Comparative Analysis on Fruit Qualities of 7 Litchi Varieties from Vietnam

[Objective] The aim was to screen litchi varieties suitable for local production in Vietnam. [Method] The fruit botanical and quality characteristics of the seven litchi varieties introduced into Northern Mountainous Agriculture and Forestry Science Institute of Vietnam Academy of Agriculture Sciences were compared and analyzed. [Result] Three varieties with good general qualities including Lai Phu Ho,Thach Binh and Hung Long which were suitable to be cultivated in the local area were selected. In addition,Phu Dong was the available,early-maturing germplasm resource. [Conclusion] This research will provide reference for litchi production and breeding in northern mountainous area.

Comparative Analysis on Fruit Qualities of Longan Varieties form Vietnam

[Objective] The aim was to screen longan varieties suitable for local production in Vietnam.[Method] The fruit botanical characteristics and quality characteristics of longan varieties introduced into Northern Mountainous Agriculture and Forestry Science Institute of Vietnam Academy of Agriculture Sciences were compared and analyzed.[Result] Two varieties with good general qualities including PMP6 and PHS1-1 which were suitable to be cultivated in the local area were selected.In addition,Phu Dong was the available processed germplasm resource.[Conclusion] This research will provide reference for longan production and breeding in Northern Mountainous.

Investigation of Punica granatum L.Germplasm Resources in Binchuan and Comparative Analysis of Major Fruit Qualities

[Objective] This study aimed to provide a basis for enriching the Punica granatum L. germplasm resources through investigating Punica granatum L. vari- eties in Binchuan. [Method] In this study, biological traits of Punica granatum L. vari- eties in Binchuan （including two local varieties-＇Binchuan Red Coat＇ and ＇Binchuan Green Coat＇, ＇Cyan Coat and Soft Seeds＇ and ＇Little Red Coat＇ introduced from Huili, Sichuan, ＇Acid Pomegranate＇ introduced from Shandong Province and ＂Ma Pomegranate＂ from Fengqiu, Henan） were investigated and their major fruit qualities were also analyzed. [Result] ＂Cyan Coat and Soft Seeds＇ and ＂Ma Pomegranate＇ grew well with good fruit quality, which adapted well to the climate and environment in Binchuan; ＂Little Red Coat＇ showed average performance in growth and major fruit qualities with inferior flavour; ＂Binchuan Red Coat＇ and ＇Binchuan Green Coat＇ also showed average performance in major fruit qualities and and inferior flavour; ＇Acid Pomegranate＇ grew while was inferior in flavour. [Conclusion] This study pro- vides references for presenting the directions for studies of P. granatum L. germplasm resources and determining the genetic relationship among germplasm resources, as well as breeding, introduction and cultivation of P. granatum L., further providing a variety basis for pomegranate production.

Effects of Different Litchi Rootstocks on Phonological Phase and Fruit Qualities of Grafted Jingganghongnuo

Phonological period and fruit quality of Jingganghongnuo （JGHN） grafted on the rootstocks of Feizixiao （FZX）, Heiye （HY） and Huaizhi （HZ） respectively were recorded and comparatively studied from 2015 to 2017. The results showed that the whitish millets and flowering stage of JGHN grafted on FZX and HY rootstocks were respectively 3-17 days and 1-3 days earlier than those on HZ. While the fruit maturation stage was 5-7 days ahead of in the same comparative situation. Compared to fruits grafted on HZ, mean fruit weight of JGHN grafted on HY and FZX were 38.1% and 35.8% bigger respectively than that on HZ. In addition, more closely heart-shaped and brighter pericarp color of JGHN fruit were observed with rootstock of HZ than that with other two kinds of rootstocks. In terms of aborted-seed rates of JGHN, average value with rootstock FZX was 81.7%, which was 58.0% higher than that with HY, and 2.49 times of those with HZ. Vc content of JGHN grafted on HY and FZX were 30.47 and 25.86 mg/100 g respectively, significantly higher than that grafted on HZ. TSS and TA of JGHN grafted on HZ were 17.8% and 0.14%, both were obviously higher than that grafted on FZX and HY.

