Eggplant Fruit Research Articles

Proper irrigation amount for eggplant cultivation in a solar greenhouse improved plant growth, fruit quality and yield by influencing the soil microbial community and rhizosphere environment.

Water scarcity is a worldwide problem, and in order to obtain plenty of production, agricultural irrigation water accounts for a large portion. Many studies have shown that the interaction of root microorganisms and soil can promote crop growth. Developing ways to reduce irrigation to maintain soil fertility and ensure crop yield by regulating the root microenvironment is an important research goal. Here, we developed a reasonable irrigation plan for eggplant cultivation in a solar greenhouse. The maximum theoretical amount of water demand during eggplant planting obtained from a previous study was used as the control (CK), and the irrigation in the treatments was reduced by 10, 20 and 30% relative to this amount. The 10% irrigation reduction treatment (T1) significantly improved soil nutrients and increased soil catalase, urease and alkaline phosphatase activities (p < 0.05). Further analysis of rhizosphere microorganisms revealed the highest richness and diversity of the microbial community under the T1 treatment, with Bacilli as the most abundant bacteria and Aspergillaceae as the most abundant fungi and lower relative abundances of Chloroflexi and Acidobacteria (p < 0.05). Changes in microbial community structure under the influence of different irrigation treatments resulted in improvements in rhizosphere N cycling and nutrient catabolism. The plant–microbe interactions led to significant increases in eggplant plant height, root vigour, root surface area, leaf chlorophyll a, leaf net photosynthetic rate, water use efficiency, transpiration rate, and stomatal conductance under the T1 treatment compared to the CK treatment; soluble sugar, soluble protein and free amino acid contents in eggplant fruit increased by 10.8, 12.3 and 6.7%, respectively; and yield increased by 3.9%. Our research proved that the 10% irrigation reduction treatment (T1) could improve microbial community richness and fruit yield, which would improve irrigation efficiency and cost reduction in agriculture.

Effects of Different Rootstocks and Storage Temperatures on Postharvest Quality of Eggplant (Solanum melongena L. cv. Madonna)

In addition to mitigating biotic and abiotic stress, grafting may influence the fruit quality and postharvest quality of eggplants. Few studies have been published on the influence of grafting on the postharvest performance of eggplant fruit. The current work examined the postharvest behavior of grafted and non-grafted eggplant cv. Madonna at 0 and 10 °C storage. Rootstocks include Solanum grandiflorum × Solanum melongena (SH), Solanum torvum (ST), Solanum melongena × Solanum integrifolium (SI), Solanum integrifolium (A), and Solanum lycopersicum cv. Optifort (O) and Emperador (E). The values for soluble solids, L*, and b* of pulp declined throughout storage. The pH of the fruit pulp decreased during storage at 10 °C. The lowest firmness was observed in fruit grafted onto E and O. The oxidation potential (OP) value decreased for fruit harvested from the O rootstock. At 0 °C, the oxidation potential (OP) value increased in fruit harvested from the A rootstock. Fruit firmness reduction at the end of storage in fruit grafted onto SH was less than in the other rootstocks and control plants. Overall, we found that the storage temperature had a more significant effect than the applied rootstock on the studied parameters of the eggplant fruits.

Melatonin alleviates chilling injury and maintains postharvest quality by enhancing antioxidant capacity and inhibiting cell wall degradation in cold-stored eggplant fruit

