Zhiguo Ju

Evidence that α-farnesene biosynthesis during fruit ripening is mediated by ethylene regulated gene expression in apples

Abstract The effect of ethylene regulation on α-farnesene biosynthesis in preclimateric ‘Delicious’ and ‘Granny Smith’ apples was studied using an ethylene inducer and inhibitor, α-farnesene biosynthesis precursors, and protein transcription and translation inhibitors. α-Farnesene was not detectable when internal ethylene concentrations were less than 1 μl l −1 . Correlations between internal ethylene and α-farnesene production fit the exponential growth equation and were significant in ‘Delicious’ ( y = e 0.17 ; r 2 =0.68) and ‘Granny Smith’ ( y = e 0.18 ; r 2 =0.83). When applied at harvest, aminoethoxyvinylglycine (AVG) at 200 mg l −1 inhibited both internal ethylene accumulation and α-farnesene production, whereas ethephon at 200 mg l −1 accelerated both. Adding ethephon to AVG-treated fruit after 18 days at 20°C induced internal ethylene accumulation and α-farnesene production. Ethephon induced α-farnesene production in discs from preclimacteric fruit peel as well as AVG-treated fruit peel, but α-farnesene was undetectable when cycloheximide (CHI, 50 mM), actinomycin D (Act D, 50 mM), or silver nitrate (150 mg l −1 ) were added to the ethephon-treated discs. In preclimacteric fruit discs at harvest, with or without AVG treatment, α-farnesene biosynthesis was induced by 50 μM mevalonic acid lactone (MAL) or farnesyl pyrophosphate (FPP), but not by hydroxymethylglutaric acid (HMG). Adding CHI or Act D to these discs did not affect the induction of α-farnesene by MAL or FPP.

Mono-, di-, and tri-acylglycerols and phospholipids from plant oils inhibit scald development in 'Delicious' apples.

Effects of emulsions of plant oils (soybean, corn, olive, peanut, linseed, and cottonseed) and oil components on scald development in ‘Delicious’ apples (Malus domestica Borkh) were studied. Prestorage treatments with emulsions of different commercial plant oils reduced scald to the same level after 6 months of cold storage but were not as effective as 2000 mg l−1 diphenylamine (DPA). Oil components affected scald to different degrees. At emulsion strengths of 6 and 9% (w/v) neutral lipids (mono-, di-, and tri-acylglycerols) or phospholipids inhibited scald to DPA treatment levels, while α-tocopherol at 0.5–3% (w/v) increased scald development. Scald inhibition between saturated and unsaturated neutral lipids or among different acylated neutral lipids was similar. Plant oils stripped of α-tocopherol at 6 or 9% controlled scald (<4%) to DPA treatment levels when blank control developed 60% scald and about 15–20% of unstripped plant oil-treated fruit developed scald. Fruit treated with emulsions of oil or lipids did not show greasiness and did not develop off flavor after storage.

Corn oil emulsion for early bloom thinning of trees of ‘Delicious’ apple, ‘Feng Huang’ peach, and ‘Bing’ cherry

Summary Corn oil emulsions at 1%, 3%, or 5% were sprayed to ‘Delicious’ apple, ‘Feng Huang’ peach, and ‘Bing’ cherry trees at prebloom, 20%, 50%, and 80% full bloom (FB), respectively, and the effects of these combinations on bloom thinning, fruit set, foliage injury, and return bloom were studied. The thinning effect of oil emulsion was concentration and application time dependent, with the higher concentration applied earlier being most effective. On apple and peach trees, 3% to 5% of corn oil applied between prebloom and 20% FB thinned adequately. They were less effective when applied at 50% FB and were not effective at 80% FB. At 1%, oil emulsion was not effective even when applied at early stages. In cherries, oil emulsions at 1% and 3% applied at prebloom to 20% FB thinned fruit to acceptable degrees. Oil at 5%, however, over thinned. Oil emulsion was less effective when applied at 50% FB and not effective at 80% FB even at high oil concentrations. Oil at 3% or 5% applied at 20% FB increased fruit weight and soluble solids but reduced total yields in cherries. Oil treatments did not injure fruit or foliage either at application or afterwards. Return bloom wasnot affected in peaches and cherries but was improved in apples by oil treatment.

Stripped plant oils maintain fruit quality of 'Golden Delicious' apples and 'Bartlett' pears after prolonged cold storage.

Summary Effects of stripped (α-tocopherol reduced) plant oils (corn, soybean, peanut, cottonseed, and linseed) on ethylene, fruit firmness, colour, titratable acidity (TA), and soluble solids content (SSC) were evaluated in ‘Golden Delicious’ apples after six months’ and ‘Bartlett’ pears after six weeks’ storage at 08C. All oils similarly inhibited ethylene production and accumulation in the first two weeks in ‘Bartlett’ and in the first three months in ‘Golden Delicious’. Compared with the untreated controls, oil-treated fruit were firmer, greener, and contained a higher level of TA after six weeks or six months at 0°C plus 7.d at 20°C. Treating with 200.μl.l–;1 propylene for 6.h at harvest stimulated ethylene production, accelerated fruit softening and degreening, and reduced acidity after cold storage in untreated apples and pears. In oil-treated fruit, however, propylene treatment was ineffective. SSC was not affected by oil or propylene treatment. During one week of storage at 20°C, ethylene production and changes in fruit firmness, colour, and acidity were reduced by oil treatments applied to fruit at harvest (preclimacteric) or applied to fruit after one month of storage at 08°C (climacteric). The effectiveness of oil treatment, however, was higher in preclimacteric than in climacteric fruit.

Different responses of `Snow Giant' and `Elegant Lady' peaches to fruit maturity and storage temperature

Summary The susceptibility of ‘Elegant Lady’ and ‘Snow Giant’ peaches (Prunus persica Batsch) to mealiness, leatheriness, flesh browning (FB), and gel breakdown (GB) were studied using fruit harvested at different maturity and stored at 08 or 58C. ‘Elegant Lady’ developed 10% mealiness and 4% leatheriness without developing leatheriness and GB after four weeks of storage at 08C. At 58C, however, it had 46% mealiness and 12% FB without developing leatheriness and GB after the same period of storage. Fruit from the last harvest developed more mealiness than those from the two early harvests. ‘Snow Giant’ developed 92% leatheriness and FB and 68% GB without developing mealiness after five weeks at 08C. All FB and GB were found in leathery fruit. Fruit from the last harvest developed less leatheriness, FB, and GB than those from the first two harvests. When stored at 58C, fruit did not develop leatheriness. A low level of mealiness (10%) was found only in fruit from the third harvest. Correlations between mealiness and FB (r2.=.0.47), leatheriness and FB (r2.=.0.78), and leatheriness and GB (r2 =.0.71) were significant. Mealiness was not correlated to GB. Leathery fruit from both cultivars produced less ethylene, were firmer, and contained lower levels of polygalacturonase (PG) activity and higher levels of insoluble pectin than mealy and juicy fruit. There were no diffferences in these measurements between mealy and juicy fruit.