Genome wide association analysis identifies candidate genes for fruit quality and yield in Actinidia eriantha

Quality and yield are the primary concerns in kiwifruit breeding,but research on the genetic mechanisms of fruit size,shape,and ascorbic acid(ASA)content is currently very limited,which restricts the development of kiwifruit molecular breeding.In this study,we obtained a total of 8.88 million highly reliable single nucleotide polymorphism(SNP)markers from 140 individuals from the natural hybrid offspring of Actinidia eriantha cv.‘White’using whole genome resequencing technology.A genome-wide association study was conducted on eight key agronomic traits,including single fruit weight,fruit shape,ASA content,and the number of inflorescences per branch.A total of 59 genetic loci containing potential functional genes were located,and candidate genes related to single fruit weight,fruit length,ASA content,number of inflorescences per branch and other traits were identified within the candidate interval,such as AeWUSCHEL,AeCDK1(cell cycle dependent kinase),AeAO1(ascorbic oxidase)and AeCO1(CONSTANS-like 4).After constructing an RNAi vector for AeAO1 and injecting it into the fruit of cv.‘Midao 31’to interfere with the expression of the AeAO1 gene,the results showed that the activity of ascorbic oxidase in the fruit of‘Midao 31’significantly decreased,while the content of ASA significantly increased.This study provides valuable insights into the genetic basis of variation in A.eriantha fruit traits,which may benefit molecular marker-assisted breeding efforts.

A novel histone methyltransferase gene Cg SDG40 positively regulates carotenoid biosynthesis during citrus fruit ripening

The flesh color of pummelo(Citrus maxima)fruits is highly diverse and largely depends on the level of carotenoids,which are beneficial to human health.It is vital to investigate the regulatory network of carotenoid biosynthesis to improve the carotenoid content in pummelo.However,the molecular mechanism underlying carotenoid accumulation in pummelo is not fully understood.In this study,we identified a novel histone methyltransferase gene,CgSDG40,involved in carotenoid regulation by analyzing the flesh transcriptome of typical white-fleshed pummelo,red-fleshed pummelo and extreme-colored F1 hybrids from a segregated pummelo population.Expression of CgSDG40 corresponded to flesh color change and was highly coexpressed with CgPSY1.Interestingly,CgSDG40 and CgPSY1 are located physically adjacent to each other on the chromosome in opposite directions,sharing a partially overlapping promoter region.Subcellular localization analysis indicated that CgSDG40 localizes to the nucleus.Overexpression of CgSDG40 significantly increased the total carotenoid content in citrus calli relative to that in wild type.In addition,expression of CgPSY1 was significantly activated in overexpression lines relative to wild type.Taken together,our findings reveal a novel histone methyltransferase regulator,CgSDG40,involved in the regulation of carotenoid biosynthesis in citrus and provide new strategies for molecular design breeding and genetic improvement of fruit color and nutritional quality.

Pear genomes display significant genetic diversity and provide novel insights into the fruit quality traits differentiation

The pear(Pyrus spp.)is well known for diverse flavors,textures,and global horticultural importance.However,the genetic diversity responsible for its extensive phenotypic variations remains largely unexplored.Here,we de novo assembled and annotated the genomes of the maternal(PsbM)and paternal(PsbF)lines of the hybrid‘Yuluxiang'pear and constructed the pear pangenome of 1.15 Gb by combining these two genomes with five previously published pear genomes representing cultivated and wild germplasm.Using the constructed pangenome,we identified 21224 gene PAVs(Presence-absence variation)and 1158812 SNPs(Single Nucleotide Polymorphism)in the non-reference genome that were absent in the PsbM reference genome.Compared with SNP markers,PAV-based analysis provides additional insights into the pear population structure.In addition,some genes associated with pear fruit quality traits have differential occurrence frequencies and differential gene expression between Asian and European populations.Moreover,our analysis of the pear pangenome revealed a mutated SNP and an insertion in the promoter region of the gene PsbMGH3.1 potentially enhance sepal shedding in‘Xuehuali'which is vital for pear quality.PsbMGH3.1 may play a role in the IAA pathway,contributing to a distinct low-auxin phenotype observed in plants by heterologously overexpressing this gene.This research helps capture the genetic diversity of pear populations and provides genomic resources for accelerating breeding.

