clingstone,and sweet flavor,tolerance to storage and transport.It has 14.1％soluble solids content,0.185％total acid content.The fruit development period is about 96 days.The cultivar has high and consistent yield,up to 25 000-50 000 kg·hm-2.
Pear ring rot disease,caused by the pathogenic agent of Botryosphaeria dothidea.Botryosphaeria dothidea chrysovirus 1(BdCV1)induced to the hypovirulence of B.dothidea LW-C and LW-1,which will be used as an ideal candidate material for biological control of fruit tree ring rot disease.In order to further clarify whether the BdCV1-mediated hypovirulent strain has potential as a good candidate biocontrol resource,LW-C and LW-1 was confrontly cultured with the B.dothidea strains isolated and collected from different geographical origins and Valsa pyri strain XJ-28,which caused serious harm to pear trees,respectively.The obtained derivate strains were detected to be positive for BdCV1,whose growth rates and pathogenicity were further determined and analyzed.The results showed that BdCV1 could be successfully horizontally transmitted to different B.dothidea and V pyri strains with certain frequencies,which further inhibited the growth rates and induced to hypovirulence of the strains.The obtained results revealed BdCV1 could be successfully transmitted to the recipient strains at a certain frequency,which could cause the growth rate to decrease and inhibit the growth of the recipient strains to different extent.The formed lesion extension lengths of derivate strains with BdCV1 range from about two to four times longer than that of the recipient strains,when they are inoculated with pear branches or fruits.It further demonstrated that BdCV1 can inhibit the virulence of recipient strains.In summary,BdCV1 could be horizontally transmitted to different recipient strains,revealing that it has wide host range.It is predicted that BdCV1 could be used as a potential biocontrol factor in pear fungal disease biocontrol in practice.
The effect and potential mechanism of receptor like kinase gene MdLYK1(MD09G1111800)on the resistance to Valsa canker were investigated by bioinformatics analysis,functional verification and expression analysis.The results showed that MdLYK1 was homologous to Arabidopsis receptor kinase gene AtLYK1,with 68.1％amino acid sequence similarity.The transient expression of this gene in'Yanfu 6'fruit significantly improved the fruit Valsa canker resistance.Three overexpressed cell lines were obtained by introducing them into the suspension cells of Pyrus betulifolia Bunge.After inoculation with Valsa pyri,the growth rate of colonies on all overexpressing cell lines was significantly lower than that of wild-type cells.All overexpression cell lines were significantly less sensitive to Valsa pyri metabolites compared to the wild type.In addition,MdLYK1 overexpression significantly enhanced the up-regulated expression of key genes related to signaling such as pathogen-associated molecular patterns triggered immunity,reactive oxygen species,jasmonic acid and other signal-related key genes were up-regulated in the suspension cells of Pyrus betulifolia Bunge.In conclusion,MdLYK1 positively regulates the resistance to apple and pear Valsa canker,and pathogen-associated molecular pattern-triggered immunity,reactive oxygen species and jasmonic acid signals are involved in the regulation of resistance.