Melatonin improves the chilling tolerance and quality of postharvest fruit. In this study, we investigated the effect of melatonin on postharvest quality in cold-stored eggplant fruit for 30 d at 5 °C. Melatonin at 100 μmol L−1 was notably effective in decreasing chilling injury (CI) incidence, CI index, weight loss, and in delaying the decrease of lightness, thereby maintaining better postharvest quality of the fruit. Exogenous melatonin inhibited increases in hydrogen peroxide (H2O2), malondialdehyde (MDA), and relative electro-conductivity in the pericarp and pulp, while maintaining higher levels of superoxide dismutase (SOD), catalase (CAT), total polyamines, anthocyanins, and melatonin, as well as the expressions of SOD, CAT1/2, and other genes involved in polyamine biosynthesis (ADC, ODC), melatonin biosynthesis (TDC1, T5H, SNAT1, ASMT, COMT), anthocyanin biosynthesis (PAL, CHS1, CHI, F3H, F3′H, DFR, ANS, 3GT), and cold regulation (COR1, CBF, ZAT2/6/12), thereby conferring the higher chilling tolerance. Melatonin delayed fruit softening and senescence by inhibiting the activities and gene expressions of cell wall degradation enzymes (PME, PG, Cel) and expressions of senescence-associated genes (IAA17, SAG12, SEN4). Overall, these results indicate that melatonin alleviates chilling injury and maintains postharvest quality by enhancing antioxidant capacity and inhibiting cell wall degradation in cold-stored eggplant fruit, which provides a theoretical foundation for extending fruit shelf-life of eggplant during cold storage.

Biochar-Based Fertilizer Enhances the Production Capacity and Economic Benefit of Open-Field Eggplant in the Karst Region of Southwest China

Biochar as an amendment has been widely applied to enhance crop productivity and improve soil quality. However, the effect of biochar-based fertilizer (BF) on the production capacity and economic benefits of open-field eggplant in the karst region remains unclear. A field experiment was carried out in the karst region of Southwest China from 2020 to 2021 to study the ameliorative roles of different application rates (1875, 2250, 2625, and 3000 kg ha−1) of BF on the fresh yield, quality, fertilizer utilization, and economic benefits of fresh eggplant. The results show that BF increased the yield of fresh eggplant by 3.65–13.76% (2020) and 23.40–49.04% (2021) compared to the traditional fertilization practice (TFP). The application of BF reduced the nitrate content and increased the vitamin C (VC) and soluble sugar content of the fruits, which is beneficial for improving the quality of eggplant fruits. Meanwhile, the application of BF not only increased the nutrient uptake of the eggplant but also significantly improved the fertilizer utilization rates, especially the agronomic efficiency (AE) and recovery efficiency (RE). Moreover, BF could also significantly increase the output value and net income of fresh eggplant, which can help farmers increase their income. In conclusion, a BF application rate of 2544–2625 kg ha−1 could be used to improve the yield, fertilizer efficiency, and economic benefits of open-field eggplant and is recommended for managing agricultural production in the karst region of Southwest China.

Sequential application of bio-pesticides suppresses eggplant shoot and fruit borer, Leucinodes orbonalis Guenee infestation

Different bio-pesticides were evaluated against eggplant shoot and fruit borer, Leucinodes orbonalis G. in combination. All combination of bio-pesticides were effective against eggplant shoot and fruit borer but Lycomax + Biotin M + Antario and Lycomax + Biotin M + Fytomax 3% found most potent and control 88.43 and 84.06 percent shoot infestation; 69.67 and 66.44 percent fruit infestation by count; 72.70 and 70.49 percent fruit infestation by weight, respectively. Lycomax + Biotin M + Antario and Lycomax + Fytomax 0.1% + Biomax increased 32.90 and 28.66 percent gross yield; 120.19 and 87.5 percent marketable yield, respectively over control. Individual fruit weight found maximum from Lycomax + Fytomax 0.1% + Biomax and Biotin M + Antario where it was 51.74 g and 48.13 g for marketable fruit while 44.05 g and 44.61 g for infested fruit. The present study revealed that Lycomax + Biotin M + Antario and Lycomax + Biotin M + Fytomax 3% effectively control ESFB while Lycomax + Biotin M + Antario and Lycomax + Fytomax 0.1% + Biomax increases the yield. Therefore, application of Lycomax + Biotin M + Antario might be recommended for successful production of eggplant to get maximum yield with minimum infestation.