Differential Expression of Genes Related to Fruit Development and Capsaicinoids Synthesis in Habanero Pepper Plants Grown in Contrasting Soil Types

Habanero pepper(Capsicum chinense Jacq.)is a crop of economic relevance in the Peninsula of Yucatan.Its fruits have a high level of capsaicinoids compared to peppers grown in other regions of the world,which gives them industrial importance.Soil is an important factor that affects pepper development,nutritional quality,and capsaicinoid content.However,the effect of soil type on fruit development and capsaicinoid metabolism has been little understood.This work aimed to compare the effect of soils with contrasting characteristics,black soil(BS)and red soil(RS),on the expression of genes related to the development of fruits,and capsaicinoid synthesis using a transcriptomic analysis of the habanero pepper fruits.Plants growing in RS had bigger fruits and higher expression of genes related to floral development,fruit abscission,and softening which suggests that RS stimulates fruit development from early stages until maturation stages.Fruits from plants growing in BS had enrichment in metabolic pathways related to growth,sugars,and photosynthesis.Besides,these fruits had higher capsaicinoid accumulation at 25 days post-anthesis,and higher expression of genes related to the branched-chain amino acids metabolism(ketol-acid reductisomerase KARI),pentose phosphate pathway and production of NADPH(glucose-6-phosphate-1-dehydrogenase G6PDH),and proteasome and vesicular traffic in cells(26S proteasome regulatory subunit T4 RPT4),which suggest that BS is better in the early stimulation of pathways related to the nutritional quality and capsaicinoid metabolism in the fruits.

Effects of Different Rootstocks on the Growth and Fruit Quality of‘Huangjinmi’Grape in Hefei

[Objectives]This study was conducted to enrich grape varieties.[Methods]The growth and fruit quality of grape with different rootstock and scion combinations were compared and analyzed taking CR2,CR3 and CR9 as rootstocks and‘Huangjinmi’as grafted seedlings and own-rooted seedlings as control.[Results]The comprehensive scores of‘Huangjinmi’grape with different rootstock and scion combinations showed an order of HJM/CR9,HJM/CR2 and HJM/CR3 from high to low.The three rootstock and scion combinations obviously promoted the growth and adaptability of grape trees,increased fruit size and improved fruit quality.Through the quality analysis of untreated and treated fruits,HJM/CR9 was superior to ZGM.Different fruit management measures can be adopted for‘Huangjinmi’grape to produce fruit with different quality according to market demand.[Conclusions]This study has a guiding significance for screening grape varieties suitable for adverse environments such as high soil viscosity,high temperature and high humidity.

Effect of Various Citrus Rootstock-scion Combinations on Tree Growth,Fruit Quality,and Photosynthetic Characteristics under Red Loam Soil Conditions

[Objectives]To investigate the effects of 15 distinct citrus rootstock-scion combinations on tree growth,fruit quality,and photosynthetic characteristics under red loam soil conditions and provide a theoretical foundation for the selection of appropriate citrus rootstock-scion combinations in the Zhaoqing region.[Methods]A total of 15 citrus rootstock-scion combinations were utilized as test materials for a comprehensive analysis of their phenological periods(budding,flowering,and fruiting),tree growth indicators(tree height,crown diameter,and growth),and fruit quality(appearance quality and intrinsic quality).The photosynthetic characteristics of the test materials,including the net photosynthetic rate(Pn),transpiration rate(Tr),water use efficiency(WUE),apparent quantum yield(AQY),and carboxylation efficiency(CE),were analyzed to determine their significance.Additionally,the leaf photosynthetic physiological indicators,such as soluble protein,specific leaf weight,chlorophyll,and carotenoids,were evaluated.[Results]There were notable differences observed in the phenological period,growth potential of trees,fruit quality,and photosynthetic characteristics among various citrus rootstock-scion combinations.The phenological periods exhibited variation contingent on the grafting varieties.In terms of tree growth potential,the Citrus tangerina Tanaka‘Hongju’and C.haniana Hort.‘Suanju’rootstocks demonstrated greater tree height,crown growth,and overall tree strength;however,they were also prone to excessive growth.Conversely,the C.limonia Osbeck‘Hongningmeng’and C.sinensis×P.trifoliata‘Zhicheng’rootstocks displayed medium growth potential,while the Poncirus trifoliate(L)Raf.‘Zhike’rootstock resulted in shorter trees.In terms of fruit quality,the single fruit weight of C.flamea Hort.‘Shatangju’ranged from 33 to 50 g,exhibiting a flat and round shape.The total soluble solids and titratable acid content of‘Shatangju’grafted onto the‘Zhike’rootstock were notably high.In contrast,the single fruit weight of C.haniana Hort.‘Chuntianju’varied between 65 and 81 g,characterized by a high flat round shape.The‘Suanju’rootstock demonstrated a higher sugar and acid content compared to other rootstocks.Additionally,the single fruit weight of C.nobilis Lour.‘Gonggan’ranged from 62 to 145 g,with the fruit shape being either round or oval.The soluble sugar and total soluble solids content associated with the‘Zhike’rootstock was also elevated.In relation to photosynthetic characteristics,the photosynthetic performance of the‘Shatangju’variety was superior when grafted onto the‘Zhike’and‘Hongju’rootstocks.Similarly,the‘Chuntianju’variety exhibited enhanced photosynthetic performance on the‘Zhike’,‘Zhicheng’,and‘Hongju’rootstocks.Furthermore,the‘Gonggan’variety demonstrated improved photosynthetic performance when grafted onto the‘Zhike’and‘Suanju’rootstocks.[Conclusions]Based on the characteristics of the red loam soil in the Zhaoqing region,the rootstocks‘Zhike’and‘Hongju’are conducive to the cultivation of the‘Shatangju’variety.Additionally,the rootstocks‘Zhike’,‘Zhicheng’,and‘Hongju’are optimal for the growth of the‘Chuntianju’variety,while the rootstocks‘Zhike’and‘Suanju’are appropriate for the growth of the‘Gonggan’variety.

