Freezing effect on some quality parameters of transgenic parthenocarpic eggplants

Seedlessness Trait and Genome Editing—A Review

Parthenocarpy and stenospermocarpy are the two mechanisms underlying the seedless fruit set program. Seedless fruit occurs naturally and can be produced using hormone application, crossbreeding, or ploidy breeding. However, the two types of breeding are time-consuming and sometimes ineffective due to interspecies hybridization barriers or the absence of appropriate parental genotypes to use in the breeding process. The genetic engineering approach provides a better prospect, which can be explored based on an understanding of the genetic causes underlying the seedlessness trait. For instance, CRISPR/Cas is a comprehensive and precise technology. The prerequisite for using the strategy to induce seedlessness is identifying the crucial master gene or transcription factor liable for seed formation/development. In this review, we primarily explored the seedlessness mechanisms and identified the potential candidate genes underlying seed development. We also discussed the CRISPR/Cas-mediated genome editing approaches and their improvements.

Nutritional value and antioxidant content of seed-containing and seedless eggplant fruits of two cultivars grown under protected cultivation during autumn-winter and spring-summer

BACKGROUND

Due to their low carbohydrate and high antioxidant content, eggplants are beneficial for the human diet. At <15 °C, pollen production and fertility are reduced and plant-growth regulators may be used to set seedless fruit. Because only the agronomic effects of hormone are well-documented, we investigated the composition and metabolism during the development/maturation of seed-containing and seedless fruits of two cultivars grown over two seasons.

RESULTS

The respiration rate of both seedless and seed-containing fruit decreased with development and maturation. In seedless fruit, starch content decreased at market maturity, whereas in seed-containing fruit starch increased. Respiration and starch were higher in spring-summer than in autumn-winter. Disaccharides were highest at market maturity, with sucrose generally higher in seed-containing fruit; monosaccharides were variable and protein content was reduced in seedless fruit. Phenols closely correlated with antioxidant activity and decreased with development; at market maturity in spring-summer phenols were higher in seedless fruit (Tsakoniki) or unaffected (Emi). Polyphenol oxidase and peroxidase activities were mostly higher in seed-containing fruit, but browning was higher in seedless fruit.

CONCLUSIONS

Notwithstanding reduced protein and increased browning, seedless fruit at market maturity presented less starch, hence fewer calories, and more antioxidants (phenols) for the human diet than the corresponding seed-containing fruit. © 2017 Society of Chemical Industry.

Heterologous expression of Arabidopsis C-repeat binding factor 3 (AtCBF3) and cold-regulated 15A (AtCOR15A) enhanced chilling tolerance in transgenic eggplant (Solanum melongena L.)

Our study shows that the expression of AtCBF3 and AtCOR15A improved the chilling tolerance in transgenic eggplant. In an attempt to improve chilling tolerance of eggplant (Solanum melongena L) plants, Arabidopsis C-repeat binding factor 3 (AtCBF3) and cold-regulated 15A (AtCOR15A) genes both driven by an Arabidopsis RESPONSIVE TO DESSICATION 29A promoter (AtRD29A) were transferred into the plants of eggplant cultivar Sanyueqie. Two independent homozygous transgenic lines were tested for their cold tolerance. The leaves of the transgenic plants in both lines withered much slower and slighter than the wild-type plants after exposure to cold stress treatment at 2 ± 1 °C. The gene expression of AtCBF3 and AtCOR15A was significantly increased as well as the proline content and the levels of catalase and peroxidase activities, while the relative electrical conductivity and the malondialdehyde content were remarkably decreased in the transgenic plants compared with the wild type at 4 ± 0.5 °C. The results showed that the expression of the exogenous AtCBF3 and AtCOR15A could promote the cold adaptation process to protect eggplant plants from chilling stress.

Diversity and relationships in key traits for functional and apparent quality in a collection of eggplant: fruit phenolics content, antioxidant activity, polyphenol oxidase activity, and browning

Eggplant (Solanum melongena) varieties with increased levels of phenolics in the fruit present enhanced functional quality, but may display greater fruit flesh browning. We evaluated 18 eggplant accessions for fruit total phenolics content, chlorogenic acid content, DPPH scavenging activity, polyphenol oxidase (PPO) activity, liquid extract browning, and fruit flesh browning. For all the traits we found a high diversity, with differences among accessions of up to 3.36-fold for fruit flesh browning. Variation in total content in phenolics and in chlorogenic acid content accounted only for 18.9% and 6.0% in the variation in fruit flesh browning, and PPO activity was not significantly correlated with fruit flesh browning. Liquid extract browning was highly correlated with chlorogenic acid content (r = 0.852). Principal components analysis (PCA) identified four groups of accessions with different profiles for the traits studied. Results suggest that it is possible to develop new eggplant varieties with improved functional and apparent quality.

Seedless fruit production by hormonal regulation of fruit set

Seed and fruit development are intimately related processes controlled by internal signals and environmental cues. The absence of seeds is usually appreciated by consumers and producers because it increases fruit quality and fruit shelf-life. One method to produce seedless fruit is to develop plants able to produce fruits independently from pollination and fertilization of the ovules. The onset of fruit growth is under the control of phytohormones. Recent genomic studies have greatly contributed to elucidate the role of phytohormones in regulating fruit initiation, providing at the same time genetic methods for introducing seedlessness in horticultural plants.