植物生理与分子生物学学报最新文献

The effect of light condition during post-harvest storage on fruit quality of 'Hakuho' peach (Prunus persica Batsch) was examined. Fruits were harvested at the immature stage (7 d before the tree-ripening stage) and firm-ripe (3 d before the tree-ripening) stage and stored at 25 degrees C under light (ca 80 micromol m(-2) s(-1) at the fruit top by a fluorescent lamp) and in darkness. The light and dark conditions did not significantly influence the ethylene production rate except for the fully ripened fruits harvested at firm-ripe stage and stored under light. However, no difference in fruit firmness was detected among treatments at full-ripe stage. The skin anthocyanin content increased significantly during storage under light. Total soluble solid (TSS) content of juice at the full ripe stage was not affected significantly by the storage condition, although titratable acidity (TA) in immature harvested fruits decreased more quickly during storage under light compared with those stored in darkness. Dark storage limited the decrease in juice asparagine to some extent. Aromatic lactones, such as gamma-decalactone and gamma-dodecalactone, both in skin and in flesh tissues increased more rapidly when the fruits were stored under a light condition, irrespective of fruit harvest stage. From these results, we conclude that fruit storage under a light condition is better for fruit quality of the 'Hakuho' peaches than storage in darkness.

The effect of SNP, an NO donor, on seed germination of wheat (Triticum aestivum L. cv. 'DK961') under salt stress was studied. The results showed that priming of seeds with 0.06 mmol/L SNP for 24 h markedly alleviated the decrease of the germination percentage, germination index, vigor index and imbibition rate of wheat seeds under salt stress. SNP significantly alleviated the decrease of the beta-amylase activity but almost did not affect the alpha-amylase activity of wheat seeds under salt stress. SNP slightly increased the alpha-amylase isoenzymes (especially isoenzyme 3) and significantly increased the beta-amylase isoenzymes (especially isoenzyme d, e, f and g). SNP pretreatment decreased Na(+) content, but increased the K(+) content, resulting in a mark increase of K(+)/Na(+) ratio of wheat seedlings under salt stress. These results suggested that NO is involved in promoting wheat seed germination under salt stress by increasing the beta-amylase activity.

Replication factor C (RFC), consisting of one large subunit and four small subunits, is an important factor involved in DNA replication and repair mechanisms as well as cell proliferation. The subunit 1 of Arabidopsis RFC (AtRFC1) is a homologue of p140, the large subunit of human RFC. Three T-DNA insertion mutant lines of AtRFC1, i.e. rfc1-1, rfc1-2 and rfc1-3, with insertion mutations located in exons 16 and 19, and the promoter region respectively were verified. These mutations caused defects in embryogenesis and led to embryo and seed abortion. Transformation of wild type AtRFC1 gene into rfc1 mutant alleles reverted the mutant phenotypes, suggesting that AtRFC1 plays an important role in embryo development in Arabidopsis thaliana.

Microprojectile bombardment-mediated transformation method has been developed for onion (Allium cepa L.) using embryogenic calli, induced from stem discs, as target tissue. Zinc-finger protein gene OSISAP1 (Oryza sative subspecies indica stress-associated protein gene) was introduced into the open-pollinated onion cultivar (subs.) 'HG400B'. Bombardment parameters were optimized as: the pressure is 1,100 psi, the distance is 6 cm, two times, the ratio of mass between plasmid DNA and golden particles is 1:320. An efficient microprojectile bombardment-mediated transformation system of onion (Allium cepa L.) callus has been established. The binary vector used carried the nptII gene for kanamycin resistance and the GUS reporter gene. Transgenic cultures were screened for their ability to express the GUS reporter gene and to grow in the presence of kanamycin (150 mg/L). Transient expression of GUS reporter gene was observed through histochemical staining of embryogenic callus transformed by microprojectile bombardment. The putative transgenic plants were analysed at the molecular level using PCR, southern hybridization, and RT-PCR. The results confirmed that the OSISAP1 gene was integrated as one copy into the genome of onion and expression. Transgenic plants were produced efficiently with a transformation frequency of about 10%. Test of salinity-alkali stress showed that sodium chloride and sodium bicarbonate at 200 mmol/L effectively killed non-transgenic plants within 1 week of irrigation, while the transgenic plants were completely unaffected by salinity of 400 mmol/L. So transformation with the OSISAP1 gene raised the salinity-alkali-tolerance of the transgenic plants to a high level.

After seedlings of Aeluropus sinensis var. sinensis Debeaux were treated with different NaCl concentrations (0-200 mmol/L) for 14 days, some physiological indexes were measured. The higher the NaCl concentration, the more the growth of A. sinensis was inhibited. The increase in root/shoot ratio suggests that the shoots are more sensitive to salinity than the roots. The diminished leaf area may reduce the transpiration rate, and the root mainly grew longitudinally, which may help the root to reach the water source under the high salinity conditions. Chl a contents increased, so did Chl b, but the Chl a/Chl b ratio declined, which implies the stimulation of Chl a accepted from NaCl is smaller than that of Chl b. After salt treatment, the organic solute contents increased (P<0.05), the proline, amino acids and soluble sugar contents increased more than organic acids, the increase in soluble carbohydrate may inhibit photosynthesis in feedback. The percentage of sucrose in soluble carbohydrates increased too. Although the organic dry weight of whole plant declined, the proportion of organic dry weight in total dry weight increased, and the osmotic potential of plant cell juice declined, which implies that the contribution of organic matter to osmotic adjustment increased with salinity. That is, A. sinensis had ability to tolerate salinity to a certain degree.