Study of Effects of Plant Growth Regulators on Fruit Quality of Table Grape

The effects of different treatments on the seedlessness and fruit quality of‘Miguang’table grape was studied by using plant growth regulators,gibberellin acid(GA 3)and forchlorfenuron(CPPU),under different concentrations and application time.The results showed that the effects of different treatments on the seedlessness and fruit quality were different.Seedless rate,cluster weight,berry weight,berry shape index,soluble solid content,total acid content,soluble solids to acidity ratio,pulling resistance,turgor pressure and flesh firmness without skin were comprehensively evaluated,as a result of which,the optimum treatment on‘Miguang’table grape was to apply with GA 320 mg/L+SM 200 mg/L at one week before bloom and GA 325 mg/L+CPPU 3 mg/L at two weeks after bloom.

Improvement of Wolfberry(Lycium barbarum L.)Fruit Yield and Quality and Enhancement of Soil Fertility by Nitrogen Reduction Combined with Organic Fertilizers

Excessive amounts of nitrogen(N)fertilizers are applied during wolfberry production,resulting in some soil problems as well as potential environmental risks in the Qinghai-Tibet Plateau.In this study,organic fertilizers were used to replace part of the N fertilizer in wolfberry fields with different fertility levels.N fertilizer rates had 0,50,100,150,200,and 250 g N/plant.Organic fertilizer rates had 0,2,4,6,8,and 10 kg organic fertilizer/plant.The experimental treatments included 6 combinations of N0M10,N50M8,N100M6,N150M4,N200M2,and control was N250M0.The results showed that in the high-fertility soils,combinations of N150M4,N100M6 and N50M8 treatments were increased in yields,fruit shape index,flavonoid content,total phenol content,mineral nutrient content,and antioxidant activity of wolfberry fruits.Also they were improved in soil fertility and decreased in residual nitrate through the soil depth of 0-300 cm.In the soil with less fertility,fruit yield,amino acid contents,flavonoids,total phenols,mineral nutrients and antioxidant activity of fruits were increased by the N200M2,N150M4 and N100M6 treatments and soil fertility was improved as well.Also more residual nitrate was found in the depth of 0-100 cm of soil with both chemical and organic fertilizer compared with the control.Therefore,in the Qinghai-Tibet Plateau,combining decreased N fertilizer with organic fertilizer rather than chemical fertilizer alone could help farmers achieve satisfactory yields and quality of wolfberry fruits and reduce the risk of nitrate leaching.In conclusion,50-150 g/plant of N fertilizer combined with 4-8 kg/plant of organic fertilizer in high-fertility gardens and 100-200 g/plant of N fertilizer combined with 2-6 kg/plant of organic fertilizer in low-fertility gardens are recommended for wolfberry cultivation.

