A vegetative storage protein (VSP) with trypsin inhibitor activity in a deciduous tree, Sapindus mukorassi,was characterized by means of sodium dodecyl sulfate-polyacrylamide gel electrophoresis, Western-blot, immuno-histochemical localization, light- and electro-microscopy, together with analysis of proteinase inhibitor activity of the purified VSP in vitro. There were two proteins with molecular masses of about 23 and 27 kDa in a relatively high content in the bark tissues of terminal branches of S. mukorassi in leafless periods. The proteins decreased markedly during young shoot development, indicating their role in seasonal nitrogen storage. Immuno-histochemical localization with the polyclonal antibodies raised against the 23 kDa protein demonstrated that the 23 kDa protein was the major component of protein inclusions in protein-storing cells. The protein inclusions were identified by protein-specific staining and should correspond to the electron-dense materials in different forms in the vacuoles of phloem parenchyma cells and phloem ray parenchyma cells under an electron microscope. So, the 23 kDa protein was a typical VSP in S. mukorassi. The 23 and 27 kDa proteins shared no immuno-relatedness, whereas the 23 kDa protein was immuno related with the 22 kDa VSP in lychee and possessed trypsin inhibitor activity. The 23 kDa protein may confer dual functions: nitrogen storage and defense.

Liu SB, Wang XC, Shi MJ, Chen YY, Hu ZH, Tian WM (2009) Vegetative storage protein with trypsin inhibitor activity occurs in Sapindus mukorassi, a sapindaceae deciduous tree. J. Integr. Plant Biol. 51(4), 352–359.

A doubled haploid (DH) population, which consists of 120 lines derived from anther culture of a typical indica and japonica hybrid ‘CJ06’/‘TN1’, was used in this study. Ligule lengths of flag leaf were investigated for quantitative trait loci (QTL) mapping using the DH population. Five QTLs (qLL-2, qLL-4, qLL-6, qLL-10 and qLL-12) controlling the ligule length (LL) were detected on chromosomes 2, 4, 6, 10 and 12, with the variances explained 11.4%, 13.6%, 27.8%, 22.1% and 11.0%, respectively. Using four known genes of ZmGL1, ZmGL2, ZmGL3 and ZmGL4 in maize from the MaizeGDB, their homologs in rice were aligned and integrated into the existing simple sequence repeats linkage map by in silico mapping. A ZmLG1 homolog gene, OsLG1 encoding a squamosa promoter binding protein, was located between the markers RM255 and RM280, which is just identical to the interval of qLL-4 on the long arm of chromosome 4. The results are beneficial to dissection of the ligule molecular mechanism and the study of cereal evolution.

Zeng D, Hu J, Dong G, Liu J, Zeng L, Zhang G, Guo L, Zhou Y, Qian Q (2009) Quantitative trait loci mapping of flag-leaf ligule length in rice and alignment with ZmLG1 gene. J. Integr. Plant Biol. 51(4), 360–366.

Agrobacterium-mediated transformation is widely used in transgenic plant engineering and has been proven to be a powerful tool for insertional mutagenesis of the plant genome. The transferred DNA (T-DNA) from Agrobacterium is integrated into the plant genome through illegitimate recombination between the T-DNA and the plant DNA. Contrasting to the canonical insertion, here we report on a locus showing a complex mutation associated with T-DNA insertion at the BRI1 gene in Arabidopsis thaliana. We obtained a mutant line, named salade for its phenotype of dwarf stature and proliferating rosette.Molecular characterization of thismutant revealed that in addition to T-DNA a non-T-DNA-localized transposon from bacteria was inserted in the Arabidopsis genome and that a region of more than 11.5 kb of the Arabidopsis genome was deleted at the insertion site. The deleted region contains the brassinosteroid receptor gene BRI1 and the transcription factor gene WRKY13. Our finding reveals non-canonical T-DNA insertion, implicating horizontal gene transfer and cautioning the use of T-DNA as mutagen in transgenic research.
 

