Construction And Analysis Of Full Length CDNA Library In Sorghum And Functional Characterization Of ZmBIP In Maize

As a C4plant of Gramineae, sorghum had high photosynthetic efficiency and high water useefficiency. It grows in high temperature-and drought-prone areas and is a typical drought resistant crop.Full-length cDNA library includes a number of genes with intact open reading frame (ORF) and is animportant method to capture gene sequence on a large scale.1. RNAs from five tissues of sorghum under abiotic stresses including drought were extracted andan improved Oligo-capping method was used to construct drought stress response related normalizedfull-length cDNA library. The library capacity was2.24×106cfu and the average size of insertedsequences was up to1kb with a recombination ratio of93%.2. Ten thousands of clones were sequenced from5' end and4337unigenes were identified byassembly. Bioinformatic analysis of the unigenes were conducted, such as gene ontology analysis,transcription factor analysis, KEGG signal pathway analysis and genome mapping. The gene ontologyanalysis showed that, in these unigenes152genes responded to stimulus,50genes had antioxidantactivity,193genes had nucleic acid binding transcription factor activities and67genes had electroncarrier activities. These genes might be concerned with plant pathways responded to drought stress.Compared with the amino acid sequences of plant transcription factor database,351transcription factorswere identified. Among them,6.8%belonged to ERF family, and WRKY family, MYB_related andNAC family accounted for5.9%,5.1%,4.8%, respectively. KEGG signal pathway analysis showed thatphosphoenolpyruvate carboxylase (PPC), pyruvate phosphote dikinase (PPDK) of carbon fixationpathway in photosynthetic organs and peroxisome (PEX1, PEX5, PEX6, etc.) were involved.93.87%ofthe4337full-length cDNAs were mapped on the sorghum genome. In addition,3841sequences weremapped to single locus on the genome. The results showed that single cope genes accounted for a largeportion of sorghum.3. Full-length cDNA overexpressing system (FOX system) was used to identify the gene functionof full-length cDNA library. Sorghum FOX system were constructed and positive transgenicArabidopsis plants were confirmed by molecular detection.4. Two genes of the BIP family in maize "Han21" line were identified. The quantitative RT-PCRanalysis indicated that ZmBIP1and ZmBIP2were down-regulated by mannitol. Overexpression ofZmBIP1and ZmBIP2respectively in Arabidopsis led to sensitivities to salt and mannitol stresses in seedgermination period. Moreover, Overexpression of ZmBIP2in Arabidopsis resulted in salt sensitivityduring the reproductive growth stage. The results suggested that ZmBIP1and ZmBIP2maight benegative regulators in stress signaling pathways.