Construction of chimeric inducible promoters by elicitors of rice fungal blast pathogen and their expression in transgenic rice

The promoter fragments of wheatGstA1 and potatoGst1 have been amplified by PCR, cloned and fused respectively to the minimal promoter sequence of rice actin gene (Act1)) and its 5′ untranslated leader sequence together withGUS. The constructs with 2 chimeric promoters (WGA and PGA) have been transferred into rice in order to analyze their inducibility patterns in transgenic rice plants. The results show that: WGA and PGA are both inducible by elicitors ofPyricularia oryzae in transgenic rice cells; the intron I of riceAct1 gene is important for the heterogenic expression of monocot and dicot promoter elements in rice; and theAct1 minimal promoter and its 5′ untranslated leader sequence produced low level background expression in rice.     

An intron with a constitutive transport element is retained in a Tap messenger RNA

Alternative splicing is a key factor contributing to genetic diversity and evolution. Intron retention, one form of alternative splicing, is common in plants but rare in higher eukaryotes, because messenger RNAs with retained introns are subject to cellular restriction at the level of cytoplasmic export and expression. Often, retention of internal introns restricts the export of these mRNAs and makes them the targets for degradation by the cellular nonsense-mediated decay machinery if they contain premature stop codons. In fact, many of the database entries for complementary DNAs with retained introns represent them as artefacts that would not affect the proteome. Retroviruses are important model systems in studies of regulation of RNAs with retained introns, because their genomic and mRNAs contain one or more unspliced introns. For example, Mason-Pfizer monkey virus overcomes cellular restrictions by using a cis-acting RNA element known as the constitutive transport element (CTE). The CTE interacts directly with the Tap protein (also known as nuclear RNA export factor 1, encoded by NXF1), which is thought to be a principal export receptor for cellular mRNA, leading to the hypothesis that cellular mRNAs with retained introns use cellular CTE equivalents to overcome restrictions to their expression. Here we show that the Tap gene contains a functional CTE in its alternatively spliced intron 10. Tap mRNA containing this intron is exported to the cytoplasm and is present in polyribosomes. A small Tap protein is encoded by this mRNA and can be detected in human and monkey cells. Our results indicate that Tap regulates expression of its own intron-containing RNA through a CTE-mediated mechanism. Thus, CTEs are likely to be important elements that facilitate efficient expression of mammalian mRNAs with retained introns.     

Molecular cloning, in vitro expression and enzyme activity analysis of violaxanthin de-epoxidase from Oryza sauva L.

The violaxanthin de-epoxidase gene was cloned from rice (Oryza sauva subsp japonica). The full length of the cDNA is 1887 bp, encoding a 446-amino acids protein with the transit peptide of 98 amino acids. The bacterial expression vector pET-Rvde was constructed and the expression quantity of the exogenous protein increased with the induction time by 0.4 mmol/L IPTG. Its molecular weight was similar with that of the native VDE. Western blotting indicated that the expressed protein has immunological reaction with the VDE polyclonal antibody. The absorbance spectrum together with xanthophyll pigments quantification by HPLC demonstrated that the expressed VDE has its enzyme activity, which can de-epoxidate violaxanthin into antheraxanthin and zeaxanthin in vitro.     

Introducing antisense <Emphasis Type="Italic">waxy</Emphasis> gene into rice seeds reduces grain amylose contents using a safe transgenic technique

Rice (Oryza sativa L.) eating quality is one of themost important traits. Amylose content (AC) in rice en-dosperm is a major index affecting rice eating quality[1,2].It has a negative correlation with gel consistency of rice[3].Based on amylose content, r…     

C1 SnoRNA，水稻中一种新的核仁小分子RNA

通过计算机分析国际分子生物学数据库和ｃＤＮＡ序列分析等方法，在水稻（Ｏｒｙｚａｓａｔｉｖａ）中发现了一种新的核仁小分子ＲＮＡ：Ｃ１ＳｎｏＲＮＡ．该ＲＮＡ具有ｂｏｘＣ，ｂｏｘＤ和末端碱基配对区等典型的核仁小分子ＲＮＡ结构特征；并有１４个核苷酸与水稻１８ｓｒＲＮＡ中一段保守序列互补．推测Ｃ１ＳｎｏＲＮＡ可能在１８ｓｒＲＮＡ甲基化过程中起重要作用．编码Ｃ１ＳｎｏＲＮＡ的基因位于水稻Ｈｓｐ７０基因的第一个内含子中．这是在水稻中发现的第一个由基因内含子编码的ＳｎｏＲＮＡ．     

Molecular cloning, chromosomal mapping and expression analysis of disease resistance gene homologues in rice (Oryza sativa L.)

