植物生理与分子生物学学报最新文献

'Tsuda' turnip (Brassica campestris L. ssp. rapa), in which roots anthocyanin pigmentation is light-sensitive, was used as the material. 'Tsuda' plants were held in darkness or irradiated with sun light and constant light for different time. Anthocyanins in root peel of 'Tsuda' turnip exposed to constant light were identified and quantified with a UV-visual spectrophotometer. The results demonstrated that the anthocyanins accumulation in 'Tsuda' was related with light-exposure time (Fig.1 and Table 1). Fragments of genes selected from the subtraction library of 'Tsuda' turnip involved in anthocyanin biosynthesis were used as probes. The Northern blotting results showed that the expression of PAL, CHS, F3H, DFR and ANS could be induced by irradiation with light and the expression of these genes was related with light exposure time. The expression of MYB was basically the same whether in darkness or in light (Figs.2,3).

The role of serine endopeptidase in cucumber leaf senescence was studied by using the inhibitor of serine endopeptidase and plant growth regulators (6-BA and ABA) on darkness-induced cucumber leaves. The results showed that the senescence of cucumber leaves were delayed by AEBSF [4-(2-aminoethyl) benzenesulfonyl fluoride hydrochloride], an inhibitor of serine-type endopeptidase, or 6-BA treatment. The chlorophyll contents increased by AEBSF (Fig.3) and the protein degradation of leaves under AEBSF treatment declined more slowly than in the control or under ABA 50 micromol/L treatment (Fig.4), partly because the activities of serine endopeptidases became lower during senescence. However, the activities of endopeptidase in cucumber leaf were increased by ABA 50 micromol/L (Fig.2A), furthermore, the MDA content were also influenced by AEBSF and plant growth regulators (Fig.5). Native gradient PAGE showed that six bands of isoenzymes were detected in cucumber leaves and four bands of which were the type of serine-endopeptidase (Fig.1), and proved that the activities of serine-endopeptidase were inhibited by AEBSF, but enhanced by ABA (Fig.2B) in the leaves. It implies that serine endopeptidases might play an important role in cucumber leaf senescence.

Possible regulation of salt stress-induced ABA accumulation by nitric oxide (NO) in maize seedling was investigated. Both NO and ABA contents of maize leaves and root tips were increased in response to salt stress (Fig.1,2). Similar to the effects of salt stress, ABA contents of maize leaves and root tips were increased after the treatment of maize leaves with sodium nitroprusside (SNP, a nitric oxide donor) alone (Fig.3). Compared to the salt stress-induced ABA accumulation, this SNP-induced ABA increase was much faster, suggesting that NO may be an intermediate signal from salt stress to ABA accumulation. When NO production inhibitors L-NAME and NaN(3) treatments were applied, salt stress-induced ABA accumulation was lowered (Fig.4). Treatment with NO scavenger cPTIO also inhibited the salt stress-induced ABA increase (Fig.5). From these results it is deduced that NO is involved in regulation of ABA accumulation under salt stress.

A glycoprotein elicitor, CSBI, isolated from hyphal cell walls of the strain 97-151a of M. grisea race ZC(13) was purified by centrifugation, ultra-filtration, gel filtration and anion exchange chromatography (Fig.1). CSBI appeared as a single band on silver-stained SDS-PAGE (Fig.2). Anthrone-colorimetric assay and Coomassie blue G-250 staining showed that the carbohydrate-to-protein ratio was 9.32 (Table 1). The induction of peroxidase activity in incompatible interactions was stronger than in compatible interactions (P<0.05) after treatment with CSBI on rice leaves (Fig.3). The N-terminal sequence of CSBI was determined to be ITPEAMLSANCCSD, which showed high homology to a 78.671-kD hypothetical protein MG07877.4 (accession No. gi38107424) from M. grisea in NCBI databases. CSBI was either identified as hypothetical protein MG07877.4 by matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS) with 9 matching peptides (Fig.4, Table 2).

