植物生理与分子生物学学报最新文献

In two mung bean cultivars (Phaseolus raditus L. cv. 'Qindou-20' and 'Zhonglv-1') with different sensitivities to UV-B grown in growth chamber under supplemental or no supplemental UV-B radiation (0.4 W/m(2)) with or without 0.4% NaCl, the effects of NaCl stress on UV-B-induced DNA damage and repair were studied. The results showed that, under NaCl stress, (i) CPD accumulation was lower in the tolerant cultivar 'Zhonglv-1' but was the same in the sensitive cultivar 'Qindou-20', (ii) CPD formation in both cultivars was weakened, (iii) the photorepair and dark repair capacity were higher in the tolerant cultivar and (iv) the photorepair was weakened and dark repair capacity did not change in the sensitive cultivar. There was a negative correlation between susceptibility of CPD formation and levels of UV-absorbing compounds. These results demonstrate that NaCl stress can affect not only the susceptibility to CPD formation, but also the capacities for photorepair and dark repair of DNA, which together result in the change in UV-B-induced CPD accumulation and thereby that in sensitivity of plant to UV-B. The results also suggest that the differences in susceptibilities to CPD formation are due to the differences in levels of UV-absorbing compounds.

Protein translocation channel in endosplasmic reticulum (ER) of eukaryotes is composed of several subunits of Sec61 complex, which is essential for protein secretion. In the present study, we cloned a full-length cDNA fragment of 621 bp coding 107 amino acids from a psychrophile and endangered plant Gymnadenia conopsea, which grows in high land. Sequence analysis revealed that the gene was highly homologous to the member Sec61beta of ER protein transporter channel, which was thus designated as GcSec61beta. Phylogenetic tree shows that the GcSec61beta was closely related to the corresponding genes from Arabidopsis thaliana and Oryza sativa. Results of semi-quantitative RT-PCR showed that the expression of GcSec61beta was high both in leaves and the bud, and also induced by low temperature treatment. The sequence of the GcSec61beta was introduced into pET28a vector and transformed to E. coli strain BL21. The growth of E. coli was slowed down but the cold resistance was increased by the expression of GcSec61beta, which provides a new function of GcSec61beta protein.

The endogenous hormone ABA concentrations increased in the leaves, shoots and roots of sweet potato plants infected with Fusarium solani f. sp. batatas (FSB) or treated by its culture filtrate. The accumulation of ABA occurred firstly in the roots, but the highest concentration was in the shoots. The endogenous GA(1/3) concentration of leaves, shoots and roots of infected sweet potato kept at markedly low levels during the period of experiments.The ABA concentration of sweet potato seedlings increased observably after 9 h treatment with FSB culture filtrate, but decreased significantly after 15 h, and the GA(1/3) concentration increased markedly after 15 h treatment with 10(1), 10(2) dilution of FSB culture filtrate (after 12 h treatment with 10(3) dilution). The disease symptoms may be induced by the changes in concentration of ABA and GA(1/3) in the plants. The root rot-infected sweet potatoes grew upright without tailing, having aerial roots in knots near the ground, and were in full bloom in autumn.

The Arabidopsis semi-dominant mutant upright rosette (uro) was named from its upright-growing leaves. Previous results suggest that uro mutant was caused by a single gene mutation and the URO function might be associated with auxin-mediated plant development. In this paper, some ethylene-related phenotypes of uro mutant are reported, such as hyponastic rosette leaves, persistent off perianth and elongated hypocotyls. Results of ACC and ethylene inhibitor AgNO(3) treatment experiment suggest that some of the phenotypes of uro mutant are caused by ethylene signal system abnormality. uro mutant is an important material for studying the ethylene signal system especially for the relationship between auxin and ethylene.

To clarify the function mechanism of antisense-thioredoxin s (anti-trxs) gene in transgenic wheat, the expression pattern of endogenous trxh gene in transgenic line 01TY70-1-17-5 and non-transgenic cultivar 'Yumai 70' were detected by semi-quantitative RT-PCR using wheat actin gene as the endogenous control. The results of analysis of transgenic and non-transgenic seeds in different maturation periods, different tissues and different germinating processes indicated that the mRNA transcript amounts of trxh gene in transgenic line seed were lowered distinctly, though the trxh gene mRNA transcript level varied greatly in different developing and germination stages. The mRNA transcript amounts of trxh gene in transgenic line seed were significantly lower than the control seeds by 20.1% 15-30 d after anthesis. The lowest mRNA transcript amount of trxh gene appeared at 25 day after fluorescence and the difference was significant at the 0.05 level. The analysis of gene expression in different tissues also indicated that the transcript levels of trxh gene in transgenic seed were significantly lower than control seeds in 25 d and 30 d after anthesis. The lowest amounts of mRNA transcript of trxh gene was from the endosperm 25 d after anthesis followed by embryo and then by whole seed. During seed germination, the mRNA transcript amounts of trxh gene in transgenic seed were lower than control seed after imbibing 24 h, but the difference was not significant. The above result demonstrated that foreign antisense trxs gene directly interferes with the expression of the endogenous gene.

