Affect Fruit Quality Research Articles

Potassium Silicate Improves Salinity Resistant and Affects Fruit Quality in Two Strawberry Cultivars Grown Under Salt Stress

ABSTRACTThe response of ‘Kurdistan’ and ‘Paros’ strawberry cultivars to potassium silicate (K2O3Si) under sodium chloride (NaCl) salinity stress was studied in terms of vegetative parameters, sodium (Na) and potassium (K) content and fruit quality. K2O3Si could recover dry mass distribution of NaCl-stressed strawberry organs. Kurdistan cultivar tended to keep higher dry weight of leaves to maintain its photosynthetic apparatus activity. Inhibitory impact of K2O3Si on Na uptake of leaf was more obvious than root. Implementation of K2O3Si in some cases increased Total Soluble Solid (TSS) and Titratable Acidity (TA), which are the main factors determining taste of strawberry fruit. Furthermore, phenols and flavonoids were increased in Paros cultivar by effect K2O3Si under saline and non-saline conditions, respectively. Overall, our data suggest that silicon supply in strawberry plants not only could be used as a routine strategy to maintain growth and yield under salinity but also it could be beneficial for improvement of fruit quality attributes and health-related constituents.Abbreviations: ANOVA: Analysis of Variance; CRD: Completely Randomized Design; DPPH: 1,1-Diphenyl-2-picryl-hydrazyl; FF: Fruit Firmness; LSD: Least Significant Difference; PAL: Phenyl Alanine Ammonia Lyase; ROS: Reactive Oxygen Species; TSS: Total Soluble Solid; TAA: Total Antioxidant Activity; TA: Titratable Acidity; TAC: Total Anthocyanin; TF: Total Flavonoids; TP: Total Phenolics;

Differential color development and response to light deprivation of fig (Ficus carica L.) syconia peel and female flower tissues: transcriptome elucidation

BackgroundColor directly affects fruit quality and consumer preference. In fig syconia, the female flower tissue is contained in a receptacle. Anthocyanin pigmentation of this tissue and the peel differs temporally and spatially. A transcriptome study was carried out to elucidate key genes and transcription factors regulating differences in fig coloring.ResultsAnthocyanins in the female flower tissue were identified mainly as pelargonidin-3-glucoside and cyanidin-3-rutinoside; in the peel, the major anthocyanins were cyanidin 3-O-glucoside and cyanidin-3-rutinoside. Anthocyanin content was significantly higher in the female flower tissue vs. peel before fig ripening, whereas at ripening, the anthocyanin content in the peel was 5.39 times higher than that in the female flower tissue. Light-deprivation treatment strongly inhibited peel, but not female flower tissue, anthocyanin pigmentation. RNA-Seq revealed 522 differentially expressed genes (recruited with criteria log2 ≥ 2 and P < 0.05) at fig ripening, with 50 upregulated and 472 downregulated genes in the female flower tissue. Light deprivation upregulated 1180 and downregulated 856 genes in the peel, and upregulated 909 and downregulated 817 genes in the female flower tissue. KEGG enrichment revealed significantly changed expression in the phenylpropanoid-biosynthesis and flavonoid-biosynthesis pathways in the peel, but not in the female flower tissue, with significant repression of FcCHS, FcCHI, FcF3H, FcF3’H, FcDFR and FcUFGT transcripts. Light deprivation led to differential expression of 71 and 80 transcription factor genes in the peel and female flower tissue, respectively. Yeast one-hybrid screen revealed that FcHY5 and FcMYB114 bind the promoter regions of FcCHS and FcDFR, respectively in the flavonoid-biosynthesis pathway.ConclusionsPhenylpropanoid- and flavonoid-biosynthesis pathways were differentially expressed spatially and temporally in the peel and female flower tissue of fig syconia; pathway expression in the peel was strongly regulated by light signal. Differentially expressed transcription factors were recruited as candidates to screen important expression regulators in the light-dependent and light-independent anthocyanin-synthesis pathway. Our study lays the groundwork for further elucidation of crucial players in fig pigmentation.

