Constitutive expression of apple endo-POLYGALACTURONASE1 in fruit induces early maturation, alters skin structure and accelerates softening.

During fruit ripening, polygalacturonases (PGs) are key contributors to the softening process in many species. Apple is a crisp fruit that normally exhibits only minor changes to cell walls and limited fruit softening. Here, we explore the effects of PG overexpression during fruit development using transgenic apple lines overexpressing the ripening-related endo-POLYGALACTURONASE1 gene.

Stress, senescence, and specialized metabolites in bryophytes.

Life on land exposes plants to varied abiotic and biotic environmental stresses. These environmental drivers contributed to a large expansion of metabolic capabilities during land plant evolution and species diversification. In this review we summarize knowledge on how the specialized metabolite pathways of bryophytes may contribute to stress tolerance capabilities.

Transcriptome Responses of Ripe Cherry Tomato Fruit Exposed to Chilling and Rewarming Identify Reversible and Irreversible Gene Expression Changes.

Tomato fruit stored below 12°C lose quality and can develop chilling injury upon subsequent transfer to a shelf temperature of 20°C. The more severe symptoms of altered fruit softening, uneven ripening and susceptibility to rots can cause postharvest losses. We compared the effects of exposure to mild (10°C) and severe chilling (4°C) on the fruit quality and transcriptome of 'Angelle', a cherry-type tomato, harvested at the red ripe stage.

Salicylic acid treatment mitigates chilling injury in peach fruit by regulation of sucrose metabolism and soluble sugar content.

Peach fruit stored in the cold are susceptible to chilling injury. A pre-storage treatment with the natural hormone salicylic acid can alleviate chilling damage, although the mechanism is unclear. We found that a treatment with 1 μmol L salicylic acid for 15 min prior to storage at 4 °C delayed and reduced fruit internal browning, a symptom of chilling injury.

Strigolactones regulate sepal senescence in Arabidopsis.

Flower sepals are critical for flower development and vary greatly in life span depending on their function post-pollination. Very little is known about what controls sepal longevity. Using a sepal senescence mutant screen, we identified two Arabidopsis mutants with delayed senescence directly connecting strigolactones with senescence regulation in a novel floral context that hitherto has not been explored.

Sensing when the wall comes tumbling down.

This article comments on: . 2020. Elucidating the role of polygalacturonase genes in strawberry fruit softening.

Jasmonic acid treatment alleviates chilling injury in peach fruit by promoting sugar and ethylene metabolism.

Peach (Prunus persica L.) fruit are highly susceptible to chilling injury during cold storage, resulting in internal flesh browning and a failure to soften normally. We have examined the effect of a postharvest treatment consisting of a brief (30 s) dip in the natural plant hormone jasmonic acid, prior to storage at 4 °C.

The Evolution of Flavonoid Biosynthesis: A Bryophyte Perspective.

The flavonoid pathway is one of the best characterized specialized metabolite pathways of plants. In angiosperms, the flavonoids have varied roles in assisting with tolerance to abiotic stress and are also key for signaling to pollinators and seed dispersal agents. The pathway is thought to be specific to land plants and to have arisen during the period of land colonization around 550-470 million years ago.

A manually annotated Actinidia chinensis var. chinensis (kiwifruit) genome highlights the challenges associated with draft genomes and gene prediction in plants.

Background: Most published genome sequences are drafts, and most are dominated by computational gene prediction. Draft genomes typically incorporate considerable sequence data that are not assigned to chromosomes, and predicted genes without quality confidence measures. The current Actinidia chinensis (kiwifruit) 'Hongyang' draft genome has 164 Mb of sequences unassigned to pseudo-chromosomes, and omissions have been identified in the gene models.

Simultaneous knock-down of six β-galactosidase genes in petunia petals prevents loss of pectic galactan but decreases petal strength.

Galactose (Gal) is incorporated into cell wall polysaccharides as flowers open, but then is lost because of β-galactosidase activity as flowers mature and wilt. The significance of this for flower physiology resides in the role of galactan-containing polysaccharides in the cell wall, which is still largely unresolved. To investigate this, transcript accumulation of six cell wall-associated β-galactosidases was simultaneously knocked down in 'Mitchell' petunia (Petunia axillaris x (P.

