Location: Food Quality Laboratory
2023 Annual Report
Objectives
Objective 1: Identify, characterize and manipulate key regulatory genes for antioxidant biosynthesis in pre- and post- harvest produce to optimize product quality and nutritive value. [NP 306, C1, PS1A]
Sub-objective 1A: Analyze global gene expression profiles in response to treatments and identify candidate genes and signaling pathways that regulate fruit ripening and biosynthesis of sugars, acids and phenylpropanoids.
Sub-objective 1B: Produce transgenic plants/fruits with increased or reduced expression of selected candidate genes, and determine their functional significance in fruit ripening and nutritive quality.
Objective 2: Identify pre-harvest parameters and develop commercially relevant treatments that enhance microgreen productivity, quality and nutritive value for urban and space farming. [NP 306, C1, PS1B]
Sub-objective 2A: Evaluate the effect of preharvest treatments on microgreen productivity, quality and nutritive value in controlled environment settings.
Sub-objective 2B: Conduct global gene expression analysis of microgreens in response to abiotic stresses encountered in space or under microgravity.
Approach
For first objective, strawberry fruit at early and late stage of fruit development will be treated with BZT and AMD, two compounds showing impact in controlling fruit color and firmness, etc. Global gene expression will be studied to identify candidate genes related to fruit ripening and biosynthesis of sugars, acids and phenylpropanoids. Selected genes can be used as functional markers for industry management and breeders. Once these genes are identified, the already commercially available treatments, such as calcium and UVB, will be applied to determine whether and how these treatments affect expression of the selected genes. The optimum treatments will be identified from two approaches and/or combination of two approaches if there is an additive or synergistic effect. Further, stable or transient transformation with silencing or over-expression gene constructs will be used to assess the function of specific genes in various aspects of fruit physiology and metabolism, including ripening, sensory parameters, responses to stresses, and accumulation and/or retention of health-beneficial secondary metabolites.
For second objective, microgreens, young vegetable seedlings with rich nutrition, such as broccoli, red radish, amaranth and pea will be selected for this study. The seeds of microgreens will be subjected by physical treatments, such as cold plasma, UVC to control pathogen infection and promote seed germination. Seedlings will be treated with different lights, UVB, and calcium and carbon dioxide. Microgreen growth and quality at the production level will be evaluated to determine the best practice for microgreen yield and quality. In collaboration with NASA, microgreen growth and quality will be studied under microgravity and high carbon dioxide. Global gene expression analysis of microgreen responses to stress both in controlled environment systems on earth and in microgravity will be investigated to determine how stress relates to yield and quality at the gene and metabolic pathway level. Putative differentially expressed genes will be used to find which genes are the better markers for future use in industry.
Progress Report
This is the third-year report for Project Number 8042-43000-016-000D “Integrated Approaches to Improve Fruit and Vegetable Nutritional Quality with Improved Phenolics Contents” under National Program 306 “Product Quality and New Uses”, Component 1, Foods. Objective 1 is to identify, characterize and manipulate key regulatory genes for antioxidant biosynthesis in pre- and post- harvest produce to optimize product quality and nutritive value. Objective 2 focuses on identification of pre-harvest parameters and develop commercially relevant treatments that enhance microgreen productivity, quality, and nutritive value for urban and space farming. Progress was made in both objectives and their subobjectives.
For Objective 1, previously two types of putative plant growth regulators, carboxamide (CAD) and phenylacetamide (PAD) analogs was identified to show effective to promote and inhibit fruit development and ripening in strawberry and tomato, respectively. Based on transcriptome analyses, twenty genes related to fruit development and ripening were selected as possible functional markers for breading. Of them, three genes were selected for functional/transgenic study. The constructs of overexpressing and knockout were made. Transient transformation in strawberry fruit showed that overexpressing or knocking down all three genes had clear impact on delaying or accelerating fruit ripening. Stable transformation was carried out, and heterozygous transformants have been obtained. Analysis of plant growth and fruit development are on the way. Furthermore, last year CAD and PAD were used to test the effectiveness on potato sprouting, and the results were not clear-cut because the chemical delivery/spray was not effective. This year, the delivery approach was improved, and gaseous CAD inhibited potato sprouting as effective as CIPC, a most popular sprouting inhibitor in market. Both CAD and PAD have been filed for USA patent application because of their great potential to be used by growers and industry to control fruit quality and shelf life and reduce food waste. A new invention disclosure for CAD as a novel potato sprouting inhibitor is planned to file.
