These tomato varieties do not exhibit a climacteric like conventional tomato varieties but remain susceptible to external ethylene.
1-Methylcyclopropene (1-MCP) is a gaseous molecule that blocks the sites of ethylene binding and action in fruit. Marketed under the commercial name ‘SmartFresh’, it is increasingly used across a wide variety of stored products where the inhibition of ethylene effects is desired. Although results show a significant extension of storage life, display life and delay in softening, there are also reports of poor aroma and flavour development in some fruits as a consequence of 1-MCP’s inhibition of the respiratory climacteric. There are no known toxicological or environmental impacts from its use.
Aminoethoxyvinylglycine (AVG) and aminooxyacetic acid (AOA) are compounds that inhibit the synthesis of ethylene within the fruit. Pre-harvest applications of these chemicals enable fruit to reach greater maturity and colour development on the tree prior to harvest. They do this by inhibiting the 1-aminocyclopropane-1-carboxylic acid (ACC) synthase enzyme. ACC synthase is thought to be the rate-limiting step in fruit for the production of internal ethylene - ACC being the precursor molecule to ethylene in the ethylene biosynthesis pathway.
It is likely that these fatty acids arise from asymbiotic relationship of bacteria with the host cells of marineinvertebrates. Two 5,9 trienoic acids have been identified for the firsttime in triacylglycerols from mollusk gonads, 5,9,15-22:3 and 5,9,15-24:3 ().
While all these unsaturated fatty acids were isolated from phospholipids, apolyethylenic fatty methyl ester (5,9,23-30:3) was isolated from a Mediterraneansponge ( Demospongiae) ().
Based on the distribution of 5,9 fatty acids it may conclude that thebiosynthetic pathways of invertebrates, sponges, myxomycetes, and some plantshave a common enzymatic system to synthesize 5,9 ethylene-interrupted dienoicacids.
Further experiments confirmed the effect of methyl jasmonate on the expression of the two YUCCA genes and further highlighted that over-expression of the two genes translates into significantly elevated indole-3-acetic acid levels. The described accumulation of YUC8 and YUC9 transcripts appears to be dependent on the canonical jasmonate receptor COI1, because the induction observed in wild type is completely missing in the coi1 genetic background (Fig. 2). Hence, our results point towards a novel connection through which jasmonate signaling and auxin biosynthesis are linked. Particularly interesting is the fact that jasmonate produced in response to mechanical wounding of leaves is sufficient to induce YUC9 expression in aerial tissue (Fig. 3).