Increase in Epidermal Planar Cell Density Accompanies Decreased Russeting of ‘Golden Delicious’ Apples Treated with Gibberellin A4+7

Abstract

<jats:p>A 2-year study was conducted in a ‘Golden Delicious’ (<jats:italic>Malus</jats:italic> ×<jats:italic>domestica</jats:italic> Borkh.) orchard with a high incidence of physiological fruit russeting to examine the effect of gibberellin A<jats:sub>4+7</jats:sub> (GA<jats:sub>4+7</jats:sub>) on apple epidermal cell size. Beginning at petal fall, four sequential applications of GA<jats:sub>4+7</jats:sub> (0, 15, or 30 mg·L<jats:sup>−1</jats:sup>) were applied to whole trees every 7–10 days with an orchard air-blast sprayer at a volume of ≈1000 L·ha<jats:sup>−1</jats:sup>. Fruit epidermal tissue samples were taken approximately monthly beginning 1 week after the fourth application. Tissue was treated in the laboratory with an enzyme mixture to remove cellular debris in preparation for examination using either light or scanning electron microscopy (SEM). In 2007, because russeting was insignificant, treatment differences could not be established. Moreover, transillumination microscopy did not permit accurate measurement of ‘Golden Delicious’ fruit epidermal planar cell area beyond midseason because the isolated cuticle became thick and multilayered. In 2008, however, respective treatments of 15 and 30 mg·L<jats:sup>−1</jats:sup> reduced calyx end russeting by 40% and 83% and increased epidermal planar cell density by 14% and 27% as measured using SEM.</jats:p>

Mechanical Properties of Apple Skin Are Determined by Epidermis and Hypodermis

“…The microcracks are highly oriented with a maximum incidence in a direction perpendicular to the applied force, which indicates a cause-and-effect relationship. Our observations are consistent with cuticular microcracks observed by SEM in the apple fruit surface (Curry, 2012;Faust and Shear, 1972b;Maguire et al, 1999;Roy et al, 1999). These microcracks are usually limited to the outer layers of the cuticle (Maguire et al, 1999) and do not extend deeply into the epidermal and hypodermal cell layers.…”

“…Throughout fruit development, cuticle material is deposited as the area of the skin surface expands with no apparent buildup of reversible elastic strain (Khanal et al, 2013a(Khanal et al, , 2013b. Nevertheless, micrographs from scanning electron microscopy (SEM) of apple fruit surfaces often reveal a network of fine cuticular cracks, even in the absence of any russeting (Curry, 2012;Faust and Shear, 1972b;Maguire et al, 1999;Roy et al, 1999). Whether these cracks are mechanically relevant in the development of fruit surface disorders is not yet known.…”

The Gibberellin Producer Fusarium fujikuroi: Methods and Technologies in the Current Toolkit

“…The constructed strain resulted in a 2.5-fold increase in GAs yield (Albermann et al, 2013). Compared to GA3, GA 4 , and GA 7 may perform more excellently when treating different plants (Kim and Miller, 2009;Curry, 2012;Qian et al, 2018). Tudzynski et al deleted the P450-3 gene and the resulted mutant could not produce GA 1 and GA 3 anymore, while the production of GA 4 and GA 7 was significantly increased (Tudzynski et al, 2003).…”

EXOGENUS ‘GA3’ AND ‘GA4+7’ EFFECTS ON PHENOLOGICAL INDICES, FROST HARDINESS AND QUALITY PROPERTIES OF ‘ENGLISH MORELLO’ SOUR CHERRY (Prunus cerasus L.)

“…GAs based products, has been applied in vegetable [Knoche and Peschel 2007], floriculture [Cardoso et al 2012], nursery [Palmer et al 2011, Pio et al 2012 and fruit industry. In fruit production GAs application is a tool used for a range of functions: to stimulate vegetative growth [Qureshi et al 2013], inhibit flower bud formation [Val et al 2001, Gonzalez-Rossia et al 2006, Lenahan and Whiting 2008, affect fruit set [Shahin et al 2010, Galván et al 2012, reduce fruit surface russeting [Knoche et al 2011, Curry 2012, induce parthenocarpic fruit Schroeder 1994, Mesejo et al 2010], dalay fruit maturity [Clayton et al 2006, Cline andTrought 2007], stimulate rachis elongation for looser fruit clusters [Hed et al 2011], enhance fruit resistance to pest infestation [Birke et al 2011] as well as to improve size and internal quality properties of fruit [Basak et al 1998, Chang and Lin 2006, Zhang and Whiting 2011a, b, Einhorn et al 2013.…”