AMF and PSB applications modulated the biochemical and mineral content of the eggplants.

This study was conducted to investigate the beneficial role of phosphate solubilizing bacteria (PSB) and arbuscular mycorrhizal fungi (AMF) in improving eggplant fruits' biochemical composition and mineral content. The plants were treated with AMFAcaulospora laevis, and bacteria Pseudomonas fluorescens, and the corresponding variations were measured for mineral content (Ca, Fe, Mg, K, and P), biochemical parameters (dry matter, total soluble solid [TSS], phenolics, chlorogenic acid, vitamin C) along with arbuscular mycorrhizaspore number, and percentage of root colonization. The AMF and PSB-mediated soil and root-associated nutrients become available for uptake via mineralization, solubilization, and mobilization, primarily through the generation of organic acids and P-hydrolysing enzymes by the microbes. All the treatments showed a significant increase in the concentrations of different biochemical components. However, the combination of both A. laevis and P. fluorescens was found to be the most efficient. These results indicated the possibility of A. laevis and P. fluorescens being used as biofertilizers.

Comparative Transcriptome Analysis Reveals Gene Expression Differences in Eggplant (Solanum melongena L.) Fruits with Different Brightness.

Fruit brightness is an important quality trait that affects the market value of eggplant. However, few studies have been conducted on eggplant brightness. In this study, we aimed to identify genes related to this trait in three varieties of eggplant with different fruit brightness between 14 and 22 days after pollination. Using RNA-Seq Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses, we found that wax- and cutin-related pathways and differentially expressed genes displayed significant differences among different development stages and varieties. Scanning electron microscopy revealed that the wax layer was thinner in ‘30-1’ and ‘QPCQ’ than in ‘22-1’. Gas chromatography-mass spectrometry analysis revealed that wax content was significantly lower in ‘30-1’ than in ‘22-1’, which indicated that wax may be an important factor determining fruit brightness. We further identified and analyzed the KCS gene family, which encodes the rate-limiting enzyme of FA elongation in wax synthesis. The results provide an insight into the molecular mechanisms of fruit brightness in eggplants and further eggplant breeding programs.

Exogenous melatonin improves the chilling tolerance and preharvest fruit shelf life in eggplant by affecting ROS- and senescence-related processes

Low temperature is the most common abiotic stress factors during the eggplant cultivation in solar greenhouses. Melatonin plays important roles in plant resistance to low temperature. However, the role of melatonin in regulating chilling tolerance and extending the preharvest shelf life of eggplant fruits is still unknown. In this study, we investigated the effects of exogenous melatonin on eggplant plants and fruits in response to low temperature. Under simulated low-temperature conditions, exogenous melatonin significantly relieved the chilling symptoms of seedlings by reducing reactive oxygen species (ROS) and malondialdehyde (MDA) levels and relative leakage rates. These reductions were caused by higher superoxide dismutase (SOD) and catalase (CAT) activities and increased endogenous polyamine and melatonin levels compared with those in untreated seedlings. Notably, the expression levels of SOD, CAT1/2, and polyamine synthesis genes (ADC and ODC) were also increased by 100 μmol · L−1 melatonin, as well as those of genes involved in melatonin synthesis (TDC, T5H, SNAT, ASMT, and COMT) and cold regulation (COR1, CBFa/b, and ZAT2/6/12). To further investigate the effects of melatonin on eggplant leaves and fruits under natural low temperature conditions, 100 μmol · L−1 melatonin was sprayed on the functional leaves at three days before commodity maturation. Melatonin significantly alleviated chilling injury in the leaves and pericarp and extended the preharvest shelf life of the fruit by increasing the expression of COR1, CBF, ZAT2/6/12, and API5 and decreasing the expression of senescence-related genes (NCED1/2 and SAG12). Therefore, 100 μmol · L−1 melatonin improved chilling tolerance and fruit shelf life by upregulating ZAT2/6/12 to affect ROS- and senescence-related processes, which provides a reference for alleviating cold stress and extending the preharvest fruit shelf life in eggplant.

