Comparative proteomic analysis of rd29A:RdreB1BI transgenic and non-transgenic strawberries exposed to low temperature

Combined transcriptomic and proteomic analysis reveals multiple pathways involved in self-pollen tube development and the potential roles of FviYABBY1 in self-incompatibility in Fragaria viridis

Fragaria viridis exhibits S-RNase-based gametophytic self-incompatibility, in which S-RNase is the major factor inhibiting pollen tube growth. However, the pathways involved in and the immediate causes of the inhibition of pollen tube growth remain unknown. Here, interactive RNA sequencing and proteome analysis revealed changes in the transcriptomic and proteomic profiles of F. viridis styles harvested at 0 and 24 h after self-pollination. A total of 2,181 differentially expressed genes and 200 differentially abundant proteins were identified during the pollen development stage of self-pollination. Differentially expressed genes and differentially abundant proteins associated with self-incompatible pollination were further mined, and multiple pathways were found to be involved. Interestingly, the expression pattern of the transcription factor FviYABBY1, which is linked to polar growth, differed from those of other genes within the same family. Specifically, FviYABBY1 expression was extremely high in pollen, and its expression trend in self-pollinated styles was consistent with that of S-RNase. Furthermore, FviYABBY1 interacted with S-RNase in a non-S haplotype way. Therefore, FviYABBY1 affects the expression of polar growth-related genes in self-pollen tubes and is positively regulated by S-RNase.

Characterization of PcLEA14, a Group 5 Late Embryogenesis Abundant Protein Gene from Pear (Pyrus communis)

Fruit trees need to overcome harsh winter climates to ensure perennially; therefore, they are strongly influenced by environmental stress. In the present study, we focused on the pear homolog PcLEA14 belonging to the unique 5C late embryogenesis abundant (LEA) protein group for which information is limited on fruit trees. PcLEA14 was confirmed to belong to this protein group using phylogenetic tree analysis, and its expression was induced by low-temperature stress. The seasonal fluctuation in its expression was considered to be related to its role in enduring overwinter temperatures, which is particularly important in perennially. Moreover, the function of PcLEA14 in low-temperature stress tolerance was revealed in transgenic Arabidopsis. Subsequently, the pear homolog of dehydration-responsive element-binding protein/C-repeat binding factor1 (DREB1), which is an important transcription factor in low-temperature stress tolerance and is uncharacterized in pear, was analyzed after bioinformatics analysis revealed the presence of DREB cis-regulatory elements in PcLEA14 and the dormancy-related gene, both of which are also expressed during low temperatures. Among the five PcDREBs, PcDREB1A and PcDREB1C exhibited similar expression patterns to PcLEA14 whereas the other PcDREBs were not expressed in winter, suggesting their different physiological roles. Our findings suggest that the low-temperature tolerance mechanism in overwintering trees is associated with group 5C LEA proteins and DREB1.

The Comparatively Proteomic Analysis in Response to Cold Stress in Cassava Plantlets

Cassava (Manihot esculenta Crantz) is a tropical root crop and sensitive to low temperature. However, it is poorly to know how cassava can modify its metabolism and growth to adapt to cold stress. An investigation aimed at a better understanding of cold-tolerant mechanism of cassava plantlets was carried out with the approaches of physiology and proteomics in the present study. The principal component analysis of seven physiological characteristics showed that electrolyte leakage (EL), chlorophyll content, and malondialdehyde (MDA) may be the most important physiological indexes for determining cold-resistant abilities of cassava. The genome-wide proteomic analysis showed that 20 differential proteins had the same patterns in the apical expanded leaves of cassava SC8 and Col1046. They were mainly related to photosynthesis, carbon metabolism and energy metabolism, defense, protein synthesis, amino acid metabolism, signal transduction, structure, detoxifying and antioxidant, chaperones, and DNA-binding proteins, in which 40 % were related with photosynthesis. The remarkable variation in photosynthetic activity and expression level of peroxiredoxin is closely linked with expression levels of proteomic profiles. Moreover, analysis of differentially expressed proteins under cold stress is an important step toward further elucidation of mechanisms of cold stress resistance.

