Waterlogging is one of the main abiotic stresses suffered by plants. Inhibition of aerobic respiration during waterlogging limits energy metabolism and restricts growth and a wide range of developmental processes, from seed germination to vegetative growth and further reproductive growth. Plants respond to waterlogging stress by regulating their morphological structure, energy metabolism, endogenous hormone biosynthesis, and signaling processes. In this updated review, we systematically summarize the changes in morphological structure, photosynthesis, respiration, reactive oxygen species damage, plant hormone synthesis, and signaling cascades after plants were subjected to waterlogging stress. Finally, we propose future challenges and research directions in this field.

Development of adventitious roots (ARs) at the base of the shoot is an important adaptation of plants to waterlogging stress; however, its physiological mechanisms remain unclear. Here, we investigated the regulation of AR formation under waterlogged conditions by hormones and reactive oxygen species (ROS) in Cucumis sativus L., an agriculturally and economically important crop in China. We found that ethylene, auxin, and ROS accumulated in the waterlogged cucumber plants. On the other hand, application of the ethylene receptor inhibitor 1-methylcyclopropene (1-MCP), the auxin transport inhibitor 1-naphthylphthalamic acid (NPA), or the NADPH oxidase inhibitor diphenyleneiodonium (DPI) decreased the number of ARs induced by waterlogging. Auxin enhanced the expression of ethylene biosynthesis genes, which led to ethylene entrapment in waterlogged plants. Both ethylene and auxin induced the generation of ROS. Auxin-induced AR formation was inhibited by 1-MCP, although ethylene-induced AR formation was not inhibited by NPA. Both ethylene-and auxin-induced AR formation were counteracted by DPI.These results indicate that auxin-induced AR formation is dependent on ethylene, whereas ethylene-induced AR formation is independent of auxin. They also show that ROS signals mediate both ethylene-and auxin-induced AR formation in cucumber plants.

BackgroundEggplant (Solanum melongena L.) and turkey berry (S. torvum Sw.), a wild ally of eggplant with promising multi-disease resistance traits, are of great economic, medicinal and genetic importance, but genomic resources for these species are lacking. In the present study, we sequenced the transcriptomes of eggplant and turkey berry to accelerate research on these two non-model species.ResultsWe built comprehensive, high-quality de novo transcriptome assemblies of the two Leptostemonum clade Solanum species from short-read RNA-Sequencing data. We obtained 34,174 unigenes for eggplant and 38,185 unigenes for turkey berry. Functional annotations based on sequence similarity to known plant datasets revealed a distribution of functional categories for both species very similar to that of tomato. Comparison of eggplant, turkey berry and another 11 plant proteomes resulted in 276 high-confidence single-copy orthologous groups, reasonable phylogenetic tree inferences and reliable divergence time estimations. From these data, it appears that eggplant and its wild Leptostemonum clade relative turkey berry split from each other in the late Miocene, ~6.66 million years ago, and that Leptostemonum split from the Potatoe clade in the middle Miocene, ~15.75 million years ago. Furthermore, 621 and 815 plant resistance genes were identified in eggplant and turkey berry respectively, indicating the variation of disease resistance genes between them.ConclusionsThis study provides a comprehensive transcriptome resource for two Leptostemonum clade Solanum species and insight into their evolutionary history and biological characteristics. These resources establish a foundation for further investigations of eggplant biology and for agricultural improvement of this important vegetable. More generally, we show that RNA-Seq is a fast, reliable and cost-effective method for assessing genome evolution in non-model species.Electronic supplementary materialThe online version of this article (doi: 10.1186/1471-2164-15-412) contains supplementary material, which is available to authorized users.

Calcium-dependent protein kinases (CDPKs) are multi-functional proteins that combine calcium-binding and signaling capabilities within a single gene product. Current studies have shown that the CDPKs regulate numerous growth and developmental processes and biotic and abiotic stress responses. Nonetheless, knowledge concerning the specific expression patterns and evolutionary history of the CDPK family in cucumber (Cucumis sativus L.) remains very limited. We, therefore, investigated the phylogenetic relationships and expression profiles of the 19 CDPK genes identified in the cucumber genome sequence, resolving them into four subfamilies based on a phylogenetic tree and gene structures. Tissue-specific expression profiles suggest that cucumber CDPK genes are involved in cucumber tissue development. An expression analysis based on qRT-PCR indicated that cucumber CDPK genes are extensively involved in abscisic acid, salt, cold, drought, heat, and waterlogging responses, possibly by different mechanisms. The fates of two paralogs after divergence were also investigated, suggesting subfunctionalization and neofunctionalization during evolution. These observations lay an important foundation for functional and evolutionary analyses of the CDPK gene family in cucurbitaceae species.

Lotus root is a popular wetland vegetable which produces edible rhizome. At the molecular level, the regulation of rhizome formation is very complex, which has not been sufficiently addressed in research. In this study, to identify differentially expressed genes (DEGs) in lotus root, four libraries (L1 library: stolon stage, L2 library: initial swelling stage, L3 library: middle swelling stage, L4: later swelling stage) were constructed from the rhizome development stages. High-throughput tag-sequencing technique was used which is based on Solexa Genome Analyzer Platform. Approximately 5.0 million tags were sequenced, and 4542104, 4474755, 4777919, and 4750348 clean tags including 151282, 137476, 215872, and 166005 distinct tags were obtained after removal of low quality tags from each library respectively. More than 43% distinct tags were unambiguous tags mapping to the reference genes, and 40% were unambiguous tag-mapped genes. From L1, L2, L3, and L4, total 20471, 18785, 23448, and 21778 genes were annotated, after mapping their functions in existing databases. Profiling of gene expression in L1/L2, L2/L3, and L3/L4 libraries were different among most of the selected 20 DEGs. Most of the DEGs in L1/L2 libraries were relevant to fiber development and stress response, while in L2/L3 and L3/L4 libraries, major of the DEGs were involved in metabolism of energy and storage. All up-regulated transcriptional factors in four libraries and 14 important rhizome formation-related genes in four libraries were also identified. In addition, the expression of 9 genes from identified DEGs was performed by qRT-PCR method. In a summary, this study provides a comprehensive understanding of gene expression during the rhizome formation in lotus root.