Zhao Z, Zhu Y, Erhardt M, Ruan Y, Shen WH (2009) A non-canonical transferred DNA insertion at the BRI1 locus in Arabidopsis thaliana.  J. Integr. Plant Biol. 51(4), 367–373.

Interactions between an isolate of dark septate endophytes (DSE) and roots of Dendrobium nobile Lindl. seedlings are reported in this paper. The isolate was obtained from orchid mycorrhizas on Dendrobium sp. in subtropical forest. The fungus formed typical orchid mycorrhiza in aseptic co culture with D. nobile seedlings on modifiedMurashige-Skoog (MMS) medium. Anatomic observations of the infected roots showed that the DSE hyphae invaded the velamen layer, passed through passage cells in exodermis, entered the cortex cells, and then formed fungal pelotons of orchid mycorrhiza. D. nobile seedlings’ plant height, stem diameter, new roots number and biomass were greatly enhanced by inoculating the fungus to seedlings. The fungus was identified as Leptodontidium by sequencing the polymerase chain reaction-amplified rDNA ITS1-5.8S-ITS2 (internal transcribed spacer (ITS)) regions and comparison with similar taxa.

Hou XQ, Guo SX (2009) Interaction between a dark septate endophytic isolate from Dendrobium sp. and roots of D. nobile seedlings. J. Integr. Plant Biol. 51(4), 374–381.

Phosphate (Pi) deficiency causes dramatic root system architecture (RSA changes in higher plants. Here we report that overexpression of HRS1 leads to enhanced sensitivity to low Pi-elicited inhibition of primary root growth in Arabidopsis thaliana seedlings. Bioinformatic investigations uncovered that HRS1 and its six homologs encode putative G2-like transcription factors in Arabidopsis. Analysis of promoter::GUS reporter lines revealed that HRS1 transcripts were present mainly in the root hair region and root hair cells under Pi-sufficient conditions. Pi deprivation increased HRS1 expression level and expanded its expression domain. Although HRS1 knockout mutant did not differ from wild type (WT) control irrespective of Pi status, its overexpression lines were significantly more susceptible to low Pi-elicited primary root shortening. In both WT and HRS1 overexpression seedlings, low Pi-induced primary root shortening was accompanied by enhanced root hair cell differentiation, but this enhancement occurred to a greater extent in the latter genotype. Collectively, our data suggest that HRS1 may be involved in the modulation of primary root and root hair growth in Pi-deprived Arabidopsis seedlings, and provide useful clues for further research into the function of HRS1 and its homologs and the mechanisms behind RSA changes under Pi-deficient conditions.

Liu H, Yang H, Wu C, Feng J, Liu X, Qin H, Wang D (2009) Overexpressing HRS1 confers hypersensitivity to low phosphate-elicited inhibition of primary root growth in Arabidopsis thaliana. J. Integr. Plant Biol. 51(4), 382–392.

A set of 148 F₉ recombinant inbred lines (RILs) was developed from the cross of an indica cultivar 93-11 and japonica cultivar DT713, showing strong F1 heterosis. Subsequently, two backcross F₁ (BCF₁) populations were constructed by backcrossing these 148 RILs to two parents, 93-11 and DT713. These three related populations (281BCF₁ lines, 148 RILs) were phenotyped for six yield-related traits in two locations. Significant inbreeding depression was detected in the population of RILS and a high level of heterosis was observed in the two BCF₁ populations. A total of 42 main-effect quantitative trait loci (M-QTLs) and 109 epistatic effect QTL pairs (E-QTLs) were detected in the three related populations using the mixed model approach. By comparing the genetic effects of these QTLs detected in the RILs, BCF₁ performance and mid parental heterosis (H_MP), we found that, in both BCF₁ populations, the QTLs detected could be classified into two predominant types: additive and over dominant loci, which indicated that the additive and over-dominant effect were more important than complete or partially dominance for M-QTLs and E-QTLs. Further, we found that the E-QTLs detected collectively explained a larger portion of the total phenotypic variation than the M-QTLs in both RILs and BCF₁ populations. All of these results suggest that additive and over dominance resulting from epistatic loci might be the primary genetic basis of heterosis in rice.