Comparative proteomic analysis of floral color variegation in peach

Variegation in flower is a special trait in ornamental peach (Prunus persica L.). To investigate the mechanism of color variegation, we used a combination of two dimensional gel electrophoresis and mass spectrometry to explore the proteomic profiles between variegated flower (VF) and red flower (RF) buds of the peach cultivar 'Sahong Tao'. More than 500 highly reproducible protein spots (P < 0.05) were detected and 72 protein spots showed a greater than two-fold difference in their values. We identified 70 proteins that may play roles in petal coloration. The mRNA levels of the corresponding genes were detected using quantitative RT-PCR. The results show that most of the proteins are involved in energy and metabolism, which provide energy and substrates. We found that LDOX, WD40, ACC, and PPO II are related to the pigment biosynthetic pathway. The activity of PPO enzyme was further validated and showed the higher with significant differences in RF compared with the VF ones. Moreover, the four UCH proteins are involved in protein fate and may be important in post-translational modifications in peach flowers. Our study is the first comparative proteomic analysis of floral variegation and will contribute to further investigations into the molecular mechanism of flower petal coloration in ornamental peach.

Transcription factors and anthocyanin genes related to low-temperature tolerance in rd29A:RdreB1BI transgenic strawberry

Dehydration-responsive element-binding (DREB) transcription factors play critical roles in plant stress responses and signal transduction. To further understand how DREB regulates genes expression to promote cold-hardiness, Illumina/Solexa sequencing technology was used to compare the transcriptomes of non-transgenic and rd29A:RdreB1BI transgenic strawberry plants exposed to low temperatures. Approximately 3.5 million sequence tags were obtained from non-transgenic (NT) and transgenic (T) strawberry untreated (C) or low-temperature treated (LT) leaf samples. Over 1000 genes were differentially expressed between the NT-C and T-C plants, and also the NT-C and NT-LT, as well as the T-C and T-LT plants. Analysis of the genes up-regulated following low-temperature treatment revealed that the majority are linked to metabolism, biosynthesis, transcription and signal transduction. Uniquely up-regulated transcription factors as well as anthocyanin biosynthetic pathway genes are discussed. Accumulation of anthocyanin in the stolon and the base of the petiole differed between non-treated NT and T plants, and this correlated with gene expression patterns. The differentially expressed genes that encode transcription factors and anthocyanin enzymes may contribute to the cold hardiness of RdreB1BI transgenic strawberry. The transcriptome data provide a valuable resource for further studies of strawberry growth and development and DREB-mediated gene regulation under low-temperature stress.

Proteomic analyses reveal differences in cold acclimation mechanisms in freezing-tolerant and freezing-sensitive cultivars of alfalfa

Cold acclimation in alfalfa (Medicago sativa L.) plays a crucial role in cold tolerance to harsh winters. To examine the cold acclimation mechanisms in freezing-tolerant alfalfa (ZD) and freezing-sensitive alfalfa (W5), holoproteins, and low-abundance proteins (after the removal of RuBisCO) from leaves were extracted to analyze differences at the protein level. A total of 84 spots were selected, and 67 spots were identified. Of these, the abundance of 49 spots and 24 spots in ZD and W5, respectively, were altered during adaptation to chilling stress. Proteomic results revealed that proteins involved in photosynthesis, protein metabolism, energy metabolism, stress and redox and other proteins were mobilized in adaptation to chilling stress. In ZD, a greater number of changes were observed in proteins, and autologous metabolism and biosynthesis were slowed in response to chilling stress, thereby reducing consumption, allowing for homeostasis. The capability for protein folding and protein biosynthesis in W5 was enhanced, which allows protection against chilling stress. The ability to perceive low temperatures was more sensitive in freezing-tolerant alfalfa compared to freezing-sensitive alfalfa. This proteomics study provides new insights into the cold acclimation mechanism in alfalfa.