Study and Application of Partial Least Squares Regression on Relationship between Soil Nutrient and Fruit Quality

[Objective] The objective of the study was to elucidate the duplicate collinearity diagnosis method for soil nutrient and provide basis for establishment of multiple regression model of relationship between independent variable and depen- dent variable in fruit trees. [Method] An investigation on soil nutrients and ＇Fuji＇ fruit quality was conducted at 153 commercial apple orchards in the production re- gions of 51 counties in China from 2011 to 2012. At first, the regression equation was used to do the duplicate collinearity diagnosis, and then the partial least squares regression was used to analyze the weights of different soil nutrients that affected the fruit quality and screen out main soil nutrients. [Result] The results showed the conditional number between soil nutrients was 61.31, and the correlation coefficient of soil pH and available calcium, iron was 0.82 and -0.824 respectively, which demonstrated that there was multicollinearity between various soil nutrient contents. The soil organic matter, total nitrogen, available potassium, available nitro- gen, available phosphorus, available zinc, available iron and available boron showed positive effect Ioadings on fruit quality, while the }oadings and weights of the effects of available calcium and pH on fruit quality were negative. The variable importance for projection method was adopted to get the orders of the effects of major soil nu- trients on fruit quality, which was in the order of soil available calcium, nitrogen, available iron, available phosphorous, organic matter and available boron. The solu- ble solid content of the fruit was affected by soil organic matter, available phospho- rus, available iron, available boron and soil pH. [Conclusion] This study provided an analysis method and theoretical basis for the study and analysis on the relationships between dependent variables and multi-objective optimization, as well as the effects of soil nutrients on fruit quality in fruit tree.

Effects of Microbial Fertilizer and Compound Feritlizer Mixed Application on Yield and Fruit Quality and Flowering and Fruit Setting of Following Year of Apple

In order to study the application effect of microbial fertilizer and compound fertilizer mixed application on microirrigation apple, three types of fertilizers were applied in spring which were urea（CK, 15 kg/plant）, microbial fertilizer（5.0 kg/plant）,microbial fertilizer and compound fertilizer mixed（each 2.5 kg/plant） to study the effect of different fertilizer treatments on yield, fruit quality, flowering and fruit setting of Xinshijie apple. The results showed that application of microbial fertilizer could increase the yield, fruit weight and fruit shape index, significantly increase the flowering rates and inflorescence fruit setting rate of following year, while reduce the fruit hardness and soluble solids content, and the effect of microbial fertilizer and compound fertilizer mixed application on increasing fruit weight and yield was higher than that of microbial fertilizer separate application, the effect of the two was not obvious in other aspects. Therefore, microbial fertilizer could be used instead of some chemical fertilizer and organic fertilizer in apple production to reach the aim of increasing yield and efficiency, and the effect of microbial fertilizer and compound fertilizer mixed application was best.

Effects of a Complex Amendment on the Quality of Cucumber Fruit under Cd Contamination Stress

Pot experiments were carried out to investigate the effects of a complex amendment on the soil organic matter content, pH, microbial quantity, Cd uptake and nutritional quality of the fruit of cucumber （Cucumis sativus L.） planted in two levels （CdCl2·2.5H2O mg/kg and 4 mg/kg） of Cd-contaminated soil in which different concentrations of complex amendments （0, 600, 900, 1 200 mg/kg） were added. The results showed that when applying 1 200 mg/kg amendment, the organic mat-ter content, bacterial number and total microorganism amounts in 2 and 4 mg/kg Cd-contaminated soil increased by 23.17% and 32.89%, 87.61% and 96.02%, 59.95% and 55.81%, respectively. When 900 mg/kg amendment was applied, the fungi number in 2 and 4 mg/kg Cd-contaminated soil reached the maximum, in-creasing by 137.50% and 106.72% respectively. However, applying the amendment had no significant effect on the pH of soil. The security and nutritional quality of cu-cumber fruits were obviously improved comparing with control. The Cd content in cucumber fruits decreased by 31.40% and 24.35%, respectively, in 2 and 4 mg/kg Cd-contaminated soil. Furthermore, Vc, soluble sugar and soluble fixation content in cucumber fruits of 2 and 4 mg/kg Cd-contaminated soil went up by 25.00% and 91.42%, 37.03% and 27.06%, 14.29% and 58.80%, respectively. lt was indicated that the complex amendment can obviously improve the quality of cucumber fruit and thus can be used in the in situ_repair of Cd-contaminated soil.

