Transcriptomics and Metabolomics Reveal the Possible Mechanism by which 1-MCP Regulates the Postharvest Senescence of Zizania latifolia

To understand the mechanism governing the postharvest senescence of Zizania latifolia, and the regulatory mechanism induced by 1-methylcyclopropene (1-MCP) during storage at 25°C, physiobiochemical and conjoint analyses of the transcriptome and metabolome were performed. The results indicated that 1-MCP treatment engendered changes in the expression of genes and metabolites during the postharvest storage of Z. latifolia. The 1-MCP treatment maintained a good visual appearance, preserved the cell structure, and membrane integrity of Z. latifolia by keeping the expression of membranes-related lipolytic enzymes (and related genes) low and the amount of phosphatidylethanolamine high. Compared to the control group, 1-MCP treatment enhanced the activities of antioxidant enzymes, resulting in a decrease of reactive oxygen species (ROS) and malondialdehyde (MDA) contents, and thus inhibition of oxidative damage and loss of membrane integrity. In addition, 1-MCP treatment retarded the senescence of Z. latifolia by down-regulating the expression of ethylene biosynthesis-related genes and promoting up-regulation of brassinosteroid insensitive 1 (BRI1) kinase inhibitor 1, calmodulin (CaM), glutathione reductase, jasmonate amino acid synthase, and mitogen-activated protein kinase (MAPK)-related genes. Moreover, 1-MCP retarded Z. latifolia senescence by inducing the activity of ATP-biosynthesis related genes and metabolites. Our findings should facilitate future research on the postharvest storage of Z. latifolia, and could help delay senescence and prolong the storage time for commercial applications.

Polyamines accentuate vase life by augmenting antioxidant system in cut spikes of Consolida ajacis (L.) Schur.

Postharvest senescence is one of the crucial challenges limiting the marketability of cut flowers. Pertinently, recent investigations implicate extensive role of polyamines in regulation of flower senescence. The present study was envisaged to test the efficacy of poylamines in preserving the postharvest quality of Consolida ajacis (C. ajacis) cut spikes. The cut spikes of C. ajacis were subjected to various treatments of polyamines viz, 4 mM Spermine (SPM), 6mM Putrescine (PUT) and 6 mM Spermidine (SPD). A separate set of spikes held in distilled water represented the control. Our results authenticate a significant improvement in vase life of cut spikes of C. ajacis as compared to control. The increment in vase life was commensurate with the higher concentration of sugars, proteins and phenols in the tepal tissues. Polyamines amplified the activity of various antioxidant enzymes viz, superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX) to overcome the deleterious effects of reactive oxygen species (ROS). The membrane outflow of tepal tissues was profoundly reduced due to attenuated lipoxygenase (LOX) activity. These findings reveal conspicuous role of polyamines particularly SPM in modulation of flower senescence in cut spikes of C. ajacis.

The Antioxidant Defense System during Lanzhou Lily Scales Storage Is Modulated by Hydrogen Sulfide

As an important gaseous regulator, hydrogen sulfide (H2S) is involved in various aspects of plant processes, including seed germination, stomatal movement, and postharvest senescence. The preservation capacity of Lanzhou lily (Lilium davidii var. unicolor Salisb) scales fumigated with or without exogenously applied sodium hydrosulfide (NaHS, a H2S donor) was investigated in the current study. Results indicate that NaHS fumigation was able to extend storage life and elicit endogenous H2S production of postharvest Lanzhou lily scales with an optimal concentration at 0.8 mM. Moreover, exogenously applied NaHS (0.8 mM) led to higher soluble sugar, soluble protein, and ascorbic acid levels and lower total phenolic and flavonoid contents compared with those of the control. The application of 0.8 mM NaHS also reduced the lipid peroxidation level and reactive oxygen species (ROS) accumulation in scales, as indicated by the lower malondialdehyde (MDA) content, relative conductivity, lipoxygenase (LOX) activity, O2− production rate, and hydrogen per-oxide (H2O2) content. Further, scales treated with 0.8 mM NaHS exhibited significantly higher activities of superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), and ascorbic acid peroxidase (APX). Collectively, our data provide new insight into how the postharvest senescence of Lanzhou lily scales might be alleviated by H2S by enhancing antioxidant defense systems.

Multiple Amino Acids Inhibit Postharvest Senescence of Broccoli

The function of free amino acids in protein synthesis, as a source of energy and unique roles in catabolism have been well studied in plant development but their function in postharvest fruit and vegetables has received little attention. This study evaluated 11 amino acids—arginine, alanine, aspartic acid, glutamic acid, glycine, ornithine, phenylalanine, serine, tyrosine, tryptophan and valine—on the development of senescence of broccoli. Broccoli florets were dipped in 5 mM solution of amino acids, then stored at 10 °C in air containing 0.1 µL L−1 ethylene. Senescence was assessed by green life, ethylene production, respiration rate and ion leakage. Green life was increased by all the amino acids except valine. Similarly, ethylene production and ion leakage were decreased by all the amino acids except valine, while respiration rate was reduced by all amino acids. It is speculated that the early reduction in ethylene production could be the mechanism by which the amino acids delayed senescence. The beneficial effect of naturally occurring amino acids in inhibiting senescence has potential commercial relevance, as the amino acids have Generally Recognised As Safe (GRAS) status which should assist gain regulatory approval, and gain acceptance by consumers wary of synthetic chemicals on foods.