Determining the Effects of Light on the Fruit Peel Quality of Photosensitive and Nonphotosensitive Eggplant.

With the development of facility agriculture, low-light stress is a prominent problem and a popular research topic currently. In this study, transcriptome analysis was used to analyze the genes in the fruit peel of photosensitive and nonphotosensitive eggplant and to explore the mechanism of changes in fruit color, texture, hormone content, aroma, and taste of these two different types of eggplant. We identified 51, 65, 66, and 66 genes involved in synthesizing anthocyanins, texture, hormone content, and aroma and flavor, respectively, in the two different types of eggplant based on the variation in gene expression trends in the fruit peel. These results provide a basis for further analysis of the molecular mechanism underlying the regulatory processes in eggplant fruits under low-light stress.

First report of Anthracnose on 'Purple Dream' Solanum melongena in Malaysia Caused by Colletotrichum siamense.

'Purple Dream' eggplant (Solanum melongena) is widely grown for its edible fruits in Malaysia. In July 2021, anthracnose symptoms were observed on fruit with a disease severity of approximately 80% and an incidence of 10% in a field (14.6 m2) (5°56'50.9"N, 116°04'31.9"E) located in the Penampang district of Sabah province. The symptoms initially appeared as irregular light brown spots. As the disease progressed, the spots enlarged and merged into extensive lesion patches that appeared in concentric circles. The symptomatic fruit tissues (5 x 5 mm) were surface sterilized based on Khoo et al. (2022), and plated onto potato dextrose agar (PDA), and incubated at 25°C in the dark. Colonies with gray-white fluffy mycelia developed after 7 days, and the reverse of the colonies was dark brown. A representative isolate named Penampang was characterized morphologically and molecularly. The conidia were one-celled, cylindrical, blunt at the ends, hyaline, smooth, and measured 13.3 to 16.1 x 3.9 to 6.0 µm (n= 20). Appressoria ranged in size from 7.6 to 9.3 m x 5.5 to 6.6 µm (n= 20) and were spherical to irregular in shape and dark brown in colour. Genomic DNA was extracted from fresh mycelia of isolate Penampang based on Khoo et al. (2021) and Khoo et al. (2022). ITS1/ITS4, CL1C/CL2C, ACT-512F/ACT-783R, CHS-79F/CHS-354R, and GDF1/GDR1 primer pairs were used to amplify the isolate's internal transcribed spacer region (ITS), and partial calmodulin (CAL), actin (ACT), chitin synthase (CHS-1), and glyceraldehyde-3-phosphate dehydrogenase genes (GAPDH) (Weir et al. 2012). PCR products were sequenced by Apical Scientific Sdn. Bhd. (Selangor, Malaysia). Sequences were deposited in GenBank under the accession numbers OL957466 (ITS), OL953035 (CAL), OL953032 (ACT), OL953038 (CHS-1), and OL953041 (GAPDH). They were 99% to 100% identical to the Colletotrichum ti ITS (NR_120143) (515 bp out of 519 bp), and C. siamense CAL (JX009714) (729 bp out of 731 bp), ACT (JX009518) (282 bp out of 282 bp), CHS-1 (JX009865) (299 bp out of 299 bp), and GAPDH (JX009924) (276 bp out of 277 bp) sequences. ITS sequences do not reliably resolve relationships within the C. gloeosporioides complex (Weir et al. 2012). The phylogenetic maximum likelihood analysis using the combined ITS, CAL, ACT, CHS-1, and GAPDH sequences indicated that the isolate was part of the C. siamense clade (100% bootstrap value) that also contained the type isolate ICMP 18578 of this species. Morphological and molecular characterization matched the description of C. siamense (Huang et al. 2021; Ismail et al. 2021). Koch's postulates were performed similarly as described by Chai et al. (2017) but using spray-inoculation (108 spores/ml) of three healthy 'Purple Dream' eggplant fruit with isolate Penampang. Water was sprayed on three additional fruits that served as controls. All the fruits were incubated at 25°C and less than 90% relative humidity. Symptoms similar to those observed in the field developed 5 days after inoculation. No symptoms occurred on controls. The experiment was repeated two more times. The reisolated fungi were identical to the pathogen morphologically and molecularly. To our knowledge, this is the first report of C. siamense causing anthracnose on fruit of 'Purple Dream' S. melongena in Malaysia as well as worldwide. Our findings expand the host range of C. siamense and indicate that the pathogen could potentially limit 'Purple Dream' eggplant production in Malaysia.

