Genetic analysis of a white-to-red berry skin color reversion and its transcriptomic and metabolic consequences in grapevine (Vitis vinifera cv. ‘Moscatel Galego’)

Background Somatic mutations occurring within meristems of vegetative propagation material have had a major role in increasing the genetic diversity of the domesticated grapevine (Vitis vinifera subsp. vinifera). The most well studied somatic variation in this species is the one affecting fruit pigmentation, leading to a plethora of different berry skin colors. Color depletion and reversion are often observed in the field. In this study we analyzed the origin of a novel white-to-red skin color reversion and studied its possible metabolic and transcriptomic consequences on cv. ‘Muscat à Petits Grains Blancs’ (synonym cv. ‘Moscatel Galego Branco’), a member of the large family of Muscats. Results The mild red-skinned variant (cv. ‘Muscat à Petits Grains Rouge’, synonym cv. ‘Moscatel Galego Roxo’), characterized by a preferential accumulation of di-hydroxylated anthocyanins, showed in heterozygosis a partially-excised Gret1 retrotransposon in the promoter region of the MYBA1 anthocyanin regulator, while MYBA2 was still in homozygosis for its non-functional allele. Through metabolic (anthocyanin, resveratrol and piceid quantifications) and transcriptomic (RNA-Seq) analyses, we show that within a near-isogenic background, the transcriptomic consequences of color reversion are largely associated to diminished light/UV-B responses probably as a consequence of the augment of metabolic sunscreens (i.e. anthocyanins). Conclusions We propose that the reduced activity of the flavonoid tri-hydroxylated sub-branch and decreased anthocyanin synthesis and modification (e.g. methylation and acylation) are the potential causes for the mild red-skinned coloration in the pigmented revertant. The observed positive relation between anthocyanins and stilbenes could be attributable to an increased influx of phenylpropanoid intermediaries due to the replenished activity of MYBA1, an effect yet to be demonstrated in other somatic variants.

“Crispy” Blackberry Genotypes: A Breeding Innovation of the University of Arkansas Blackberry Breeding Program

The University of Arkansas (UA) blackberry breeding program began in 1964, with the aim to provide high-quality fruit to the fresh market industry. One of the important traits for successful blackberry (Rubus subgenus Rubus Watson) postharvest handling is flesh firmness, so developing cultivars with high firmness is a top priority for the fresh market blackberry breeding programs across the world. In particular, the Arkansas blackberry program has a wide range of genotypes with exceptional firmness characteristics, including fruit with a unique crispy texture and firmness. During 2013 and 2014, fruit firmness measurements were done on 15 Arkansas genotypes including those with crispy and noncrispy textures. Firmness measurements consisted of fruit compression, skin drupelet penetration, and receptacle penetration. Confocal photos were taken on sections of berries of a subset of crispy and noncrispy genotypes, and color reversion was evaluated among these genotypes after storage. Compression force values differentiated crispy and noncrispy genotypes, with average values of 11.8 Newton (N) and 8.0 N, respectively. Drupelet penetration force was also higher for crispy genotypes averaging 0.23 N and noncrispy 0.15 N; similarly, receptacle penetration force averaged 0.20 N for crispy and 0.18 N for noncrispy genotypes. Visual inspection of fruit tissue revealed that drupelet mesocarp cells and receptacle cells and cell walls of crispy genotypes maintained their structure during ripening and did not break apart, whereas noncrispy genotypes did not maintain their structure and cellular integrity. Color reversion is a postharvest disorder in which drupelets of blackberry fruits turn red after being black at harvest. Therefore, it has a negative impact for growers, shippers, and consumers. After storage at 5 °C for 7 days, crispy genotypes expressed low levels of reversion compared with noncrispy genotypes. For crispy genotypes, 13.2% of drupelets developed color reversion, whereas a 41.0% developed this disorder in noncrispy genotypes, implying a better postharvest potential of this texture.

Effect of Neutral Xylanase Pretreatment on ECF Bleaching of KP Bamboo Pulp with Low Kappa Number

At present, most of the studies of Xylanase auxiliary bleaching focused on in the alkaline or acid conditions. It was investigated in this paper that Neutral Xylanase had been used to pretreat the oxygen delignified KP bamboo pulp with low kappa number. The effect of Xylanase on the follow-up ECF bleaching was discussed, especially highlighting the principle of the residual lignin removal and improvement of pulp’s brightness. Results showed that the effect of neutral xylanase pretreatment on ECF bleaching of KP bamboo pulp was obvious. The pulp with a higher brightness and brightness stability could be obtained in this way. The optimum charge of xylanase is 0.6IU•g-1, and The brightness of the bleached pulp could reach 87.8%ISO, the color reversion value 0.016, viscosity 764mL•g-1. It was 2.9%ISO higher in brightness, 59mL•g-1 higher in viscosity, but the color reversion value is only 30.2% of the later, compared to the pulp without xylanase pretreatment.