Light exposure affects fruit quality in different strawberry cultivars under field conditions

Strawberry (Fragaria x ananassa Duch.) fruits are highly appreciated worldwide because of their flavour and their content on healthy-related compounds. Most of these compounds have antioxidant properties and photo-protective activities involved in plant response against environmental constrains, including light availability. Thus, fruit quality might be affected by variation in environmental factors such as light conditions. A field experiment, performed under conventional cropping conditions, was designed for assessing the effects of the light exposure level of fruits on fruit quality parameters in four strawberry cultivars (‘Sabrina’, ‘Fortuna’, ‘Splendor’ and ‘Primoris’) during a cropping season. To assess to what extent strawberry genotypes are able to modulate their fruit quality traits in response to light conditions, a plasticity index was calculated for a quantitative estimation of the amount of phenotypic change induced by the environment (i.e. light-exposure) on the different strawberry cultivars.Results showed that proportion of exposed fruits compared to non-exposed ones was similar in all cultivars despite their differences in canopy size. This was achieved by modulating peduncle length: the higher the canopy size, the higher the peduncle length. This work also demonstrates that light incidence influences strawberry fruit quality - flavour and antioxidant content- and that the responsiveness to light conditions, estimated by the plasticity index, of strawberry fruits is genotype dependent. These results are suggesting differences among cultivars in the ability of adapting to variable light environments, and their significance in a breeding context and from an applied point of view is discussed.

Investigation and Prevention of Cork Spot Disorder in ‘Akizuki’ Pear (Pyrus pyrifolia Nakai)

‘Akizuki’ (Pyrus pyrifolia Nakai) is a dominant Asian pear cultivar with gradually increasing cultivation area in Shandong province. However, this cultivar is found susceptible to cork spot disorder in recent years. In this study, we explored the physiological-biochemical mechanism of cork spot disorder in pear fruit, and investigated the effectiveness of spraying calcium (Ca), boron (B) solution or prohexadione calcium (P-Ca) on cork spot incidence. Cork spotted fruit had the characteristics of significantly larger fruit size with shorter fruit pedicels. Compared with normal fruit, cork spotted fruit had lower content of total soluble solids, soluble and reducing sugar, and vitamin C. In addition, cork spotted fruit accumulated much higher levels of N and Mg, and lower levels of K and P. However, Ca deficiency was not observed in cork spotted fruit, on the contrary, we determined high concentrations of Ca and free Ca2+ in disordered fruit. At the same time, the ratios of K/Ca, Mg/Ca, and (K+Mg)/Ca were significantly lower in cork spotted fruit as compared with normal fruit. Among all treatments, spraying with 3500 times dilution of P-Ca at 15-day intervals from 30 to 90 days after full bloom showed promise for reducing cork spot incidence in ‘Akizuki’ pear without affecting fruit quality attributes. This research herein reveals the physiological-biochemical characteristic of cork spot disorder, and implicates P-Ca as a potential tool to reduce cork spot incidence in Asian pear cultivar Akizuki.

Solanum lycopersicum GOLDEN 2-LIKE 2 transcription factor affects fruit quality in a light- and auxin-dependent manner.

Plastids are organelles responsible for essential aspects of plant development, including carbon fixation and synthesis of several secondary metabolites. Chloroplast differentiation and activity are highly regulated by light, and several proteins involved in these processes have been characterised. Such is the case of the GOLDEN 2-LIKE (GLK) transcription factors, which induces the expression of genes related to chloroplast differentiation and photosynthesis. The tomato (Solanum lycopersicum) genome harbours two copies of this gene, SlGLK1 and SlGLK2, each with distinct expression patterns. While the former predominates in leaves, the latter is mainly expressed in fruits, precisely at the pedicel region. During tomato domestication, the selection of fruits with uniform ripening fixed the mutation Slglk2, nowadays present in most cultivated varieties, what penalised fruit metabolic composition. In this study, we investigated how SlGLK2 is regulated by light, auxin and cytokinin and determined the effect of SlGLK2 on tocopherol (vitamin E) and sugar metabolism, which are components of the fruit nutritional and industrial quality. To achieve this, transcriptional profiling and biochemical analysis were performed throughout fruit development and ripening from SlGLK2, Slglk2, SlGLK2-overexpressing genotypes, as well as from phytochrome and hormonal deficient mutants. The results revealed that SlGLK2 expression is regulated by phytochrome-mediated light perception, yet this gene can induce chloroplast differentiation even in a phytochrome-independent manner. Moreover, auxin was found to be a negative regulator of SlGLK2 expression, while SlGLK2 enhances cytokinin responsiveness. Additionally, SlGLK2 enhanced chlorophyll content in immature green fruits, leading to an increment in tocopherol level in ripe fruits. Finally, SlGLK2 overexpression resulted in higher total soluble solid content, possibly by the regulation of sugar metabolism enzyme-encoding genes. The results obtained here shed light on the regulatory network that interconnects SlGLK2, phytohormones and light signal, promoting the plastidial activity and consequently, influencing the quality of tomato fruit.