The Onion ( L.) Gene Regulates Anthocyanin Biosynthesis.

Bulb color is an important consumer trait for onion ( L., Allioideae, Asparagales). The bulbs accumulate a range of flavonoid compounds, including anthocyanins (red), flavonols (pale yellow), and chalcones (bright yellow).

Composition and structure of tuber cell walls affect in vitro digestibility of potato (Solanum tuberosum L.).

The digestibility of starchy foods, such as potatoes, can be characterized by the proportion of starch that is rapidly digestible by in vitro hydrolysis (rapidly digestible starch, RDS). This study evaluated the RDS content in a potato germplasm collection consisting of 98 genotypes and identified three advanced lines, Crop39, Crop71 and Crop85, where cooked potato RDS content was significantly lower than that of their respective isolated starches (P < 0.05).

Staying green postharvest: how three mutations in the Arabidopsis chlorophyll b reductase gene NYC1 delay degreening by distinct mechanisms.

Stresses such as energy deprivation, wounding and water-supply disruption often contribute to rapid deterioration of harvested tissues. To uncover the genetic regulation behind such stresses, a simple assessment system was used to detect senescence mutants in conjunction with two rapid mapping techniques to identify the causal mutations. To demonstrate the power of this approach, immature inflorescences of Arabidopsis plants that contained ethyl methanesulfonate-induced lesions were detached and screened for altered timing of dark-induced senescence.

Overexpression of STARCH BRANCHING ENZYME II increases short-chain branching of amylopectin and alters the physicochemical properties of starch from potato tuber.

Background: Starch is biosynthesised by a complex of enzymes including various starch synthases and starch branching and debranching enzymes, amongst others. The role of all these enzymes has been investigated using gene silencing or genetic knockouts, but there are few examples of overexpression due to the problems of either cloning large genomic fragments or the toxicity of functional cDNAs to bacteria during cloning. The aim of this study was to investigate the function of potato STARCH BRANCHING ENZYME II (SBEII) using overexpression in potato tubers.

Lower cell wall pectin solubilisation and galactose loss during early fruit development in apple (Malus x domestica) cultivar 'Scifresh' are associated with slower softening rate.

Substantial differences in softening behaviour can exist between fruit even within the same species. Apple cultivars 'Royal Gala' and 'Scifresh' soften at different rates despite having a similar genetic background and producing similar amounts of ethylene during ripening. An examination of cell wall metabolism from the fruitlet to the ripe stages showed that in both cultivars pectin solubilisation increased during cell expansion, declined at the mature stage and then increased again during ripening.

Crystal structure of kiwellin, a major cell-wall protein from kiwifruit.

Kiwellin is a cysteine-rich, cell wall-associated protein with no known structural homologues. It is one of the most abundant proteins in kiwifruit (Actinidia spp.), and has been shown to be recognised by IgE of some patients allergic to kiwifruit.

An enzyme activity capable of endotransglycosylation of heteroxylan polysaccharides is present in plant primary cell walls.

Heteroxylans in the plant cell wall have been proposed to have a role analogous to that of xyloglucans or heteromannans, forming growth-restraining networks by interlocking cellulose microfibrils. A xylan endotransglycosylase has been identified that can transglycosylate heteroxylan polysaccharides in the presence of xylan-derived oligosaccharides. High activity was detected in ripe fruit of papaya (Carica papaya), but activity was also found in a range of other fruits, imbibed seeds and rapidly growing seedlings of cereals.

Post-translational regulation of acid invertase activity by vacuolar invertase inhibitor affects resistance to cold-induced sweetening of potato tubers.

Cold-induced sweetening (CIS) is a serious post-harvest problem for potato tubers, which need to be stored cold to prevent sprouting and pathogenesis in order to maintain supply throughout the year. During storage at cold temperatures (below 10 °C), many cultivars accumulate free reducing sugars derived from a breakdown of starch to sucrose that is ultimately cleaved by acid invertase to produce glucose and fructose. When affected tubers are processed by frying or roasting, these reducing sugars react with free asparagine by the Maillard reaction, resulting in unacceptably dark-coloured and bitter-tasting product and generating the probable carcinogen acrylamide as a by-product.