Resistance-like sequences have been amplified from first strand cDNA and genomic DNA of rice by PCR using oligonucleotide primers designed from sequence motifs conserved between resistance genes of tobacco andArabidopsis thaliana. 3 PCR clones, designatedOsr1, Osr2 andOsr3 which were 98% identical in nucleotide sequence level, have been found to be significantly homologous to known plant resistance genes and all contained the conserved motifs of NBS-LRR type resistance genes, such as P-loop, kinase2a, kinase3a and transmembrane domain.Southern hybridization revealed that rice resistance gene hornologueswere organized as a cluster in the genome. RFLP mapping using a DH population derived from anindica/japonka cross (Zhaiyeqing 8/Jingxi 17) and an RFLP linkage map assigned two copies ofOsrl and one copy ofOsr3 to the distal position of chromosome 12 where a blast resistance QTL has been mapped previously. Northern blot analysis showed thatOsrl gene was constitutively transcribed in rice leaves, shoots and roots. Further study concerning isolation of full-length cDNAs would be conducive to elucidating the functions of these genes.     

Cloning and characterization of rice RH3 gene induced by brown planthopper

Histones are basic low molecular weight proteins found in all eukaryotic genomes. The histones include five classes of basic proteins (H1, H2A, H2B, H3 and H4) that interact with each other and nuclear DNA to form the nucleosome. The H3 and H4 histone proteins are highly conserved and form the central tetrameric block of the core-nucleosome. Histone H3 has several post-transcrip- tional modifications such as methylation, acetylation, phosphonation, and ADP-ribosylation and it plays impor…     

Ethylene signaling in rice

Ethylene regulates many aspects of growth, development and responses to environmental stresses in plants. Its signaling pathway has been established in model dicotyledonous plant Arabidopsis. However, its roles and signal transduction in monocotyledous rice plant remain largely unknown. In this review, we summarize the current advances in rice ethylene signaling studies and compare these with the results from Arabidopsis and other plants. Most of the components homologous to those in Arabidopsis ethylene signaling pathway have been found in rice, including five ethylene receptors, OsEIN2, OsEIL1, and OsERFs. Rice ethylene receptors are functionally more divergent than that of Arabidopsis. OsEIN2 and OsEIL1 display limited roles in regulation of rice ethylene responses compared with their Arabidopsis orthologs. ERF-like proteins OsERF1 and OsEBP-89 appear to be involved in rice ethylene signaling. However, whether they are activated through OsEIN2 and OsEIL1-mediated pathway needs further studies. Given that rice uses ethylene to control many processes that do not exist in Arabidopsis, it seems that new components or new mechanisms may exist in rice ethylene signaling pathway.     

The foxtail millet Si69 gene is a Wali7 (wheat aluminum-induced protein 7) homologue and may function in aluminum tolerance

We isolated a clone, named Si69, from a foxtail millet immature seed cDNA library. The protein encoded by Si69 contains a conserved Wali7 (wheat aluminum induced protein 7) domain and shares high-level homology with aluminum-induced proteins from other species including rice and Arabidopsis. The Si69 gene presents as a single locus in foxtail millet genome and is globally expressed in all tissues examined. Its expression is up-regulated by aluminum. The sequence feature and expression pattern suggest that the Si69 gene is involved in aluminum tolerance or detoxification. To confirm its biological functions, Si69 controlled by the CaMV35S promoter was introduced into Arabidopsis. Transgenic plants did not show any visible morphological changes compared to wild-type plants under normal growth conditions. However, when treated with 20 or 50 μmol/L Aluminum (Al), the root apices of wild-type plants were heavily stained by hematoxylin, whereas those of Si69 transgenic plants were not stained when treated with 20 μmol/L Al and slightly stained when treated with 50 μmol/L Al. Scanning electron microscopy (SEM) results further demonstrated that the damage of the root apices was severer in wild-type plants than in transgenic plants. Inhibition of root growth and accumulation of malondialdehyde (MDA), an indicator of lipid peroxidation, were lower in transgenic plants than in wild-type plants. The results show that overexpression of Si69 may increase Al tolerance in transgenic plants, indicating that a series of Wali7-containing genes may play similar roles in Al tolerance/detoxification.