Genetic mapping of simply inherited categorical traits, including anthocyanin accumulation profiles and fruit appearance, in eggplant (Solanum melongena).

The appearance quality of the eggplant (Solanum melongena L.) fruit is an important trait that influences its commercial value. It is known that quality traits such as anthocyanin composition and fruit surface pattern are categorical and are inherited simply. However, research examples of gene mapping for the composition (anthocyanin accumulation profile) and the surface pattern in eggplant fruit are limited. To map loci for these traits including the accumulation profiles of two anthocyanins, a widely spreading anthocyanin, delphinidin 3-(p-coumaroyl) rutinoside-5-glucoside (nasunin), and the relatively rare delphinidin 3-glucoside (D3G), we used two F2 intracrossed populations (LWF2 and N28F2). For the LWF2 population, mapping was achieved by reconstructing the linkage map created by Fukuoka et al. [1]. In the case of the N28F2 population, we constructed a linkage map consisting of 13 linkage groups using 238 simple sequence repeats, 75 single-nucleotide polymorphisms. Using the two F2 populations, the nasunin accumulating profile, the striped pattern on the fruit surface, the colors of flowers, fruit, and calyxes, and the D3G accumulating profile were genetically mapped. Furthermore, by utilizing the eggplant reference genome information, mutations in the causative candidate genes for those loci were identified. Overall, the results of this study suggest that inactivation of key enzymes of anthocyanin metabolism and the gene orthologous to the tomato u gene are potential causes of observed variety in eggplant appearance traits.

In Vitro Screening and Field Performance of EMS-Treated Eggplants for the Selection of Shoot and Fruit Borer-Resistant Plants

The shoot and fruit borer has asserted itself as a severe pest of eggplant. In vitro mutagenesis is an excellent method for producing mutants resistant to biotic and abiotic stresses. This study aimed to create eggplant mutants that were resistant to shoot and fruit borer infestation. In the Murashige and Skoog (MS) medium, two genotypes, including a landrace, were treated with varying amounts of EMS. Among the treatments, MS medium supplemented with 2% EMS demonstrated the most favorable effect. Explant performance dropped by up to 1.5% with an increase in EMS in the medium. The 2% EMS dose was appropriate for in vitro mutant eggplant development, but the higher dose was extremely damaging. EMS made several mutants sterile. Three landrace mutants were insect-resistant. Total phenols, leaf chlorophylls A and B, antioxidants, and solasodine were abundant in these genotypes. Correlation studies found a link between affected fruits and shoots and total phenols, antioxidants, and solasodine. Solasodine was shown to be related to chlorophylls A and B. The eggplant shoot and fruit borer infestation rate can be reduced by increasing these specific biochemical properties.

