Involvement of Multiple Types of Dehydrins in the Freezing Response in Loquat (Eriobotrya japonica)

Abstract

Dehydrins (DHNs) are a family of plant proteins typically induced in response to stress conditions that cause cellular dehydration, such as low temperatures, high salinity, and drought. Loquat (Eriobotrya japonica) is a perennial fruit crop that blossoms during winter. Loquat fruitlets are frequently injured by freezing. To evaluate the role of the EjDHNs in freezing resistance in loquat fruitlets, two cultivars of loquat, the freezing-sensitive ‘Ninghaibai’ (FS-NHB) and the freezing-tolerant ‘Jiajiao’ (FT-JJ), were analyzed under induced freezing stress. Freezing stress led to obvious accumulation of reactive oxygen species and considerable lipid peroxidation in membranes during the treatment period. Both these phenomena were more pronounced in ‘FS-NHB’ than in ‘FS-JJ.’ Immunogold labeling of dehydrin protein was performed. DHN proteins were found to be concentrated mainly in the vicinity of the plasma membrane, and the density of the immunogold labeling was significantly higher after freezing treatment, especially in the more freezing-tolerant cultivar ‘FT-JJ.’ Seven DHNs, showing four different structure types, were obtained from loquat fruitlets and used to study the characteristics of different EjDHN proteins. These DHN proteins are all highly hydrophilic, but they differ significantly in size, ranging from 188 to 475 amino acids, and in biochemical properties, such as theoretical pI, aliphatic index, and instability index. Freezing treatment resulted in up-regulation of the expression levels of all seven EjDHNs, regardless of structure type. The accumulation of the transcripts of these EjDHN genes was much more pronounced in ‘FT-JJ’ than in ‘FS-NHB.’ Altogether, this study provides evidence that EjDHNs are involved in the cryoprotection of the plasma membrane during freeze-induced dehydration in loquat fruitlets.

Transcriptomic Analysis of the Underground Renewal Buds during Dormancy Transition and Release in ‘Hangbaishao’ Peony (Paeonia lactiflora)

“…Five of these ten unigenes (Unigene 028024, Unigene 048324, Unigene 022315, Unigene 033567 and Unigene 022968) were annotated as DHN by NR from sequences of Malus × domestica , Corylus heterophylla and Phaseolus vulgaris . DHNs comprise one of the plant protein families typically induced by multiple stresses that cause cellular dehydration, and protect plant proteins and membranes from damage[ 68 , 69 ]. BjDHN2 and BjDHN3 exert a protective function on membranes under abiotic stresses, both of which are upregulated by low temperature, drought and salt stress in Brassica juncea [ 68 ].…”

Study on the expression of dehydrin genes and activities of antioxidativeenzymes in floral buds of two sand pear (Pyrus pyrifolia Nakai) cultivarsrequiring different chilling hours for bud break

“…With a decrease in temperature during dormancy, the amount of ROS increased, which can be seen in the increase of H 2 O 2 content in the present study ( Figure 5). Xu et al (2014) reported that H 2 O 2 content was high after cold temperature treatment in loquat fruitlets. SOD is the main enzyme responsible for scavenging ROS and for converting it into oxygen and H 2 O 2 (Cruzde-Carvalho, 2008), but in our results, increases in H 2 O 2 content were accompanied by decreases in SOD activity.…”

Physiological and transcriptome analysis of Poa pratensis var. anceps cv. Qinghai in response to cold stress

“…The peroxidase (POD, EC 1.11.1.7) activity was measured according to Chance and Maehly [68]. The activities of catalase (CAT, EC 1.11.1.6) and ascorbate peroxidase (APX, EC 1.11.1.11) were determined according to Xu et al [69]. The specific primers of C-repeat binding factors (CBFs) were designed according to Zhang et al [70].…”