Prediction of Apple Fruit Quality by Soil Nutrient Content and Artificial Neural Network

The effect of soil nutrient content on fruit yield and fruit quality is very important.To explore the effect of soil nutrients on apple quality we investigated 200 fruit samples from 40 orchards in Feng County,Jiangsu Province.Soil mineral elements and fruit quality were measured.The effect of soil nutrient content on fruit quality was analyzed by artificial neural network(ANN)model.The results showed that the prediction accuracy was highest(R2=0.851,0.847,0.885,0.678 and 0.746)in mass per fruit(MPF),hardness(HB),soluble solids concentrations(SSC),titratable acid concentration(TA)and solid-acid ratio(SSC/TA),respectively.The sensitivity analysis of the prediction model showed that soil available P,K,Ca and Mg contents had the greatest impact on the quality of apple fruit.Response surface method(RSM)was performed to determine the optimum range of the available P,K,Ca,and Mg contents in orchards In Feng County,which were 10∼20 mg⋅kg^(−1),170∼200 mg⋅kg^(−1),1000∼1500 mg⋅kg^(−1),and 80∼200 mg⋅kg^(−1),respectively.The research also concluded that improving the content of available P and available Ca in orchard soil was crucial to improve apple fruit quality in Feng County,Jiangsu Province.

Genomic variants of genes associated with three horticultural traits in apple revealed by genome re-sequencing

The apple(Malus×domestica Borkh.)cultivar‘Su Shuai’exhibits greater disease resistance,shorter internodes and lighter fruit flavor compared with its parents‘Golden Delicious’and‘Indo’.To obtain a comprehensive overview of the sequence variation in these three horticultural traits,the genomes of‘Su Shuai’and‘Indo’were resequenced using next-generation sequencing and compared to the genome of‘Golden Delicious’.A wide range of genetic variations were detected,including 2454406 and 18749349 single nucleotide polymorphism(SNP)and 59547 and 50143 structural variants(SVs)in the‘Indo’and‘Su Shuai’genomes,respectively.Among the SVs in‘Su Shuai’,17 genes related to disease resistance,10 genes related to Gibberellin(GA)and 19 genes associated with fruit flavor were identified.The expression patterns of eight of the SV genes were examined using reverse transcription-quantitative polymerase chain reaction(RT-qPCR).The results of this study illustrate the genomic variation in these cultivars and provide evidence for a genetic basis for the horticultural traits of disease resistance,short internodes and lighter flavor exhibited in these cultivars.These results provide a genetic basis for the phenotypic characteristics of‘Su Shuai’and,as such,these SVs could serve as gene-specific molecular markers in maker-assisted breeding of apples.

The R2R3-type MYB transcription factor MdMYB90-like is responsible for the enhanced skin color of an apple bud sport mutant

The anthocyanin content in apple skin determines its red coloration,as seen in a Fuji apple mutant.Comparative RNA-seq analysis was performed to determine differentially expressed genes at different fruit development stages between the wild-type and the skin color mutant.A novel R2R3-MYB transcription factor,MdMYB90-like,was uncovered as the key regulatory gene for enhanced coloration in the mutant.The expression of MdMYB90-like was 21.3 times higher in the mutant.MdMYB90-like regulates anthocyanin biosynthesis directly through the activation of anthocyanin biosynthesis genes and indirectly through the activation of other transcription factors that activate anthocyanin biosynthesis.MdMYB90-like bound to the promoters of both structural genes(MdCHS and MdUFGT)and other transcription factor genes(MdMYB1 and MdbHLH3)in the yeast one-hybrid system,electrophoretic mobility shift assay,and dual-luciferase assay.Transgenic analysis showed that MdMYB90-like was localized in the nucleus,and its overexpression induced the expression of other anthocyanin-related genes,including MdCHS,MdCHI,MdANS,MdUFGT,MdbHLH3,and MdMYB1.The mutant had reduced levels of DNA methylation in two regions(−1183 to−988 and−2018 to−1778)of the MdMYB90-like gene promoter,which might explain the enhanced expression of the gene and the increased anthocyanin content in the mutant apple skin.