Amplified fragment length polymorphism (AFLP) was used to study 30 individuals from 5 wild populations of Dioscorea zingiberensis for the first time. A total of 14 698 bands were detected with 9 pairs of AFLP primers and 12 686 of them were polymorphic. On the average each primer combination could be used to detect 230 polymorphic bands and account for 85.92% of total genetic diversity at species level. Shannonos index of diversity (I) was 0.3656-/+0.1721, and Nei's gene diversity (H) was 0.2322-/+0.2200 at the species level. The result of genetic variance analysis showed the coefficient of genetic differentiation (Gst) was 0.4827 at species level, it indicated there were certain degree of genetic differentiation in five Dioscorea zingiberensis populations. The gene flow (Nm) among populations of D. zingiberensis was 0.5358. The data were analyzed using unweighted pair group method, basing on arithmetic averages (UPGMA) bootstrap analysis. Cluster analyses were performed by using NTSYSpc version 2.11F and Popgene 1.32 software. The results showed that the genetic differentiation of 5 wild populations of D. zingiberensis was abundant, and 5 wild populations of D. zingiberensis could be clustered by the distance of the position basically. The AFLP molecular marker was used to identify the genetic differences of different populations of Dioscorea zingiberensis.

The effects of nitric oxide (NO) and ethylene on Vicia faba L. stomatal movement were studied. The results showed that NO donor SNP (sodium nitroprusside) 10 micromol/L and ethylene 0.04% could induce stomatal closure distinctly and they could promote stomatal closure when treated together. When treated with AVG (an inhibitor of ethylene synthesis), c-PTIO (a specific scavenger of NO) and NaN(3) (an inhibitor of NR), the effects of NO- and ethylene-induced stomatal closure were inhibited but the inhibitor of nitric oxide synthase (NOS) had little effect. We presumed that there was coordinative effect between NO and ethylene in regulation of stomatal closure; ethylene could induce stomatal closure by regulating the production of nitrate reductase (NR)-dependent NO.

Ion-specific stress effects of Na(+) and Cl(-) on photosynthesis of seedlings of two soybean (Glycine max) cultivars (the salt-tolerant 'Lee68' and the salt-sensitive 'N23674') were studied and compared under isoosmotic (-0.53 MPa) solutions [PEG-6000, NaCl, Na(+) (without Cl(-)) and Cl(-) (without Na(+))] for 6 d. The results showed that the chlorophyll contents and the ribulose bisphosphate carboxylase/oxygenase (Rubisco) activities of seedlings of both cultivars were inhibited to a less degree by PEG-6000 than by NaCl, Na(+) (without Cl(-)) or Cl(-) (without Na(+)) solutions. The maximum photochemical efficiency of photosystem II (PSII) (F(v)/F(m)), electron transfer rate (ETR) and effective quantum yield of PSII photochemistry (F(v)'/F(m)') were lowered significantly by PEG-6000 treatment for 2 d and 6 d. But when treated with the three isoosmotic salt stresses, most of the above three indexes significantly declined. Leaf stomatal conductance (G(s)) and net photosynthetic rate (P(n)) in both cultivars were significantly decreased under the four isoosmotic treatments, and much more drops were observed in the three salt stresses, but the intercellular CO(2) concentration (C(i)) decreased by PEG-6000 treatment and increased by the three salt stresses. Higher decreases including chlorophyll content, Rubisco activity, F(v)/F(m), ETR, F(v)'/F(m)', P(n) and G(s), and higher contents of Cl(-) as well as the content of Cl(-) plus Na(+) in chloroplasts were all observed under Cl(-) (without Na(+)) treatment than those under Na(+) (without Cl(-)) treatment, especially for the salt-sensitive cultivar 'N23674'. The results indicate that, among the adverse effects of NaCl stress on photosynthesis of G. max seedlings, the ionic toxicity was stronger than osmotic stress, and the toxicity of Cl(-) was more severe than that of Na(+).

By simultaneously analyzing chlorophyll a fluorescence transient and light absorbance at 820 nm, and detecting activities of superoxide dismutase (SOD) and ascorbate peroxidase (APX), the effects of chilling stress under weak light on functions of photosystem I (PSI) and photosystem II (PSII) in leaves of a wild type soybean variety 'ZYD00019' and a cultivar soybean variety 'Zaoshu No.1' were investigated. The results showed that the functions of both PSI and PSII were damaged by the chilling stress under weak light. The higher tolerance to chilling stress under weak light in the wild soybean might be due to its higher activities of SOD and APX and its stability and coordination of its PSI and PSII.

Poplar is among the most important deciduous tree species in plantations over the world and has been used as an important model system for molecular genetics of trees. The analysis of codon usage may improve the understanding of the mechanism of codon distribution and variation in poplar and the understanding of factors shaping the codon usage patterns. Here, an EN(c) (effective number of codons)-plot method and multivariate statistical method called correspondence analysis (COA) were used to examine the codon usage of 314 genes of poplar. The results show that the main trend was highly negative correlated with the gene expression level assessed by the ''Codon Adaptation Index'' value. Moreover, there were two significant correlations between axis 1 coordinates and GC3(s) content and gene length, we infer that gene nucleotide composition and gene length also play an important role in shaping the codon usage bias in poplar. The result of relative synonymous codon usage (RSCU) analysis shows a high bias of codon usage toward the codon with A or T ending. In addition, we compared the codon preferences among poplar, Arabidopsis thaliana, Oryza sative, Homo sapiens and Escherichia coli, and poplar was found to be most similar to A.thaliana and least similar to E.coli. In this paper, 10 codons defined firstly as optimal codons through an analysis of the high-expression codon in poplar may provide some useful information for genetic engineering of poplar.