Dec 2011, Volume 5 Issue 4

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    Wenjing LU, Jincai LI, Fangpeng LIU, Juntao GU, Chengjin GUO, Liu XU, Huiyan ZHANG, Kai XIAO

    MicroRNAs (miRNAs) are non-coding small RNAs that regulate gene expression by translational repression or transcript degradation. Thus far, a large number of miRNAs have been identified from model plant species and the quantity of miRNAs has been functionally characterized in diverse plants. However, the molecular characterizations of the conserved miRNAs are still largely elusive in wheat. In this study, 32 wheat miRNAs (TaMIRs) currently released in the Sanger miRBase (the microRNA database) were selected to evaluate the expression patterns under conditions of non-stress (CK) and salt stress treatment. Based on the analysis of semiquantitative RT-PCR and quantitative real qRT-PCR, TaMIR159a, TaMIR160, TaMIR167, TaMIR174, TaMIR399, TaMIR408, TaMIR11124 and TaMIR1133 were found to have responses to salinity stress, with an upregulated pattern under salt stress treatment. Based on a BLAST search against the NCBI GenBank database, the potential targets of the salt-inducible wheat miRNAs were predicted. Except for TaMIR399 not being identified to have the putative target genes, other salt-inducible TaMIRs were found to possess 2 to 7 putative target genes. Together, our results suggest that a subset of miRNAs are involved in the mediation of salt stress signaling responses in wheat via their roles on the regulation of acted target genes at post-transcriptional and translation levels.

    Dan ZHAO, Wei GUO, Weiming SUN, Daqing XU, Daqun LIU

    An enhancin-like gene was cloned from Bacillus thuringiensis (Bt) strain GS8 isolated from soil samples in china. The sequence analysis revealed that an open reading frame (ORF) of 2202 nucleotides encoding a protein containing 733 amino acids with a molecular mass of 84 kDa. The enhancin-like protein showed 100% identity to Bel protein (FJ644935) and 23%–41% identity to viral enhancin proteins; in the 252 to 261 amino-acid sequence of enhancin-like protein, a conserved metal binding motif (HEIAH) similar to that in the reported bacterial enhancin-like proteins was found (HEXXH in viral enhancin protein), which indicated that the enhancin-like protein belongs to metalloprotease. The purified enhancin-like protein was fed together with Cry9Ea to Spodopera exigua and Trichoplusia ni larvae, but no significant increase in toxicity was observed.

    Jihong XING, Qiaoyun WENG, Helong SI, Jianmin HAN, Jingao DONG

    To map Arabidopsis resistance genes to Botrytis cinerea, Arabidopsis Col-0 ecotype resistant to B. cinerea BC18 isolate and Arabidopsis Ler ecotype susceptible to B. cinerea BC18 isolate were crossed. According to the resistant responses of the F1, BC1 and F2 populations to B. cinerea, we identified two genes, named BC1 and BC2, responsible for the resistance of Arabidopsis Ler ecotype to B. cinerea. Through the method of map-based cloning, BC1 was linked to DNA markers CCR1 and DHS1 on the fourth chromosome of Arabidopsis with genetic distances of 1.2 cM and 1.6 cM for CCR1 and DHS1, respectively, and BC2 was linked to DNA markers CA72/NGA151 and NGA106 on the fifth chromosome with genetic distances of 1.4 cM and 2.4 cM for CA72/NGA151 and NGA106, respectively. Our results are beneficial for chromosome walking so that we can obtain the whole gene sequences, which will facilitate the understanding of their roles and manners of resistance to B. cinerea.

    Yunwei ZHANG, Xiang GAO, Shengfang HAN, Dongmei WANG

    The E3 ubiquitin ligase is a multi-functional protein that performs vital roles, particularly in various stress environment. To further understand the biological significance of E3 ubiquitin ligase gene from wheat (TaE3), total RNA was isolated from wheat leaves and then TaE3 gene was amplified by PCR after reverse transcription. The PCR product was cloned into PMD19-T vector to sequence subsequently. And then the recombinant expression vector (pET30a-GST-TaE3-His) was constructed and transformed into E. coli strain BL21 (DE3). SDS-PAGE analysis showed that the recombinant E. coli could express a proximate 43 kDa protein. TaE3 fusion protein was purified by Ni-NTA affinity chromatography from recombinant bacterial lysate and was used to immunize rabbit to produce polyclonal antibody. The titer and specificity of the anti-TaE3 antibody were successfully detected by indirect ELISA and western blot analysis.

