Ethylene Biosynthesis.new

44
ETHYLENE

description

postharvest, ethylene biosynthesis,

Transcript of Ethylene Biosynthesis.new

Siti fairuz yusoff

ETHYLENE1INTRODUCTIONEthylene? (C2H4)-naturally produced, simple two carbon gaseous plant growth regulator -effect on the growth, development and storage life of many fruits, vegetables and ornamental crops.

H2C=CH22Beneficial effects ethylene on fresh fruit and vegetables:Promote color development in fruitStimulate ripening on fruitPromotes degreening of citrusStimulates dehiscense in nutsAlters sex expressions in the cucurbitaceaePromotes flowering in bromeliaceae (Pineapple)

3Detrimental effects of ethylene on fresh fruits and vegetables:Accelarates senescenseStimulates chlorophyll loss (eg. Yellowing)Enhance excessive softening in fruitsStimulate sprouting of potatoPromotes abscision of leaves and flowerPromotes discoloration (eg. Browning)Hastens thoughening of vegetables.4

Impacts of ethylene on post harvest quality of fruits and vegetables (Suslow, 2000)

Russet spotting of lettuce (dark brown spotting on the mid-ribs of lettuce leaves)Yellowing or loss of green color (for example, in cucumber, broccoli, kale, spinach)Increased toughness in turnips and asparagus spearsIncrease or decrease sprouting in potatoesYellowing and abscission (dropping) of leaves in BrassicasSoftening, pitting, and development of off-flavor in peppers, summer squash, and watermelonsBrowning and discoloration in eggplant pulp and seedDiscoloration and off-flavor in sweet potatoesIncreased ripening and softening of mature green tomatoesDevelopment of bitter taste in carrots and parsnips

5Discovery of ethylene..

6Cont..

7

The biosynthesis pathway discovered by Yang in the 1980s

8

9The ethylene synthesis precursor and enzyme are correlated with ethylene production.

10

11a. Fruit ripening

12

13

14

After Ethylene treatment15

16b. Flower wilting

17

The highest increasing concentration of ethylene is at day 6 after harvest and cause the wilting to flower .18

Ethephon treatment on pineapple to induce floweringc. Induce flowering19d. Senescense

20

21d. Leaves dropping

22e. Degreening of citrus

23Manipulating of EthyleneBiosynthetic Pathway of Ethylene Synthesismethionine s-adenosylmethionine 1-aminocyclopropane-1-carboxylic acid ethyleneEthylene inhibitors - chemicals that inhibit the synthesis or action of ethylene1. Ethylene Synthesis Inhibitors (block synthesis of SAM ACC): block ethylene productionAVG - aminoethoxyvinyl glycineMVG - methoxyvinyl glycine AOA - aminoacetic acid

242. Ethylene Action Blockers (ethylene block action)STS - silver thiosulfate CO2 - carbon dioxideNi nickel Co cobaltMCP 1-mehtylcyclopropane it is a gas that can saturate the receptor sites, and block action for several daysEthylBloc commercial compound

25Ethylene - STSThe ethylene cell-membrane receptor protein appears to include a copper cofactor and can also be eliminated when the receptor binds to silver (Ag+) ions such as silver thiosulfate. The silver thiosulfate can thus be added to a vase to increase the vase-life of a bouquet of flowers.

26

27

In normal condition, ethylene will cause the wilting of the flower (non-pretreated)28

But, if the rose samantha treated with silver tiosulphate (STS), it will delay the wilting on the cut flower and the flower maintain fresh.29

Representative ethylene-treated roses (E) and untreated (A) from different pre treatments at 7 days.Samantha roses included among the ethylene sensitive variety. STS was observed to protect ethylene-sensitive roses from ethylene.STS reduced the sensitivity of roses to ethylene.So that promotive effect was observed lead to petal closure30b. Ethylene- mcp

Binding of ethylene molecule with the receptor unlocks the receptor and leads to a chemical reaction in the plant tissue (diagram by Jenny Bower, Dept. of Pomology, UC Davis).Ethylene receptors are embedded in the cell.Ethylene molecules in the air bind onto the receptors.Ethylene molecules act acts like a key unlocking the receptor.A chemical signal is sent to the cell and ethylene molecules release.31When 1-methylcyclopropene (1-MCP) binds to the ethylene receptor, it does not unlock the receptor and remains locked to the receptor preventing the binding of ethylene and the chemical reaction does not occur (diagram by Jenny Bower, Dept. of Pomology, UC Davis).

Molecules of MCP also bind to ethylene receptors.However, MCP does not unlock the ethylene receptors, so no message sentMCP is not released, so molecules ethylene are unable to bind the receptor.Eventually, new ethylene receptors may be formed and the cell again sensitivity to ethylene.32

33

343. Temperaturerespiration decreases when temperature decreases. respiration ceases at about freezing temperatures (32 oF) increasing temperature increases respiration, until temperature gets too high, then respiration decreases when tissue deteriorates

354. Oxygenrespiration decreases when oxygen decreases under very low to no oxygen, anaerobic respiration occurs.

36Other sources which affect the ethylene produce..Combustion enginesCigarette smoke, Natural gas leaks. Exposure from both natural sources (i.e. climacteric fruit or veggies being stored with non-climacteric ) All ethylene-producing sourcesCalcium carbide BUT not safe for ripeningWHY??acetylene gas, contain traces of arsenic and phosphorus, both highly toxic to humans, and the use of this chemical for ripening is illegal in most countries.37Steps to reduce ethylene exposure during storage (Jobling, 2000)

Do not store or transport green leafy vegetables with ripening fruit (apples, pears, mangoes, tomatoes, bananas).Use electric powered equipment in storage areas versus gas powered.Remove overripe or rotting fruit from storage loads (these produce higher amounts of ethylene).Avoid storing ethylene sensitive products with products that produce high levels of ethylene.Increase the ventilation rate of the storage area, assuming that the outside air is ethylene free.Use ethylene scrubbers in storage areas to remove ethylene in the air. (KMNO4)/ Charcoal.

38INTERACTION ETHYLENE -AUXINThe relationship ethylene-auxin:

To control the leaves drop.The old leaves-less produce auxin hormone. This will cause the abscission layer be more sensitive to ethylene. Effect: the production of ethylene will increase and inhibit the auxin production

39

40INTERACTION ETHYLENE ABSCISIC ACID

ABA is effective inhibiting root growth if the ethylene content is loweredmutations that block the ethylene response pathway, such as ein2, actually reduce the inhibition of growth by ABA; that is, ABA sensitivity is diminished.ABA act ethylene signal transduction pathway to inhibit root elongation, ethylene and ABA compete with each other to activate that pathway . This would explain how high levels of ethylene can reduce ABA sensitivity

41SA is involved in endogenous signaling, mediating in plant defense against pathogens.[4] It plays a role in the resistance to pathogens by inducing the production of pathogenesis-related proteins.[5] It is involved in the systemic acquired resistance (SAR) in which a pathogenic attack on one part of the plant induces resistance in other parts. The signal can also move to nearby plants by salicyclic acid being converted to the volatile ester, methyl salicylateINTERACTION ETHYLENE SALICYLIC ACID

42INTERACTION ETHYLENE JASMONIC ACID

It has an important role in response to wounding of plants and systemic acquired resistance. When plants are attacked by insects, they respond by releasing JA, which inhibits the insects' ability to digest protein.43THANK YOU44