Objective 2, previously cold plasma was shown to increase sprout and microgreen yield and nutritional quality. This year the effectiveness of cold plasma and ozone on reducing seed borne pathogens and human pathogen was studies. Cold plasma and ozone combinations can reduce the pathogens significantly. To reduce the energy cost for indoor faming, low light intensity effect on microgreen growth was studied. It is found that low light intensity plus far-red light remarkably increased microgreen yield. These results will contribute to controlled environment agriculture.
Calcium deficiency caused bone loss is a big challenge for astronauts. In collaboration with NASA, previously it had been found that simulated microgravity could increase broccoli microgreen yield and calcium content. In this year, the bioinformatic analysis of the data has been carried out, and the candidate genes affected by gravity and calcium were founded. The overall impact of this research is to provide astronauts and people in space new information for high yield and calcium content microgreens.
Accomplishments
1. Preharvest UV-B treatment improves strawberry quality and extends shelf life. Postharvest ultraviolet B (UV-B) radiation has been used to control pathogen incidence on fresh produce, but little attention has been paid to preharvest UV-B effect on strawberry fruit quality and storage. In this study, ARS researchers in Beltsville, Maryland, treated strawberry plants grown in greenhouse were irradiated with UV-B lamps with low intensity (0.7362 J/s m2) for 1 and 2 h every day after flowering. The preharvest UV-B-treated fruits had lighter color than the control. Total soluble solids, total phenolics content and total anthocyanin content of UV-B-treated fruits were higher than for the control fruits. Further evaluation of the fruit quality during cold storage show that UV-B-treated fruits maintained better appearance and quality, and reduced fruit decay. Examination of expression of genes related to UV-B signaling indicated that HY5 was the major component of UV-B signaling during the green and white stages. However, anthocyanin genes were highly responsive to UV-B treatment during the red stage. These results suggest that utilization of a low dose of UV-B radiation during the growth stage can improve strawberry fruit quality and extend shelf life. This research facilitates the utilization of preharvest UV-B treatment for improving fruit quality in controlled environment agriculture.
2. Utilization of freeze-thaw to change isoflavone composition of germinated soybeans. Aglycones are isoflavone monomers with a high biological activity after dietary intake. ARS researchers in Beltsville, Maryland, investigated the effect of freeze-thaw on isoflavone composition in germinated soybeans, particularly the conversion of aglycones. The germinated soybeans were frozen at -20 °C, -80 °C, and - 196 °C and subsequently thawed at 4 °C, 10 °C, and 25 °C. Results showed aglycones content increased most at -20 °C. The effect of thaw temperature and time indicated there were approximately 89% glucosides forms converted to aglycones during freeze-thaw. These results indicated that freeze-thaw greatly changed the content and profile of isoflavones, resulting in a sharp increase in the content of aglycones, and provided an effective approach for industry to enrich aglycones of germinating soybeans.
Review Publications
Ji, W., Yang, T., Song, Q., Ma, M. 2022. Isoflavone composition of germinated soybeans after freeze-thaw. Food Research International. 16. Article 100493. https://doi.org/10.1016/j.fochx.2022.100493.
Zhu, X., Trouth, F.J., Yang, T. 2023. Preharvest UV-B treatment improves strawberry quality and shelf-life. Horticulturae. 9(2):211. https://doi.org/10.3390/horticulturae9020211.
Zhang, M., Ma, M., Yang, T., Li, M., Sun, Q. 2022. Delineating the dynamic transformation of gluten morphological distribution, structure, and aggregation behavior in noodle dough induced by mixing and resting. Food Chemistry. 386:132853. https://doi.org/10.1016/j.foodchem.2022.132853.
