Involvement of multiple types of dehydrins in the freezing response in loquat (Eriobotrya japonica).
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.
Laboratory of Fruit Quality Biology/The State Agriculture Ministry Laboratory of Horticultural Plant Growth, Development and Quality Improvement, Zhejiang University, Zijingang Campus, Hangzhou, Zhejiang, People's Republic of China ; Institute of Horticulture, Zhejiang Academy of Agricultural Sciences, Hangzhou, Zhejiang, People's Republic of China.
Hongxia
H
Xu
MOA and Zhejiang Provincial Key Laboratory of Plant Virology, Institute of Virology and Biotechnology, Zhejiang Academy of Agricultural Sciences, Hangzhou, Zhejiang, People's Republic of China.
Yong
Y
Yang
MOA and Zhejiang Provincial Key Laboratory of Plant Virology, Institute of Virology and Biotechnology, Zhejiang Academy of Agricultural Sciences, Hangzhou, Zhejiang, People's Republic of China.
Li
L
Xie
Institute of Horticulture, Zhejiang Academy of Agricultural Sciences, Hangzhou, Zhejiang, People's Republic of China.
Xiaoying
X
Li
Laboratory of Fruit Quality Biology/The State Agriculture Ministry Laboratory of Horticultural Plant Growth, Development and Quality Improvement, Zhejiang University, Zijingang Campus, Hangzhou, Zhejiang, People's Republic of China.
Chao
C
Feng
Institute of Horticulture, Zhejiang Academy of Agricultural Sciences, Hangzhou, Zhejiang, People's Republic of China.
Junwei
J
Chen
Laboratory of Fruit Quality Biology/The State Agriculture Ministry Laboratory of Horticultural Plant Growth, Development and Quality Improvement, Zhejiang University, Zijingang Campus, Hangzhou, Zhejiang, People's Republic of China.
Changjie
C
Xu
D058639:Cold-Shock Response / Q000502:physiology*; D031983:Eriobotrya / Q000502:physiology*; D035264:Flowers / Q000502:physiology; D005615:Freezing; D018506:Gene Expression Regulation, Plant / Q000502:physiology*; D010940:Plant Proteins / Q000096:biosynthesis*; D017382:Reactive Oxygen Species / Q000378:metabolism
D010940:Plant Proteins; D017382:Reactive Oxygen Species; C070556:dehydrin proteins, plant