PbrMYB169 positively regulates lignification of stone cells in pear fruit.

Stone cells negatively affect fruit quality because of their firm and lignified cell walls, so are targets for reduction in pear breeding programmes. However, there is only limited knowledge of the molecular mechanisms underlying the formation of stone cells. Here, we show that PbrMYB169, an R2R3 MYB transcription factor, of Pyrus bretschneideri positively regulates lignification of stone cells in pear fruit. PbrMYB169 was shown to be co-expressed with lignin biosynthesis genes during pear fruit development, and this co-expression pattern was coincident with stone cell formation in the fruit of Pyrus bretschneideri 'Dangshansuli'. The PbrMYB169 expression level was also positively correlated with stone cell content in 36 pear cultivars tested. PbrMYB169 protein significantly activated the promoter of lignin genes C3H1, CCR1, CCOMT2, CAD, 4CL1, 4CL2, HCT2, and LAC18 via binding to AC elements [ACC(T/A)ACC] in these promoters. Furthermore, overexpression of PbrMYB169 in transgenic Arabidopsis plants enhanced the expression of lignin genes, and increased lignin deposition and cell wall thickness of vessel elements, but did not change the ratio of syringyl and guaiacyl lignin monomers. In conclusion, PbrMYB169 appears to be a transcriptional activator of lignin biosynthesis and regulates secondary wall formation in fruit stone cells. This study advances the understanding of the regulation of lignin biosynthesis and provides valuable molecular genetic information for reducing stone cell content in pear fruit.

High Storage Humidity Affects Fruit Quality Attributes and Incidence of Fruit Cracking in Cold-stored ‘Royal Gala’ Apples

‘Royal Gala’ apples can be susceptible to the incidence of fruit cracking and senescent flesh breakdown during cold storage. Because the development of these physiological disorders in other cultivars can be influenced by humidity during storage, the objective of this study was to evaluate the effect of high storage humidity on fruit quality attributes and incidence of physiological disorders in cold-stored ‘Royal Gala’ apples. Fruit obtained from a commercial orchard were kept in cardboard boxes with or without a perforated polyethylene liner during and after cold storage. High storage humidity induced by the perforated polyethylene liner reduced fresh weight loss but enhanced the change of fruit circumference after cold storage. High storage humidity contributed the most reduction of cortex lightness (L*) and hue angle (ho) in stem-end cortex tissues during shelf life. Fruit stored with liners had reduced internal ethylene concentration (IEC) and outer cortex firmness after removal from storage compared with control fruit. Furthermore, high storage humidity prevented shriveling but provoked fruit cracking. The incidence and severity of flesh breakdown were further aggravated during shelf life, compared with cold storage, regardless of a liner application. Overall, maintaining high storage humidity by applying a perforated polyethylene liner can contribute to delaying fresh weight loss, reducing IEC, and preventing fruit shriveling but can enhance cortex tissue browning, loss of flesh firmness, and incidence of fruit cracking during cold storage and shelf life.

Microsensor for limonin detection: An indicator of citrus greening disease

Limonin is a biomolecule which is responsible for the bitter taste in citrus fruits such as oranges, grapes etc. The abnormally high level of limonin is indicative of citrus greening disease which results in stunted tree growth and affects fruit quality in terms of nutritional value, taste, texture and aroma. Therefore, quantification and detection of limonin is crucial for an early management of citrus greening disease to save the multibillion dollar citrus industry. To this end, an organic electrochemical transistor (OECT) functionalized with Ceria Nanoparticles (CNPs) as transducer has been developed to detect ultralow concentration of limonin. The device exhibited high sensitivity (detection limit: 10 nM) and selectivity towards limonin with response time in seconds. The detection is attributed to the switching of Ce3+ to Ce4+ at the gate electrode which decreases the overall effective gate voltage resulting in an increase in the output current. The increase in output current was observed in transfer characteristics as well as time-current curve. In-situ spectro-electrochemical studies were also performed to analyse the change in oxidation state of CNPs in the presence of limonin. This novel biosensor successfully detected the increase in limonin in infected juice samples as compared to healthy ones with a sensitivity of ∼10 μA/μM. A rapid, easy and on-site testing tool to detect and quantify the amount of limonin for an early detection of citrus greening disease has been demonstrated for the first time.

