Cell wall-related genes studies on peach cultivars with differential susceptibility to woolliness: looking for candidates as indicators of chilling tolerance

Abstract

The results obtained indicate that a β-xylosidase gene may act as good indicator of chilling tolerance and provide new insights into the complex issue of peach fruit woolliness. The storage of peaches at low temperatures for prolonged periods can induce a form of chilling injury (CI) called woolliness, characterized by a lack of juiciness and a mealy texture. As this disorder has been associated with abnormal cell wall dismantling, the levels of 12 transcripts encoding proteins involved in cell wall metabolism were analysed in cultivars with contrasting susceptibility to this disorder selected from five melting flesh peach cultivars. The resistant ('Springlady') and susceptible ('Flordaking') cultivars displayed differences in the level of expression of some of the selected genes during fruit softening and in woolly versus non-woolly fruits. From these genes, the level of expression of PpXyl, which encodes for a putative β-xylosidase, was the one that presented the highest correlation (negative) with the susceptibility to woolliness. PpXyl expression was also analysed in a cultivar ('Rojo 2') with intermediate susceptibility to woolliness, reinforcing the conclusion about the correlation of PpXyl expression to the presence of woolliness symptom. Moreover, the level of expression of PpXyl correlated to protein level detected by Western blot. Analyses of the promoter region of the PpXyl gene (1637 bp) isolated from the three cultivars showed no differences suggesting that cis-elements from other regions of the genome and/or trans elements could be responsible of the differential PpXyl expression patterns. Overall, the results obtained indicate that PpXyl may act as a good indicator of woolliness tolerance and that the regulation of expression of this gene in different cultivars does not depend on sequences upstream the coding sequence.

Transcriptomic and metabolic analyses provide new insights into chilling injury in peach fruit

“…In this study, the increased transcript abundance of Exp1‐3 , PYL1‐3 , Xyl , EGase and XTH2 in LTC was maintained following transfer to a lower temperature, 0 °C (Figs & a). This is similar to the findings that Exp protein levels were lower in CI peach fruit than non‐CI fruit (Obenland et al ) and Xyl showed the highest correlation with peach susceptibility to CI (Genero et al ). In other plants, enhanced Exp and XTH mRNA concentrations were also highlighted as enabling adaptation and/or resistance to abiotic stresses (Shi et al ; Le Gall et al ).…”

Differential lipidome remodeling during postharvest of peach varieties with different susceptibility to chilling injury

“…S1). The cold storage treatment at 0°C for 21 days was selected because it successfully discriminates peach varieties according to their different degrees of resistance/susceptibility to chilling injuries (CI) (Bustamante et al , Genero et al ). After 21 days at 0°C, fruits were stored at 20°C for ripening (CS21 + RS fruits, Fig.…”

“…Firmness and soluble solid content were measured in fruits from all postharvest conditions (H, RS, CS, CS21 and CS21 + RS) and described in Table S2 and Bustamante et al (). The amount of expressible juice measured in RS and CS21 + RS fruits (Table S2) allowed us to classify the varieties in: susceptible (FD and R2) and resistant (EL, LM, RG and SL) to CI as reported in Genero et al () and Bustamante et al (). Other CI symptoms, such as flesh browning or internal reddening, were not detected in the varieties selected and the postharvest conditions applied in the present work.…”

“…In the present work, the differential remodeling of the lipidome during the postharvest of peach varieties with contrasting susceptibility to CI was investigated. These varieties have been previously characterized in detail (Bustamante et al , Genero et al , Monti et al ), allowing the question of how variation in chilling tolerance between these fruits is reflected in their lipid composition. In addition, the common changes in the lipidome of the six varieties were also analyzed after storage of fruits at ambient or low temperature, providing information about the general responses to normal ripening and low temperature stress, respectively.…”

Effect of Ethylene on Cell Wall and Lipid Metabolism during Alleviation of Postharvest Chilling Injury in Peach

“…Expressions of polygalacturonase (PG), pectate lyase (PLY) and expansin (Exp) increase during fruit softening [15,16]. Exp as well as cell wall hydrolase genes PLY, xylosidase (Xyl), β-1, 4-endoglucanase (EGase) and xyloglucan endo-transglucosylase/hydrolase (XTH2) displayed lower transcript abundance in fruit with CI [1,17].…”