Effect of Soil Regenerative Practice on Selected Soil Physical Properties and Eggplant (Solanum melongena L.) Yield

Living mulches can play a crucial role in the protection of the soil against erosion, as well as biological and chemical degradation. Soil fertility and its physical properties, including soil structure, are of special importance to crops. Soil physical properties are affected, among other factors, by the type of tillage. In order to determine the effect of regenerative practice (living mulches) on soil physical properties, a two-factorial experiment was conducted. The first factor involved white clover and perennial ryegrass as an intercropping of eggplant. The second factor was the living mulches sowing term: three weeks before eggplant planting, at the time of planting and three weeks after eggplant planting. Covering eggplant inter-rows with living mulches reduced eggplant yield and was beneficial to soil structure and improved water resistance of soil aggregates. Perennial ryegrass had a slightly more advantageous effect on yield and improvement of soil physical properties, as compared to white clover. The greater eggplant fruit yield was obtained from vegetable grown without companion plants. The application of living mulches (especially Trifolium repens L.) caused a non-significant decrease in eggplant fruit yield. It was found that limiting the growth of seedlings sown on the first date result in a decrease in marketable fruit yield (on average 14%). A similar result occurred when living mulches were sown on the planting date of eggplants and difference between the yields was 4.3%. The first term of sowing living mulches—three weeks before eggplant planting—no significantly affected the mean weighted diameter of soil aggregate (MWDg), the water stability index (ΔMWD), the index of waterproof index (Wod) and the soil structure index (W). Later sowing terms resulted in the improvement of the majority of the parameters; however, this was not confirmed statistically. Soil with periodic mechanical treatment of inter-rows showed the 3–4% lower values of soil porosity, 3–16% increased compactness, as well as 28–30% lower indices soil structure and 28–30% for water resistance of soil aggregates compared to the living mulches system.

Effects of hot water treatment to alleviate chilling injury and enhance phenolic metabolism in eggplant fruit during low temperature storage

Eggplant (Solanum melongena L.) fruit is highly perishable vegetable due to rapid quality deterioration when stored under ambient temperature. The current handling and storage temperatures, below optimum storage temperature (<10°C), extend the storage life, but chilling injury (CI) occurs after a longer storage. In this study, the effects of pre-storage hot water dipping at 45°C hot water for 10 min on alleviation of CI and enhancement of phenolic metabolism in cold stored eggplant fruit for 15 d were investigated. Fruit stored at 10°C showed no CI and maintained fruit quality, while non-treated fruits stored at 1°C indicated severe CI. Hot water treatment alleviated CI incidence and inhibited the increases in malondialdehyde and hydrogen peroxide levels, and enhanced phenolic metabolism by increases of total phenolic levels and phenylalanine ammonia-lyase activities compared with the non-treated fruits during storage at 1°C. These results indicate that the alleviation of CI in eggplant fruit by hot water treatment at 45°C for 10 min might be due to the increase of antioxidant activity by enhancement in phenolic metabolism.

An evaluation of African eggplant fruits engineering properties in relation to robotic harvesting

The construction and application of eggplant harvesting robot required some basic physical characteristics and mechanical properties of the eggplant fruit. The physical characteristics (geometric mean diameter, surface area, volume, sphericity, and weight), and mechanical properties (failure energy, failure force, deformation, shear resistance, and shear force) of the Africa beauty eggplant fruits, were evaluated at three different maturity stages in this study. The maturity stages adopted in this study were 21 days after peak anthesis (DAPA), 28 DAPA, and 35 DAPA. The results obtained showed that the maturity stage resulted in a significant effect (p&lt;0.05) on the mechanical properties of the eggplant fruits. The geometric mean diameter, surface area, volume, sphericity, and weight of the fruits significantly increased as the fruits matured from 21 DAPA to 35 DAPA (p&lt;0.05). The failure energy, failure force, shear resistance, and shear force of the fruits were fluctuating during maturity; fruits harvested at 21 DAPA recorded the lowest values, while those harvested at 28 DAPA recorded the highest values. In addition, the study revealed that the loading position had a significant effect on the mechanical properties of the fruits (p&lt;0.05). The best eggplant harvesting robot properties obtained in this study was at 28 days after peak anthesis (DAPA). The physical characteristics and mechanical properties results of eggplant fruit, obtained in this study will be useful information for the application in the design and construction of eggplant fruits robot harvesting.