Interactive effects of elevated carbon dioxide and nitrogen availability on fruit quality of cucumber (Cucumis sativus L.)

Elevated CO2 and high N promote the yield of vegetables interactively, whilst their interactive effects on fruit quality of cucumber (Cucumis sativus L.) are unclear. We studied the effects of three CO2 concentrations (400 μmol mol−1 (ambient), 625 μmol mol−1 (moderate) and 1 200 μmol mol−1 (high)) and nitrate levels (2 mmol L−1 (low), 7 mmol L−1 (moderate) and 14 mmol L−1 (high)) on fruit quality of cucumber in open top chambers. Compared with ambient CO2, high CO2 increased the concentrations of fructose and glucose in fruits and maintained the titratable acidity, resulting in the greater ratio of sugar to acid in moderate N, whilst it had no significant effects on these parameters in high N. Moderate and high CO2 had no significant effect on starch concentration and decreased dietary fiber concentration by 13 and 18%, nitrate by 31 and 84% and crude protein by 19 and 20% averagely, without interactions with N levels. The decreases in amino acids under high CO2 were similar, ranging from 10–18%, except for tyrosine (50%). High CO2 also increased the concentrations of P, K, Ca and Mg but decreased the concentrations of Fe and Zn in low N, whilst high CO2 maintained the concentrations of P, K, Ca, Mg, Fe, Mn, Cu and Zn in moderate and high N. In conclusion, high CO2 and moderate N availability can be the best combination for improving the fruit quality of cucumber. The fruit enlargement, carbon transformation and N assimilation are probably the main processes affecting fruit quality under CO2 enrichment.

Canopy factors influencing sunburn and fruit quality of Japanese plum (Prunus salicinaLindl.)

High irradiance and high temperatures decrease Japanese plum (Prunus salicina Lindl.) quality by causing sunburn. We manipulated orchard conditions to determine how resultant light and temperature affected fruit quality and sunburn. In the 2013/14 season, early summer pruning, late pruning and a no pruning control were applied in an ‘African Delight’ plum orchard trained to a staggered V trellising system in the Western Cape Province of South Africa. In 2014/15, 20% shade net was incorporated during the hottest part of the season in a split plot design. Shade net and a no shade net control formed the main plots while pruning treatments were subplots. Photosynthetic photon flux (PPF), fruit surface temperature (FST) and sunburn were progressively assessed on two hourly intervals on typically hot days for upper, mid and lower canopy positions. PPF and FST generally decreased from top to bottom of the canopy. Upper canopy positions had bigger and softer fruit with higher sunburn incidence and higher total soluble solids (TSS). Fruit that developed sunburn received >50% PPF of full sun on average while average FST exceeded 35°C. Early summer pruning improved early light penetration but enabled vegetative regrowth for filtered light during the hottest part of the season resulting in bigger and redder fruit with higher TSS and low sunburn. Delayed pruning increased sunburn with no increase in fruit size, while the control delayed fruit maturity and reduced fruit size. The shade net reduced sunburn caused by delayed summer pruning. While it was apparent that proper timing of orchard light manipulation is essential, the use of shade net still has to be evaluated over the entire growing season to ascertain its full value.

Bud load management on table grape yield and quality – cv. Sugrathirteen (Midnight Beauty®)

ABSTRACT Viticulture is an activity of great economic and social importance in the Submedium region of the Sao Francisco River Valley, with emphasis on table grape and wine production. With the increasing expansion of the viticulture, a growing number of alternatives that do not affect fruit quality have been studied to maximize table grape yield, such as pruning and load adjustment. The aim of the present study was to evaluate the influence of different bud loads on canopy management to enable the marketable and economic production of cv. Sugrathirteen (Midnight Beauty®) in the submedium region ofthe Sao Francisco River Valley. This study was carried out for two years (2014/2015) in an experimental area for the introduction of new cultivars patented by Prodomo Farm in the municipality of Petrolina, Pernambuco, Brazil. The experiment was conducted in a randomized block factorial 2 × 5 design, with two seasons and 5 treatments, 6, 8, 10, 12 and 14 buds short_textwhich correspond toshort_text 17, 23, 29, 34 and 40 buds·m–2 short_textrespectivelyshort_text, distributed in 4 plots, considering five plants per replicate. Our results show that pruning seasons significantly affected sprouting percentage. However, the difference in bud load influenced this variable, with higher values in the pruning at 14 buds in both seasons. According to the results, the selection of pruning system according to bud load and to genetic features of the cultivar, and their interaction with the environment, produced higher yields in pruning with 10 buds, without negatively affecting grape quality.