Seedlings of a hypoxia-resistant cultivar, Lübachun No.4, and a hypoxia-sensitive cultivar, Zhongnong No.8, were applied by feeding roots. The effects of exogenous 24-epibrassinolide (EBR) on lipid peroxidation, activities of major antioxidant enzymes and anaerobic respiratory enzymes and their time courses were investigated in cucumber seedling roots under hypoxia stress. Root growth was significantly inhibited under hypoxia stress, which was improved by exogenous EBR application (Figs.1,2). O(-*)(2) and H(2)O(2) level and lipid peroxidation were significantly increased in the roots upon exposure to hypoxia stress, which were inhibited by exogenous EBR application (Fig.3). EBR treatment increased SOD and POD activities under hypoxia stress (Fig.4). Hypoxia enhanced the activities of lactate dehydrogenase (LDH), alcohol dehydrogenase (ADH) and pyruvate decarboxylase (PDC) whereas EBR treatment significantly increased ADH activity, but decreased LDH activity (Fig.5). There was no significant difference in CAT and PDC activities between the hypoxia stress treatment and "hypoxia+EBR" treatment (Fig.4,5). From the results obtained in this work it can be concluded that oxidative damage on seedling roots by hypoxia stress can be considerably alleviated, and alcohol fermentation can be enhanced by EBR treatment.

Plant aquaporins, belonging to the MIP superfamily, are a series of transmembrane proteins that facilitate water transport through cell membranes. In this study, a cDNA clone encoding the PIP1-like protein was isolated from cotton (Gossypium hirsutum) cDNA libraries, and designated as GhAQP1 (Fig.1). We also isolated the GhAQP1 gene from cotton genome by PCR. The gene is 2,096 bp in length, including an open reading frame (ORF) and 5'-/3'-untranslated regions (UTR). It contains two introns in its ORF. The first intron is inserted between codons 209 and 210 in the fifth transmembrane helix, and another is located between codons 256 and 257 in the sixth transmembrane helix of GhAQP1, respectively (Figs.2 and 3). Northern blot analysis showed that GhAQP1 gene is expressed specifically in 6-15 DPA ovule, and reaches a peak in 9 DPA ovule (Figs.4 and 5), suggesting that its expression is ovule-specific and developmentally regulated in cotton.

To investigate the changes in mitochondrial permeability transition, DNA degradation and cell death, seedling roots of Malus hupehensis Rehd. were treated directly with exogenous H(2)O(2). The results showed that mitochondrial permeability increased obviously by 0.024% (V/V) H(2)O(2) treatment for 30 min and increased continuously during the time of H(2)O(2) treatment (Fig.1). At the time of mitochondrial permeability increasing, mitochondrial membrane potential (Delta psi m) decreased (Fig.2). In addition, the ratio of Cyt c/a became lower (Fig.3) when mitochondrial permeability increased and Delta psi m decreased. DNA fragments were detected at the 60 min of H(2)O(2) treatment, the number of fragments increased after 60 min of H(2)O(2) treatment (Fig.4). Granular nuclei stained irregularly were evident in root slices stained by acridine orange (Fig.5). This indicates H(2)O(2) can induce programmed cell death by increasing mitochondrial permeability and decreasing Delta psi m in the root of Malus hupehensis Rehd.

A rice male-sterile mutant msp1-4 (MULTIPLE SPOROCYTE) with japonica cultivar '9522' background, was obtained in M(3) population treated with (60)Co gamma-ray. Results of genetic analysis indicated that the male-sterile phenotype was controlled by a single recessive locus. To map this locus, an F(2) population was constructed from the cross between the msp1-4 (japonica) and 'LongTeFu B' (indica). This locus was mapped between the two InDel markers, WY-4 and WY-8, with physical distance of 247 kb. A deletion with 10 base pairs between 758 bp and 767 bp in MSP1 open reading frame was confirmed by sequence analysis, which led to pre-termination of MSP1 translation. Phenotype analysis of msp1-4 indicated that it was similar to the msp1 mutant. To insight the expression change of rice anther developmental genes in this mutant, semi-quantitative RT-PCR analysis was carried out. The results showed that the expression level of rice UDT1 and GAMYB were reduced in msp1-4, implying that UDT1 and GAMYB are possibly the downstream genes of MSP1 gene in rice pollen development.

Maize nonspecific lipid transfer protein (Zm-nsLTP) was cloned and expressed to investigate its CaM-binding activity. The cDNA of Zm-nsLTP was amplified using RT-PCR (Fig.1), and then inserted into the vector pET32a(+). The recombinant vector pET-Zm-nsLTP was expressed in E. coli BL21(DE3)trxB(-). Results of CaM-gel overlay assays (Fig.2) and CaM-sepharose pull-down experiments (Fig.3) indicated that recombinant Zm-nsLTP was bound to CaM in a Ca(2+)-independent manner, which is in accordance with the way that CaMBP-10 and Arabidopsis non-specific lipid transfer protein-1 (At-nsLTP1) are bound to CaM. The CaM-binding domain in Zm-nsLTP was mapped to the region of 47-60 amino acids (Fig.3), and online sequence analysis using Predict Protein program predicted that it has a BAA structure (Fig.4,5).