STUDYING THE CHEMICAL COMPOSITION OF THE RESIDUES OF SOME PLANT SOURES AND IDENTIFY THE CONTENT OF PHENOLIC COMPOUNDS

This study was conducted in the laboratories of the College of the Agriculture / University of Tikrit and the College of the Science / University of Anbar during the period from 1/11/2020 to 1/9/2021 the aim is to study the chemical composition of the peels of some different fruits of plants, which were (eggplant, watermelon, pumpkin, orange, pomelo, and pomegranate). Fruits The results of the chemical composition of the peels of the fruits used showed the percentage of moisture, ash, fat, fiber, protein, and carbohydrates reached 7.14, 5.9, 2.56, 14.91, 11.43, 59.06% 10.29, 11.2, 3.08, 29.87, 11.81, 33.33%, 6.89, 6.7, 5.40, 15.60, 8.48, 56.93%, 11.23, 5.15, 10.62, 13.41, 5.74, 52.85% 9.19, 6.7, 5.99, 15.40, 8.48, 54.24% 10.56, 2.2, 1.89, 15.87, 4.37, 65.11%, the peels of eggplant, watermelon, pumpkin, orange, pomelo and pomegranate fruits respectively. The content of the phenols in the peels of the fruits under study showed the presence of several types, with the peels of pumpkin, pomegranate, eggplant and pomelo distinguished by a high content of gallic acid, with percentages 40.697, 39.117, 36.519, 32.748%, respectively, followed by Apigenin, as pumpkin peels were characterized by the highest content It reached 23.179 %, compared with pomegranate 21.009%, eggplant 19.554%, watermelon 16.078%, pumpkin 15.380%, and orange 2.433%. The lowest was Catching, with percentages 6.133, 0.083,9.003, and 0.737,5.183 and 6.664% for the peels eggplant, watermelon, pumpkin, orange, pomelo, and pomegranate fruits, respectively, and the rest of the types of phenols range between these percentages.

Integrating Transcriptomic and Metabolomic Analyses to Explore the Effect of Color Under Fruit Calyx on That of Fruit Apex in Eggplant (Solanum melongena L.).

Fruit color is an important commercial characteristic of eggplant (Solanum melongena L.), which affects both the profits of growers and consumer choice. Two eggplant inbred lines were discovered: “Z,” which is a light purple color under the fruit calyx, with purple on the fruit apex; and “L,” fruits of which are green under the calyx and at the apex. To determine the molecular mechanisms underlying the effect of fruit peel color under the calyx on that at the fruit apex, we conducted a combined transcriptomic and metabolomic analyses of the Z and L inbred eggplant lines. Transcriptome analysis of peel samples from three fruit regions (under the calyx, the apex, and the middle surface) of each line was conducted by RNA sequencing, and generated a total of 791,512,404 clean reads from 18 samples (three biological replicates). Differentially expressed genes (DEGs; n = 424) were identified in comparisons of peel samples from the three sites of L line fruits. Gene ontology analysis showed that “catalytic activity” was extremely significantly enriched. Further, DEGs (n = 8) were enriched in the Kyoto Encyclopedia of Genes and Genomes pathway “flavonoid biosynthesis.” Levels of CHI, LDOX, F3′5′H, and dihydroflavonol reductase were higher in the Z line than the L line. In addition, metabolome analysis showed that, 10 differentially accumulated metabolites were detected between peel samples from the apex of L and Z line fruit. The most significant DAM was delphinidin-3-O-rutinoside (Z line content, 34.89 μg/g vs. L line content 0.01 μg/g). Combined transcriptomic and metabolomic analyses indicated that DFR and F3′5′H were closely related to content of the metabolites, cyanidin and delphinidin, and that some downstream metabolites differed significantly between the L and Z lines. Content levels of delphinidin-3-O-rutinoside, delphinidin-3-O-glucoside, cyanidin-3-O-glucoside, and cyanidin-3-O-rutinoside were markedly down-regulated in the L line. Altogether, increased CHI levels could up-regulate the downstream genes, LDOX, F3′5′H, and DFR, which further lead to increasing the content of delphindin. Thus, the uniform purple color was presented at the apex of fruits in Z plants. These findings not only identify key candidate genes, but will also improve understanding of the genetics and the efficiency of breeding for eggplant fruit color.

