植物生理与分子生物学学报最新文献

Through observing the responses of photosynthesis in leaves of broad bean grown under natural conditions to light and CO(2) using a portable photosynthetic analyzer LI-6400, the following findings were obtained. (1) Observing the response of photosynthesis to light using a leaf without being induced by light might lead to an artifact that photosynthesis was not saturated even under full sunlight. (2) The calculated saturating light intensity of photosynthesis by some empirical equations was much lower than actual value obtained by observing. (3) During observation of photosynthetic response to CO(2), each step of changing CO(2) concentration should be accompanied by a match step of the photosynthetic analyzer, otherwise, there will be substantial deviations in the results obtained. (4) Observing photosynthetic response to CO(2) at non-saturating light might lead to an underestimation of leaf photosynthetic capacity.

The cell wall material (CWM) and eight cell wall polysaccharides fractions were extracted from 'Fuji' and 'Kinsei' apples during storage at different time (0 and 42 days). The sugar composition characteristics of each fraction were determined by gas chromatography. The results showed that, during storages, the firmness of 'Kinsei' apples decreased significantly, and a significant peak of ethylene production was shown after 10 d storage, but only a little ethylene was produced in 'Fuji' apples, which had a better storability. Compare to other cell wall polysaccharide fractions, in Na(2)CO(3)-soluble pectic fractions of apple fruit, there were abundant rhamnogalacturonan I (RG-I), which branched highly in side chains due to the compositions of arabinans, galactans, arabinogalactans etc. As for cell wall polysaccharides, in 'Kinsei' apples, the decrease of pectic fractions was shown most significantly in Na(2)CO(3)-1 fraction, which was associated with a significant degradation of arabinosyl and galactosyl residues on the side chains. Further more, higher molecular mass in Na(2)CO(3)-1 pectic polysaccharides degraded and turned into ones with smaller molecular mass. From these results, the degradation of side chains in Na(2)CO(3)-1 pectic polysaccharides under the activity of enzyme was considered one of the most significant factors of apple fruit softening through modifying the network of cell wall polysaccharides.

The cDNA of Alocasia macrorrhiza lectin (aml, GenBank accession number: DQ340864) was cloned by RACE-PCR and its characteristics were predicted by various bioinformatics tools. GSPs (Gene Specific Primers) were designed according to the conserved regions of the genes encoded for lectins and similar proteins from the same family Araceae. Total RNAs were extracted from the tubers of A macrorrhiza by Qiagen RNeasy mini kit. The 3'- and 5'-RACE-PCRs were performed with the isolated total RNAs by SMART(TM)RACE cDNA amplification kit from BD Biosciences Clontech Company, respectively. The purified PCR products were ligated with pMD 18-T vector, and the confirmed clones were sequenced. The full-length cDNA of aml was obtained by combination of 3'- and 5'-end sequences, and was then confirmed by full-length 3'-RACE-PCR. The aml cDNA is 1 124 bp long. The deduced amino acid length of AML lectin is 270 aa. Its relative molecular weight is 29.7 kD. The results of homologous analysis showed a high similarity between AML and other mannose-binding lectins and similar proteins from Araceae family. Two typical B-lectin domains and three mannose- binding motifs were found in the sequence of AML. With all these taken together, it can be concluded that this newly cloned aml cDNA encodes for a mannose-binding lectin.

Under phosphate deficiency stress, the mRNA levels of PLDalpha and PLDbeta in tobacco older leaves were higher while in rapid developing ones were lower than those in controls. In addition, changes in PG hydrolase activity were positively correlated with the alternation of transcript levels of PLDalpha and PLDbeta genes in both types of leaves. Phosphate deficiency resulted in decreases in PG content in both older and rapid developing leaves, and that the extent of decrease in older leaves was much larger than that in rapid developing ones. Phosphatidic acid (PA) is one of the main hydrolysis product of PG. Its production was restricted by adding n-butanol, an inhibitor of PA formation via PLD pathway, to the in vitro enzyme reaction mixture. These results suggest that the enhanced PG hydrolase activity is one important cause of the decrease in PG content in older leaves, and the activity of PG hydrolase is regulated at the transcriptional level.

Delta-12 desaturases are involved in the conversion of oleic acid to linoleic acid in plant. Based on the conserved oligo amino acid residues of the published delta-12 desaturase genes from other higher plant species, a cDNA fragment was amplified by RT-PCR (reverse transcriptase-polymerase chain reaction) from the total RNA of immature maize embryos. According to bioinformation analysis of the cDNA sequence, a specific fragment of FAD2 gene was isolated by RT-PCR from immature maize embryos, and DNA of the same length was amplified from maize genome. Results of sequence analysis indicate that they are all 1 164 bp long, and have just an open reading frame (ORF) coding for 387 amino acids, and there is no intron in the FAD2 ORF (GenBank accession DQ496227). The deduced amino acid sequence of the cloned FAD2 showed high identity to those of other plant delta-12 fatty acid desaturases. It contains three histidine motifs and two long stretches of hydrophobic residues, indicative of an integral membrane protein spanning membrane four times. Analysis by semi-quantitive RT-PCR showed that FAD2 was strongly expressed in maize immature embryos than in leaves, stems and roots.