    Ghulam ABBAS, Tariq MANZOOR KHAN, Jehanzeb FAROOQ, Abid MAHMOOD, Rana Nadeem ABBAS, Wajad NAZEER, Amjad FAROOQ, Zuhair HASNAIN, Muhammad Naeem AKHTAR

    This research was conducted to explore genetic material that can yield better under salt stress conditions. The experiment was laid out using 27 upland cotton genotypes in a RCBD 2 factorial arrangement with two replications. Saline water (NaCl at 20 dS/m) was applied after satisfactory emergence was achieved. The crop was raised to maturity and data relating to yield, fiber quality and ionic traits were recorded. Analysis of variance showed significant variations in the germplasm. Plant height, bolls per plant, boll weight, GOT%, staple length, staple strength, K+ and K+/Na+ ratio under salinity stress showed a highly significant correlation with seed-cotton yield. The highest direct effect on seed-cotton yield per plant was exhibited by bolls per plant and boll weight. The results from the correlation and path coefficient analyses revealed that although the K+/Na+ ratio had a strong positively significant association with seed-cotton yield, its direct effect on the seed-cotton yield was negative and thus selection on the basis of K+/Na+ may not be fruitful. Hence, only indirect selection through bolls per plant and boll weight may be effective in increasing the seed-cotton yield per plant under salinity stress.

    Lifeng ZHANG, Hui ZHOU, Fengju WEI, Ziyi CHENG, Aihua YAN, Dongmei WANG

    Two cDNA libraries for wheat near-isogenic line TcLr19 under Puccinia recondita stress were constructed by using SMART technique and homologous reorganization method. Wheat near-isogenic line TcLr19 was infected with leaf rust race 366, and total RNA was extracted from the leaves after infection for 4, 8, and 12 h. The total RNAs were reverse transcribed to cDNA by using oligo(dT) primer and random primer, respectively. According to the evaluation on quality, the transformation efficiency was about 1.32 × 106 and 1.0 × 106 transformants/3 μg pGADT7-Rec, respectively, and the library titers were up to 2.62 × 108 and 3.51 × 108 pfu/mL, with 93% and 100% recombinant rate, which indicated the high quality of the two libraries for next screening.

    Junyi CHEN, Li XU

    A maize F2 population was first used to construct a genetic linkage map of Chromosome 6 covering 117.6 cM with an average interval of 3.68 cM between adjacent markers. Based on composite interval mapping (CIM), the quantitative trait loci (QTL) for phosphorus absorption efficiency (PAE) and root-related traits was detected in four environments, i.e., Kaixian County under deficient phosphorus (KXDP), Kaixian County under normal phosphorus (KXNP), SUDP1, and SUDP2. QTLs affecting root weight (RW) were detected simultaneously at the dupssr15 locus region (bin 6.06) on Chromosome 6 in the four environments, while QTL affecting taproot length and fiber number was only detected in one or two environments. The result suggested that taproot length and fiber number were more easily affected by the environment than PAE and RW. The alleles originating from 082 increased PAE and RW on Chromosome 6. The QTL on bin 6.06 explained 4%–10% and 4%–8% of the total phenotypic variance of PAE and RW, respectively, and the estimates of the genetic effects presented dominance and overdominance. The QTL for RW in the dupssr15 locus is the minor QTLs environment interactive effects, which should be particularly useful in MAS manipulation of breeding maize.

    Jincai LI, Yongsheng ZHANG, Juntao GU, Chengjin GUO, Shumin WEN, Guiru LIU, Kai XIAO

    The APETALA2 (AP2) domain defines a large family of DNA binding proteins. It has been demonstrated that the AP2 proteins have important functions in the transcriptional regulation of a variety of biologic processes related to growth and development in various responses to drought and other abiotic stresses. In this essay, recent researches on the AP2 transcription factors, such as the molecular characterization, expression patterns in responses to drought and other abiotic stresses, the roles of ABA on drought responding which were mediated by AP2 transcription factors, transcription regulation mechanisms, and the roles of overexpression of AP2 transcription factor on plant drought tolerance, etc. have been overviewed. Deepening the understanding of signaling and the corresponding transduction pathways that are initiated via drought stress stimuli will play crucial roles for providing the theoretical basis for variety breeding with promising drought tolerance in the future.