Delphinidins and Naringenin Chalcone Underlying the Fruit Color Changes during Maturity Stages in Eggplant

Purple eggplant fruits often turn brown during maturity stages, severely influencing their market value and shelf life. However, the metabolites and genes accounting for the fruit color changes are largely unknown. Here, metabolites and gene expression analyses were used to explore the candidates underlying the differences in fruit color changes between two eggplant genotypes, ‘14-345’ and ‘CGN23829’, with contrasting fruit color changes during fruit development. We found that flavonoids are the most differentially accumulated metabolites between ‘14-345’ and ‘CGN23829’. Higher contents of D3R and D3G are important for keeping the purple color at the maturity stage. Naringenin chalcone likely accounts for the color changes from purple to brown in ‘14-345’. Notably, at the physiological maturity stage, lower expression of early biosynthetic genes (EBGs) involved in the flavonoid biosynthesis pathway is important to keep lower contents of metabolites upstream of anthocyanins, thus leading to more purple coloring. Taken together, the results indicate that delphinidins and naringenin chalcone play important roles in determining eggplant fruit color changes at maturity stages, which is helpful for further dissecting the mechanisms underlying fruit color differences and changes in eggplants.

Metabolomic Analysis, Combined with Enzymatic and Transcriptome Assays, to Reveal the Browning Resistance Mechanism of Fresh-Cut Eggplant.

Browning has been the primary limitation in eggplant processing. This study investigates the molecular mechanism underlying fresh-cut eggplant fruit browning by observing the physicochemical characteristics of browning-resistant (‘F’) and browning-sensitive (‘36′) eggplant cultivars. Browning-related enzyme activity and gene expression (PPO, LOX, and PLD) were significantly higher in the ‘36′ eggplant, thereby enhancing the degree of browning, compared to the ‘F’ eggplant. The MDA content and O2− production rate progressively increased as browning increased, while the antioxidant capacity of the fruit decreased. The cutting injury significantly activated the expression of PAL, thereby inducing the accumulation of phenolic acids, while the PPO gene was significantly upregulated, which activated the activity of polyphenol oxidase. Our results showed that the oxidation of chlorogenic acids to chlorogenic quinones resulted in the occurrence of browning, which suggests chlorogenic acid as the main browning substrate in fresh-cut eggplant.

A novel cover material improves cooling energy and fertigation efficiency for glasshouse eggplant production

Glasshouses hold the potential to improve global food security, but high energy costs are an ongoing challenge in bringing them to the forefront of agriculture in warm climates. Here, the energy-saving potential of a ‘Smart Glass’ (SG), diffuse glass fitted with ULR-80 film which permits transmission of 85% of photosynthetically-active light and blocks heat-generating radiation, was characterised for a warm-climate glasshouse. Two consecutive 6-month trials of eggplant crops were grown in a high-tech glasshouse to compare SG to standard diffuse glass (control) in both cool and warm climate conditions. The SG reduced cooling energy use by 4.4% and fertigation demand by 29% in cooler months, and reduced cooling energy use by 4.4% and fertigation demand by 18% in warmer months. The SG did not significantly affect ventilation or heating energy use, but substantially reduced fruit yield. SG may be beneficial for reducing nutrient/water use alongside minor energy savings in commercial glasshouses. However, re-engineering the spectral characteristics of SG could improve eggplant fruit yield while maintaining reductions in energy, nutrient, and water use in the glasshouse.