Correlation Analysis between Quality Characteristics and Fruit Mineral Element Contents in 'Fuji' Apples

[Objective] The aims were to explore the relationship between the contents of fruit mineral elements and quality features of the ＇Fuji＇ apple, screen major mineral elements of the fruit affecting fruit quality features, and set up optimum proposals of fruit mineral elements for good fruit qualities, so as to provide a theoretical basis for the reasonable orchard soil and foliar fertilizer applications to increase fruit quality and reduce the physiological diseases related to the ＇Fuji＇ apple. [Methods] The fruit mineral elements and quality indicators of ＇Fuji＂ apples were in- vestigated and analyzed, which were collected from the 153 commercial apple or- chards of ＂Fuji＇ apple located in 51 counties. The variable importance for projection （VlP） of partial least squares regression （PLS） method was used to analyze the model effect and weight analysis impact of the fruit mineral element contents to fruit quality, screen out major factors of fruit mineral elements influencing the different fruit qualities, and set up the regression equation of the fruit qualities and major fruit mineral elements. Linear programming was used to obtain optimum proposals of the fruit mineral elements to achieve good ＇Fuji＇ apple qualities. [Results] The mineral elements content and quality characteristics in ＂Fuji＇ apple fruit had great differences in the different produce regions in which the maximum content of nitro- gen, iron, zinc and boron in the ＇Fuji＇ fruit were12.06, 6.17, 7.7, and 10.08 times greater than the minimum respectively, and the differences for titratable acid and the SSC/TA ratio were 2.33 and 2.16 times respectively. The correlation analysis between the fruit mineral element contents and qualities showed that the nitrogen content of fruit had a significantly negative correlation with the soluble solid content, SSC/TA ratio and red color area, while the calcium and iron contents in the fruit were in significantly positive correlation with the soluble solid content and SSC/TA ratio. The model effect and weight analysis showed that the content of nitrogen and iron in the fruit had a greater influence on the integral fruit quality, followed by phosphorus, potassium and calcium. The variable importance for projection （VlP） technology of PLS found that the mean fruit weight was primarily affected by nitro- gen, phosphorus and potassium, and the soluble solid was primarily affected by ni- trogen, calcium and iron, while the red color area was primarily affected by nitro- gen, potassium, calcium, iron and zinc. The regression equation between fruit quality and mineral element contents showed that the mean fruit weight had a greater pos- itive effect coefficient with the content of phosphorus and potassium, and a greater negative effect coefficient with the content of nitrogen in the fruit. Moreover, the sol- uble solid had the largest negative effect coefficient with nitrogen and largest posi- tive effect coefficient with calcium and iron in the fruit. [Conclusion] The maximum content of soluble solid and titratable acid were 1.5 times more than the minimum, and nitrogen, iron, zinc and boron were 6 times more than in the ＇Fuji＇ apple fruit in the different produce regions. Therefore, it is a key technological measure to improve the overall qualities of the ＂Fuji＇ apple by decreasing the content of nitrogen, and increasing the contents of iron, phosphorus, potassium and calcium in the fruit.

Effects on Sucrose Metabolism,Dry Matter Distribution and Fruit Quality of Tomato Under Water Deficit

Four irrigation treatments were designed with 2,4,6 and 8 d intervals to irrigate, respectively. Watering was stopped when the reading of the moisture tension sensor reached zero. The results indicated that glucose and fructose content of tomato's fruit were increased but sucrose content was decreased with fruit growth and development. In different stages, carbohydrate content of tomato fruit in the treatment 3 was the highest, in the treatment 2 was higher, and in the other treatments was the lowest. SS(sucrose synthase)activity was decreased but SPS(sucrose phosphate synthase)activity was increased with development of tomato. SS and SPS activity were increased but acid invertase and neutral invertase activity of ripe stage were decreased under deficit irrigation. Glucose and fructose content were increased in leaves of tomato under water deficit. Soluble sugars, organic acid and the ratio of sugar/acid in tomato fruits were increased and dry matter accumulation of plant was enhanced under water deficit. But the growth of fruits upside the plant and its dry matter accumulation were badly affected under water stress.