Transcriptomic analysis of interstockinduced dwarfism in Sweet Persimmon(Diospyros kaki Thunb.)

Growth monitoring indicated that the height of‘Kanshu’plants with‘Nantong-xiaofangshi’as an interstock was significantly shorter than that of‘Kanshu’plants with no interstock.A transcriptome analysis of the two graft combinations(‘Kanshu’/Diospyros lotus and‘Kanshu’/‘Nantong-xiaofangshi’/Diospyros lotus)was conducted to explore the dwarfing genes related to the use of the‘Nantong-xiaofangshi’interstock.Hormone levels and water conductance were also measured in these two graft combinations.The results indicated that the levels of both IAA and GA were lower in‘Kanshu’that had been grafted onto the‘Nantong-xiaofangshi’interstock than in‘Kanshu’with no interstock;additionally,the water conductance was lower in grafts with interstocks than in grafts without interstocks.The expression of AUX/IAA and auxin-responsive GH3 genes was enhanced in scions grafted on the interstock and was negatively correlated with the IAA content and growth of scions.The expression of GA2ox,DELLA,and SPINDLY genes were also upregulated and associated with a decrease in the level of GA in scions grafted on the interstock.Since one of the GA2ox unigenes was annotated as DkGA2ox1 in Diospyros kaki,but was not functionally validated,a functional analysis was conducted in transgenic tobacco.Overexpression of DkGA2ox1 in transgenic plants resulted in a dwarf phenotype that could be recovered by the exogenous application of GA3.We conclude that the‘Nantong-xiaofangshi’interstock affects the water conductance and expression of genes related to the metabolism and transduction of IAA and GA in the grafted scion and thus regulates phytohormone levels,producing dwarfing.

MdWRKY75e enhances resistance to Alternaria alternata in Malus domestica

The Alternaria alternata apple pathotype adversely affects apple(Malus domestica Borkh.)cultivation.However,the molecular mechanisms underlying enhanced resistance to this pathogen in apple remain poorly understood.We have previously reported that MdWRKY75 expression is upregulated by A.alternata infection in‘Sushuai’apples.In this study,we discovered that overexpression of MdWRKY75e increased the resistance of transgenic apple lines to A.alternata infection,whereas silencing this gene enhanced susceptibility to A.alternata infection.Furthermore,we found that MdWRKY75e directly binds to the MdLAC7 promoter to regulate the biosynthesis of laccase and increase the biosynthesis of lignin during A.alternata infection.Moreover,the thickening of the cell wall enhanced the mechanical defense capabilities of apple.In addition,we found that jasmonic acid remarkably induced MdWRKY75e expression,and its levels in transgenic apple lines were elevated.These results indicate that MdWRKY75e confers resistance to the A.alternata apple pathotype mainly via the jasmonic acid pathway and that pathogenesis-related genes and antioxidant-related enzyme activity are involved in the disease resistance of MdWRKY75e transgenic plants.In conclusion,our fi ndings provide insights into the importance of MdWRKY75e for resistance to A.alternata infection in apples.

Current status and perspective of persimmon research in China

The persimmon,belonging to the genus Diospyros,is one of the most common fruits with high edible and economic value.China has the largest cultivated area and annual production of persimmons in the world.Pollination-constant nonastringent(PCNA)persimmon,which has great advantages of natural deastringency and direct edibility,has been a key target for industry development and variety selection worldwide.However,there are still many challenges in the development of persimmons in China;for example,the ineffective cost of artificial deastringency treatment of persimmons,laborious breeding of fine varieties of PCNA persimmon,and severe symptoms of delayed graft-incompatibility.This review summarizes the current status and development of persimmons in China.The current progress on the removal of astringency in persimmons,screening of rootstocks with wide compatibility,and the breeding process of PCNA persimmon is highlighted.This review will help promote the breeding of excellent persimmon varieties and the sustainable development of the persimmon industry in China.