Luo XJ, Fu YC, Zhang PJ, Wu S, Tian F, Liu JY, Zhu ZF, Yang JS, Sun CQ (2009) Additive and over-dominant effects resulting from epistatic loci are the primary genetic basis of heterosis in rice. J. Integr. Plant Biol. 51(4), 393–408.

Prunus necrotic ring spot virus (PNRSV) and grapevine fanleaf virus (GFLV) were detected by fluoroimmunoassay using bacterial magnetic particles (BMPs), and a double antibody sandwich enzyme linked immunosorbent assay (DAS-ELISA). For the fluoroimmunoassay, fluorescein isothiocyanate labeled anti-PNRSV antibody or anti-GFLV antibody was conjugated onto BMPs of Magnetospirillum gryphiswaldense MSR-1. With this method, a very low minimum antigen concentration (1 × 10⁶ dilution of the original sample concentration) could be detected. Using DAS-ELISA, the minimum antigen detection concentration was the original sample concentration. Thus, comparing these two methods, a BMP-based method could increase the sensitivity up to six orders of magnitude (10⁶) higher than an ELISA-based method of detection PNRSV and GFLV.

Chen JF, Li Y, Wang ZF, Li JL, Jiang W, Li SH (2009) High-sensitivity detection of fruit tree viruses using bacterial magnetic particles. J. Integr. Plant Biol. 51(4), 409–413.

A limnological study was carried out to determine the responses of superoxide dismutase (SOD) activities and soluble protein (SP) contents of 11 common aquatic plants to eutrophication stress. Field investigation in 12 lakes in the middle and lower reaches of the Yangtze River was carried out from March to September 2004. Our results indicated that nonsubmersed (emergent and floating-leafed) plants and submersed plants showed different responses to eutrophication stress. Both SOD activities of the non-submersed and submersed plants were negatively correlated with their SP contents (P < 0.000 1). SP contents of non-submersed plants were significantly correlated with all nitrogen variables in the water (P < 0.05), whereas SP contents of submersed plants were only significantly correlated with carbon variables as well as ammonium and Secchi depth (SD) in water (P < 0.05). Only SOD activities of submersed plants were decreased with decline of SD in water (P < 0.001). Our results indicate that the decline of SOD activities of submersed plants were mainly caused by light limitation, this showed a coincidence with the decline of macrophytes in eutrophic lakes, which might imply that the antioxidant system of the submersed plants were impaired under eutrophication stress.

Wu AP, Cao T, Wu SK, Ni LY, Xie P (2009) Trends of superoxide dismutase and soluble protein of aquatic plants in lakes of different trophic levels in the middle and lower reaches of the Yangtze River, China. J. Integr. Plant Biol. 51(4), 414–422.

The frequency and distribution of the major vernalization requirement genes and their effects on growth habits were studied. Of the 551 bread wheat genotypes tested, seven allelic combinations of the three Vrn-1 genes were found to be responsible for the spring habit, three for the facultative habit and one for the winter habit. The three Vrn-1 genes behaved additively with the dominant allele of Vrn-A1 exerting the strongest effect. The allele combinations of the facultative genotypes and the discovery of spring genotypes with “winter” allele of Vrn-1 implied the presence of as yet unidentified alleles/genes for vernalization response. The dominant alleles of the three Vrn-1 genes were found in all ten ecological regions where wheat is cultivated in China, with Vrn-D1 as the most common allele in nine and Vrn-A1 in one. The combination of vrn-A1vrn- B1Vrn-D1 was the predominant genotype in seven of the regions. Compared with landraces, improved varieties contain a higher proportion of the spring type. This was attributed by a higher frequency of the dominant Vrn-A1 and Vrn-B1 alleles in the latter. Correlations between Vrn-1 allelic constitutions and heading date, spike length, plant type as well as cold tolerance were established.

Sun QM, Zhou RH, Gao LF, Zhao GY, Jia JZ (2009) The characterization and geographical distribution of the genes responsible for vernalization requirement in Chinese bread wheat. J. Integr. Plant Biol. 51(4), 423–432.