Breeding Trait Priorities of the Cranberry Industry in the United States and Canada

Informed assessment of priority genetic traits in plant breeding programs is important to improve the efficiency of developing cultivars suited to current climate and industry needs. The efficiency of genetic improvement is critical for perennial crops such as cranberries, as they usually involve more resources, time, and funding compared with other crops. This study investigated the relative importance of cranberry producers’ preferences for breeding traits related to fruit quality, productivity, plant physiology, and resistance to biotic and abiotic stresses. Industry responses revealed that fruit characteristics affecting fruit quality, including firmness, fruit size and anthocyanin content, and resistance to fruit rot, were the most desired traits in new cranberry cultivar release. These traits have the potential to increase the quality standards needed to process high-value sweetened dried cranberry products, positively affecting price premiums received by producers, which is critical for the economic viability of the cranberry industry. Our findings will be useful to breeders and allied scientists seeking to develop an advanced DNA-based selection strategy that would impact the global cranberry industry.

Molecular and Genetic Bases of Fruit Firmness Variation in Blueberry—A Review

Blueberry (Vaccinium spp.) has been recognized worldwide as a valuable source of health-promoting compounds, becoming a crop with some of the fastest rising consumer demand trends. Fruit firmness is a key target for blueberry breeding as it directly affects fruit quality, consumer preference, transportability, shelf life, and the ability of cultivars to be machine harvested. Fruit softening naturally occurs during berry development, maturation, and postharvest ripening. However, some genotypes are better at retaining firmness than others, and some are crispy, which is a putatively extra-firmness phenotype that provides a distinct eating experience. In this review, we summarized important studies addressing the firmness trait in blueberry, focusing on physiological and molecular changes affecting this trait at the onset of ripening and also the genetic basis of firmness variation across individuals. New insights into these topics were also achieved by using previously available data and historical records from the blueberry breeding program at the University of Florida. The complex quantitative nature of firmness in an autopolyploid species such as blueberry imposes additional challenges for the implementation of molecular techniques in breeding. However, we highlighted some recent genomics-based studies and the potential of a QTL (Quantitative Trait Locus) mapping analysis and genome editing protocols such as CRISPR/Cas9 to further assist and accelerate the breeding process for this important trait.

Peach Scab

There are many peach diseases that can affect fruit quality and the marketability of the produce. Blemishes to the skin or within the flesh can be a reason to reject an entire fruit load or significantly reduce the purchasing price. Peach scab is a disease caused by the fungus Cladosporium carpophilum (Figure 1). The pathogen can infect twigs, leaves, and fruits, where it can cause lesions that can affect fruit quality, marketability, and in extreme cases can cause cracking of the fruit and premature fruit drop. Peach scab is typical during periods of humid weather because rain splashes the conidia (asexual spores) from the fungus between leaves, twigs, and fruit in the tree canopy, which spreads the disease. This pathogen can infect other fruits and nuts within the Prunus species, like almonds, apricots, nectarines, and plums. This 6-page fact sheet is a minor revision written by Daniel Mancero-Castillo, Ali Sarkhosh, Mercy Olmstead, and Phillip Harmon, and published by the Horticultural Sciences Department, August 2018. HS1249/HS1249: Peach Scab (ufl.edu)

The effect of pre-harvest wind damage on post-harvest quality of ‘Triumph’ persimmon fruit

