The Relationship between the Expression of Ethylene-Related Genes and Papaya Fruit Ripening Disorder Caused by Chilling Injury

Abstract

Papaya (Carica papaya L.) is sensitive to low temperature and easy to be subjected to chilling injury, which causes fruit ripening disorder. This study aimed to investigate the relationship between the expression of genes related to ethylene and fruit ripening disorder caused by chilling injury. Papaya fruits were firstly stored at 7°C and 12°C for 25 and 30 days, respectively, then treated with exogenous ethylene and followed by ripening at 25°C for 5 days. Chilling injury symptoms such as pulp water soaking were observed in fruit stored at 7°C on 20 days, whereas the coloration and softening were completely blocked after 25 days, Large differences in the changes in the expression levels of twenty two genes involved in ethylene were seen during 7°C-storage with chilling injury. Those genes with altered expression could be divided into three groups: the group of genes that were up-regulated, including ACS1/2/3, EIN2, EIN3s/EIL1, CTR1/2/3, and ERF1/3/4; the group of genes that were down-regulated, including ACO3, ETR1, CTR4, EBF2, and ERF2; and the group of genes that were un-regulated, including ACO1/2, ERS, and EBF1. The results also showed that pulp firmness had a significantly positive correlation with the expression of ACS2, ACO1, CTR1/4, EIN3a/b, and EBF1/2 in fruit without chilling injury. This positive correlation was changed to negative one in fruit after storage at 7°C for 25 days with chilling injury. The coloring index displayed significantly negative correlations with the expression levels of ACS2, ACO1/2, CTR4, EIN3a/b, ERF3 in fruit without chilling injury, but these correlations were changed into the positive ones in fruit after storage at 7°C for 25 days with chilling injury. All together, these results indicate that these genes may play important roles in the abnormal softening and coloration with chilling injury in papaya.

Comparative metabolites profiling of harvested papaya (Carica papaya L.) peel in response to chilling stress

“…Whereas, papaya fruit is considered to be susceptible to cold storage . Temperatures below 7 °C induce CI in papaya fruits and cause fruit ripening disorder . As shown in Fig.…”

“…Papaya ( Carica papaya L.) fruit is one of the most important tropical fruits in the world. As a typical climacteric fruit, papaya fruit has rapid softening and yellowing processes, which results in short‐term shelf life during postharvest storage . Therefore, despite its high nutritional value and demand on the market, papaya fruit is rather difficult to preserve and commercialize .…”

“…However, papaya is easily subjected to chilling injury (CI) when stored at low temperature. Temperatures below 7 °C induce CI in papaya fruits and cause fruit ripening disorder . Additionally, cold temperature has been reported to affect fruit metabolism and result in loss of flavor .…”

Ethylene‐responsive factor 4 is associated with the desirable rind hardness trait conferring cracking resistance in fresh fruits of watermelon

“…The ripening process of climacteric fruit is accompanied by a peak in ethylene production and thus results in a dramatic decrease in fruit hardness (Costa et al , ). ERFs, signal factors that bridge the internal and external signal and ethylene response, play important roles in stress responses (Liu et al , , , ; Zou et al , ), growth and development (Yin et al , ) and senescence (Tomotsugu et al , ). It has been reported that ERFs could be candidate genes for fruit firmness.…”

Plant Hormones under Challenging Environmental Factors

“…By contrast, in the cold-sensitive Fortune mandarin, the continuous ET application during cold storage induces cold tolerance through the increase of CAT and PAL activities . However, the induction of ACS and ACO gene expression during lowtemperature storage does not represent an accurate indicator of cold tolerance since it has been described in cold-sensitive citrus fruit (Maul et al 2011 ;Lado et al 2014Lado et al , 2015, papaya (Zou et al 2014 ), and zucchini (Megías et al 2014 ), whereas it was not observed in grapefruit cold-resistant tissues (Lado et al 2015 ). However, the induction of ACS and ACO gene expression during lowtemperature storage does not represent an accurate indicator of cold tolerance since it has been described in cold-sensitive citrus fruit (Maul et al 2011 ;Lado et al 2014Lado et al , 2015, papaya (Zou et al 2014 ), and zucchini (Megías et al 2014 ), whereas it was not observed in grapefruit cold-resistant tissues (Lado et al 2015 ).…”