A seed-specific Fad2 gene expression cassette, which is free-marker gene and with sense and antisense structure, was constructed by using the promoter and terminator of rape seed storage protein cruciferin gene. Transgenic rape plants without selection marker genes were obtained by Agrobacterium-mediated transformation. The oleic acid content of transgenic plant seeds is 83.9%, which is nearly the same as that of Brassica napus with double Fad2 mutation (85%). The result of RT-PCR analysis shows that the raising of oleic acid content may be due to the degradation of Fad2 mRNA induced by co-transformation of sense-antisense Fad2 gene. These transgenic plants with high oleic acid trait grew normally and without the disadvantageous agronomic traits such as weak cold resistance, tardy development, death of buds and low rate of seed setting caused by Fad2 inactivation in mutant Brassica napus plants. This work would serve as a good base for breeding of more lines with high oleic acid content.

This paper studied on the effect and mechanism that the growth of M. aerugonsa was markedly inhibited by the H. verticillata culture water. During treatment, the photosynthetic rate of M. aerugonsa declined, while its respiratory rate and SOD activity increased firstly, then decreased as the treatment went on. Its membrane permeability also increased significantly. TEM photographs showed that the ultrastructure of cell membrane, thylakoid lamella and pith nucleoid of M. aerugonsa were destroyed severely. Inhibitory effects could be observed only when the extracts were extracted by ether. The more extracts from ether, the better inhibitory effect observed. It suggested that the inhibitory effects of H. verticillata on M. aeruginosa were through excreting substances into water. GC/MS analytic result showed that the ether extract mainly consisted of 1,2-benzenedicarboxylic acid diisooctyl ester, dibutyl phthalate, and 1,2-benzenedicarboxylic acid butyl 2-methylpropyl ester.

Fluorescence-marked lipid binding experiment shows that CaMBP-10 has typical lipid binding feature of non-specific lipid transfer protein (nsLTP). We have compared the effects of calmodulin (CaM) on the lipid-binding activity of CaMBP-10 and maize nsLTP. Different influences were found in the presence of either Ca(2+) or EGTA. W-7 and TFP could abolish the influence of CaM. Therefore, it is suggested that CaM could interact specifically with both CaMBP-10 and maize nsLTP. Probably, there are different CaM regulatory mechanisms between CaMBP-10 and maize nsLTP.

Using the information about the sequence from a differentially expressed clone (designated as HbSSH10) encodes a protein specifying a cysteine-rich sequence containing a putative "RING finger" or "C3HC4" consensus motif that was cloned recently by the subtractive hybridization between latex and leaves from rubber tree (Hevea brasiliensis). A full-length cDNA encoding C3HC4 type zinc-finger protein was isolated and characterized from rubber tree. Sequence analysis revealed that the ORFs of HbRZF encode 156 amino acid residues with a total predicted molecular mass of 17.2 kD, HbRZF protein having a putative "RING finger" segment (amino acid residues 100-144). The deduced amino acid sequences of HbRZF showed high identities of 48%, 52% and 50% to those of the ring zinc protein from Poncirus trifoliata, Arabidopsis thaliana, Thellungiella halophila. The result of Northern blot analysis indicated that the transcripts of the HbRZF were expressed more in the latex than in the leaves, whereas little expression was detected in roots and flowers. The transcription of HbRZF was induced by jasmonic acid, whereas ethylene had little effect.

Changes in cell wall structure, decrease in tissue firmness and ethylene production in honey peach [Prunus persica (L.) Batsch, cv. 'Yuhuasanhao'] were investigated after various storage at 5 degrees C and at 20 degrees C. The results showed that during storage, the peak of ethylene production lagged significantly behind the rapid softening of peach fruit, which means that it is not ethylene causes the softening of peach fruit. The structural and compositional changes of cell wall of fruits stored at 5 degrees C and at 20 degrees C suggested that low temperature storage inhibited the changes in pectins and cell wall materials (CWM)-residue fraction and delayed the softening of peach fruit. Ruptures of the pectic main chains rich in galacturonic acid occurred. Loss of arabinose and galactose was detected both in pectins and CWM-residue. These results suggested that softening of harvested peach fruit involved the solubilization and degradation of side chains of pectin and CWM-residue fraction, which were probably due to the increased activities of cell wall polysaccharide-related enzymes. However, the loss of neutral sugars in hemicellulosic polysaccharides was not correlated with fruit softening.