The post-harvest quality of ‘Triumph’ persimmon fruits grown in the Western Cape, South Africa varies with seasons. Poor post-harvest fruit quality is assumed to be associated with seasons that are characterized by violent wind occurrences. This study was carried out to investigate if pre-harvest wind damage to trees and fruit affects post-harvest fruit quality. The study was conducted in the 2012 and 2013 seasons. Wind and its damage were simulated by blowing trees with a mist blower, shaking trees, defoliating half of the trees and twisting fruit stalks 10 days prior to harvest. Fruit quality was evaluated at harvest, after 6½ weeks storage and after four days shelf-life. Simulated wind and its damage affected fruit quality at different stages during storage. Defoliation and twisting of fruit stalks increased soft fruits from 0% at harvest to 28% after storage in the 2012 season. Defoliation and blowing trees decreased total soluble solids after shelf-life in both seasons. Twisting fruit stalks delayed fruit colour development after storage and after shelf-life in the 2013 season. Blowing trees increased soft fruits to around 50% after shelf-life in both seasons. It can, therefore, be concluded that, post-harvest quality of ‘Triumph’ persimmon fruits is negatively affected by pre-harvest wind damage.

Rootstock’s and scion’s impact on lemon quality in southeast Spain

Abstract In terms of growth, yield and fruit quality, three lemon varieties (‘Fino49’ F49, ‘Verna50’ V50 and ‘FinoElche’ FE) were tested on three new hybrid root stock selections (Forner-Alcaide 2324, Forner-Alcaide 418 and Forner-Alcaide 5). Yield was weighed within a nine year period and fruit quality was determined in two harvests. Tree size was similar on the Forner-Alcaide 5 and Forner-Alcaide 2324 rootstocks, but reduced by 50% on Forner-Alcaide 418. Forner-Alcaide 2324 and the Forner-Alcaide 5 rootstocks showed similar cumulative yield, while it was decreased by 66% in Forner-Alcaide 418. In all cases, ‘Verna50’ was the less efficient scion. Rootstock was found to significantly affect fruit quality variables. The Forner-Alcaide 418 rootstock induced the lowest peel thickness and peel percentage, but the highest juice content and colour index. Forner-Alcaide 5, together with Forner-Alcaide 418, showed the highest total soluble sugars. In conclusion, both the Forner-Alcaide 5 and Forner-Alcaide 2324 rootstocks generate standard tree size and high yield in the varieties tested, together with great fruit quality, being a suitable alternative for replacing C. macrophylla rootstock when used in lemon varieties. Forner-Alcaide 418 reduces tree size without decreasing yield efficiency and improves alternate-bearing of the harvest. Thus, it may have use in intensifying citrus production as it behaves as a dwarfing rootstock.

Effects of precooling time and 1-MCP treatment on ‘Bartlett’ fruit quality during the cold storage

Abstract ‘Bartlett’ is one of the consumer’s favorite pears due to its juicy, delicate texture, and excellent flavor; however, the short storage life of the fruit limits its market value. One main factor affecting fruit quality is the early peel yellowing. In this study, the effects of the delayed precooling and 1-MCP treatment on the fruit quality were investigated. For the delayed precooling treatment, the fruit were held at 20 °C for 0, 12, and 24 h before they were moved to a cold storage (−1 °C). For the 1-MCP treatment, the fruit were exposed to 1-MCP at 0.3 μL/L for 24 h in the cold storage. After 1-MCP treatment, all fruits were stored at −1 °C and evaluated over a 6-month period. Results showed that delayed precooling of the field harvested fruit significantly extended the fruit cooling rate. Treatment with 1-MCP significantly inhibited the fruit respiration and ethylene production, delayed fruit ripening capacity, retarded chlorophyll degradation and eliminated senescence scald; however, these effects were not observed in the non-1-MCP treated fruit. Expression of the ethylene synthesis genes (PcACS1, PcACS4, PcACS5, and PcACO1) and receptor genes (PcETR1, PcETR2, and PcERS) was dramatically increased by delayed precooling time, but their expression was suppressed by 1-MCP treatment. Two genes (PcACS5 and PcETR1) were hierarchical among controls 0, 12 and 24. In contrast, the PcACS2 gene was upregulated by 1-MCP. The transcription level of the chlorophyll degradation genes PcPPH, PcSGR1, PcRCCR, and PcNYC was increasing in the non-1-MCP treated fruit, but inhibited by 1-MCP treatment during the cold storage time and the inhibition level was negatively related to the delayed precooling time. The expression of PcPAO and PcCHL1 dramatically decreased in the non-1-MCP treatments and little effect of 1-MCP treatment on their expression was observed. In conclusion, 0 h of delayed precooling time or 1-MCP treatment prevented peel yellowing and extended storage life of ‘Bartlett’; howerver, 1-MCP treatment delayed fruit ripening and the fruit required 14 days at 20 °C to ripen following 4–6 months of storage.