Advances in Genomic,Transcriptomic,and Metabolomic Analyses of Fruit Quality in Fruit Crops

Fruit quality is the main factor determining market competitiveness;it represents the combination of fruit flavor,color,size,and the contents of aromatic and bioactive substances.Research on the genetic basis of fruit quality can provide new information about fruit biology,promote genomic-assisted breeding,and provide technological support for the regulation of fruit quality via habitat selection and/or the control of environmental conditions.High-throughput sequencing is a powerful research method for studying fruit quality traits,and reference genome sequences for many important fruit crops have provided vast amounts of genomic data.To study fruit quality,it is important to select appropriate omics strategies and to analyze omics data meaningfully.Here,we summarize genomic mechanisms of fruit quality formation:gene duplication,transposable element insertion,structural variations and genome methylation in functional genes.We review the genomic,transcriptomic,and metabolomic strategies that have been used to study the genetic basis of fruit quality traits.We also describe some of the genes associated with fruit traits;these genes are a valuable resource for genomics-assisted breeding and are useful models for deciphering the mechanisms of agronomic traits,such as fruit color,size,hardness,aroma components,sugar and acid content.Finally,to maximize the application of omics information,we propose some further directions for research using omics strategies.

Peach yield and fruit quality is maintained under mild deficit irrigation in semi-arid China

We conducted a two-year study of deficit irrigation impact on peach yield and quality in semi-arid northwest China. Over two years, four-year-old peach trees were irrigated at 100, 75, 50 and 25% of peach evapotranspiration （ETc）, here, ETc= Coefficient （Kc）×Local reference evapotranspiration （ET0）. During the April-July fruit production season we measured root zone soil water depletion, sap flow velocity, net photosynthetic rate （Pn）, transpiration rate （Tr）, stomatal conductance （Gs）, water use efficiency （WUE=Pn/Tr）, fruit quality, and yield under a mobile rain-out shelter. Increased soil water depletion reasonably mirrored decreasing irrigation rates both years, causing progressively greater water stress. Progressive water stress lowered Gs, which in turn translated into lower T as measured by sap flow. However, mild deficit irrigation （75% ETc） constricted T more than Pn. Pn was not different between 100 and 75% ETc treatments in both years, and it decreased only 5-8% in June with higher temperature than that in May with cooler temperature. Concurrently under 75% ETc treatment, was reduced, and WUE was up to 13% higher than that under 100% ETc treatment. While total fruit yield was not different under the two treatments, because 75% ETc treatment had fewer but larger fruit than 100% ETc trees, suggesting mild water stress thinned fruit load. By contrast, sharply decreased T and Pn of the driest treatments （50 and 25% ETo） increased WUE, but less carbon uptake impacted total fruit yield, resulting 13 and 33% lower yield compared to that of 100% ETc treatment. Irrigation rates affected fruit quality, particularly between the 100 and 75% ETc trees. Fewer but larger fruit in the mildly water stressed trees （75% ETc） resulted in more soluble solids and vitamin C, firmer fruit, and improved sugar：acid ratio and fruit color compared to the 100% ETo treatment. Overall, trees deficit irrigated at 75% ETc maintained yield while improving fruit quality and using less water.

Manual thinning increases fruit size and sugar content of Citrus reticulata Blanco and affects hormone synthesis and sugar transporter activity

Manual fruit thinning(MFT)in fruit trees has been previously shown to increase fruit size and enhance fruit quality,but the effect of MFT on Ponkan(Citrus reticulata Blanco)and the underlying mechanisms remain poorly understood.In this study,efforts were made to elucidate how MFT influences the fruit quality of Ponkan.The results showed that MFT substantially increased fruit size and elevated fruit total soluble solids in comparison with the fruit from the unthinned trees(used as control).Expression analyses demonstrated that m RNA abundance of three important sugar transporter genes,including CrSUT1,CrSTP1 and CrTMT1,was evidently elevated in the flesh of thinned fruit when compared with those of the control.In addition,MFT prominently up-regulated the transcript levels of various auxin and gibberellin(GA)biosynthesis and signaling genes,including CrYUC6,CrAUX/IAA,CrGA20ox1 and CrGA3ox1.Concurrently,the contents of endogenous IAA and GA3,measured at 90 d after fruit thinning,were notably elevated in the fruit from trees with the thinning treatment relative to the control,although no difference was detected in the two groups before the thinning manipulation.Taken together,these results indicate that manual fruit thinning could greatly improve fruit quality,which may be attributed to promoting fruit expansion due to the increased auxin levels and expediting sugar accumulation through the up-regulation of sugar transporter genes.