Role of the tomato TAGL1 gene in regulating fruit metabolites elucidated using RNA sequence and metabolomics analyses.

Fruit ripening is a complex biological process affecting fruit quality. In tomato the fruit ripening process is delicately regulated by transcription factors (TFs). Among these, the TOMATO AGAMOUS-LIKE 1 (TAGL1) gene plays an important role in both the development and ripening of fruit. In this study, the TAGL1 gene was successfully silenced by virus-induced gene silencing technology (VIGS), and the global gene expression and metabolites profiles of TAGL1-silenced fruits were analyzed by RNA-sequence analysis (RNA-seq) and liquid chromatography–mass spectrometry (LC-MS/MS). The TAGL1-silenced fruits phenotypically displayed an orange pericarp, which was in accordance with the results expected from the down-regulation of genes associated with carotenoid synthesis. Levels of several amino acids and organic acids were lower in the TAGL1-silenced fruits than in the wild-type fruits, whereas, α-tomatine content was greatly increased (more than 10-fold) in the TAGL1-silenced fruits compared to wild-type fruits. The findings of this study showed that TAGL1 not only regulates the ripening of tomato fruits, but also affects the synthesis and levels of nutrients in the fruit.

The isolation of the IGT family genes in Malus × domestica and their expressions in four idiotype apple cultivars

IGT family genes share the highly conserved motif GφL-(A/T) IGT in domain II and play an essential role in plant form. The tree architecture of apple (Malus × domestica Borkh.) affects fruit quality and yield. However, little information is available regarding IGT family genes in apple. Apple cultivars of four ideotypes (columnar, tip bearer, spur, and standard) were selected to characterize IGT family genes. Four IGT family members named MdoTAC1a, MdoTAC1b, MdoLAZY1, and MdoLAZY2 were found in the apple genome, sharing four conserved domains. In addition, MdoLAZY1 and MdoLAZY2 contain a fifth domain (EAR motif) at the C-terminus. There was no difference in the coding sequences of each gene in the four cultivars, but several mutated sites were found in their promoters. The four genes displayed lower expression levels in all tested tissues and organs of the columnar cultivar than in the other three cultivars, while expression levels of MdoTAC1a and MdoTAC1b in shoot tips and vegetative buds were highest in the standard cultivar, followed by spur, tip bearing, and columnar cultivars in decreasing order. These results indicate that IGT gene promoters are of great importance in the development of apple tree architecture and lay a theoretical basis for developing gene-specific markers for marker-assisted selection in breeding programs.

Changes in cell wall pectins and their relation to postharvest mesocarp softening of “Hass” avocados (Persea americana Mill.)

The avocado is a climacteric fruit and begins a softening process after harvest. During ripening, the mesocarp changes in texture, and this affects fruit quality and cold storage capacity. Softening is commonly associated with cell wall disassembly in climacteric fruits. However, changes in the cell wall structure and composition during avocado softening are poorly understood. To understand this process, cell wall pectins in “Hass” avocado fruit were studied during ripening at 20 °C after harvest and after cold storage. Additionally, avocados were treated with 1-MCP to evaluate the delay in softening. Biochemical analysis showed a decrease in galacturonic acid (GalA) in alcohol-insoluble residues (AIR) and water-soluble pectin concomitant to softening, paralleled by an increase in polygalacturonase (PG) activity. In the same way, the β-galactosidase activity increased in soft avocado fruit, along with a reduction in galactose in cell wall material and the Na2CO3-soluble fraction. The arabinose content in the cell wall material did not change during softening. However, there was a change in arabinose ratios between the different fractions of pectin, mainly in the fractions soluble in water and in Na2CO3. The cold storage of avocado fruit did not induce softening of the fruit, but the content of GalA showed a substantial decrease, accompanied by an increase in PG activity. Thus, our work supports the hypothesis that the solubilization of neutral sugars such as arabinose and rhamnose, as well as the loss of galactose content mediated by the enzyme β-galactosidase, were the main factors that began the coordinated action of cell wall remodeling enzymes that resulted in the loss of firmness of avocado fruit.