This paper reported the synergistic effect of KT and IAA, and the effects of age of seedlings, length of hypocotyls, nitrogen contents and NH(+)(4)-N/TN ratio on the induction of female flowers in derooted seedlings of Cucumis sativus L. for the establishment of an efficient system for the induction of female flowers. When cultured on MS basal medium supplemented with KT 3.0 mg/L and IAA 0.01 mg/L, an induction rate of 28% was obtained for the 7-day-old derooted seedlings with 1/2 hypocotyl, 12% and 26% higher than when cultured with KT 3.0 mg/L alone and IAA 0.01 mg/L alone, respectively, while no female flowers was formed on the control medium, which indicates that KT and IAA have an evident synergistic effect on the induction of female flowers. Experiment was done with N concentration of 60-90 mmol/L or with NH(+)(4)-N/TN ratio of 12.5%-50% (total N kept at 80 mmol/L), with lengths of hypocotyls of 0-4/4, and with different ages of seedlings of 5-8-day-old, the highest induction rate of 40%, 48% and 57% for female flowers was achieved on medium of N 80 mmol/L (NH(+)(4)-N/TN 37.5%), from seedlings with 1/4 hypocotyl and from the treatment using 6-day-old seedlings respectively.

Besides the non-cyclic electron transport driven by the two photosystems (PSII and PSI), the cyclic electron transport pathways around PSI are also essential for efficient photosynthesis. As one of these pathways, the NAD(P)H dehydrogenase complex (NDH complex) mediated cyclic electron transport has been well studied. Along with the identification of the plastid terminal oxydase (PTOX), the functions of NDH-mediated cyclic and chlororepiratory electron transport in energy supply for photosynthesis as well as in the resistance to photooxidative stress have increasingly been brought to the researchers' attention. In the present paper, the structural characteristics of NDH complex, the regulatory mechanism, and the physiological significance of NDH mediated cyclic electron transport and chlororespiration are reviewed.

Percentage of grains with chalkiness (PGWC), one of the important traits assessing rice grain appearance quality, belonged to qualitative trait controlled by many genes. Our previous study identified a novel quantitative trait locus (QTL), namely qPGWC-9, related to high PGWC using chromosomal segment substitution line (CSSL) population. qPGWC-9 was shown to be expressed stably in eight environments. AIS82 which carried a IR24 chromosomal segment corresponding to qPGWC-9 in the Asominori genetic background was selected and analyzed to clarify the physiological function of qPGWC-9 from the relationship of source and sink of carbohydrates. It showed that AIS82 had higher PGWC than Asominori (control variety with low PGWC). The net photosynthetic rate of flag leaf of AIS82 showed no significant difference from that of Asominori, so photosynthetic ability in flag leaf was not directly related with high PGWC in AIS82. But, the changes in pattern of activity of the key enzymes associated with starch synthesis were different in these plants. Activities of some key enzymes in starch synthesis in AIS82 changed more radically than those in Asominori. These results suggest that qPGWC-9 might determine the activities of some enzymes associated with starch synthesis and therefore affect the degree of grain chalkiness.

Longan (Dimocarpus longan Lour.) fruits are very susceptible to pericarp browning and aril breakdown, and postharvest aril breakdown is one of the most important factors degrading the quality and shorting storage life of longan fruit. Changes in aril breakdown index, cell wall components and cell wall-degrading enzyme activities in aril of longan cv. Fuyan fruits using sealed polyethylene film bags (0.015 mm thick) at (10+/-1) degrees C were investigated. The main results were as follows. Development of aril breakdown was higher with storage time (from day 0 to day 36). Aril breakdown index was positively and significantly correlated with storage time (P<0.01). During development of aril breakdown, the total dry weight of the cell wall materials, protopectin, cellulose, semicellulose and cell wall protein contents of aril decreased progressively. The total dry weight of the cell wall materials, contents of protopectin, cellulose, semicellulose and cell wall protein of aril were all negatively correlated with aril breakdown index. There were low beta-galactosidase activity, and high activities of pectinesterase (PE), polygalacturonase (PG) and cellulase in aril of harvested fruit. PE activity in aril gradually decreased during development of aril breakdown. The activities of PG and cellulase in aril increased significantly during storage from day 6 to day 12 and from day 0 to day 12, respectively. The peaks enzyme activities of both PG and cellulase appeared on the 12th day after harvest, then the enzyme activity decreased; whereas, the activities of PE, PG and cellulase changed little from day 0 to day 24, and then rapidly decreased. The beta-galactosidase activity in aril decreased slightly during storage from day 0 to day 24. However, the beta-galactosidase activity increased significantly after day 24. Especially, the beta-galactosidase activity increased rapidly after 30 d of storage, in the meantime, the activities of PE, PG and cellulase almost disappeared. From the results it can be seen that the development of aril breakdown was due to the degradation of cell wall components such as protopectin, cellulose, semicellulose and cell wall protein. The early and middle phases of development of aril breakdown were mainly brought about by the action of PE, PG and cellulase, whereas, beta-galactosidase played the key role at the late phase of aril breakdown.

Selective microelectrode technique, known as an electrophysiological approach, can be used to measure directly specific information on ion or molecule distribution and movement both inside and outside of living organelle, biological cells, tissue and organs. It has several advantages over other methods in measuring ionic or molecular information, e.g. easy to handle, fast response, high sensitivity (10(-12) moles cm(-2) s(-1)) and non-invasive to the samples in addition to continuous measurement and automatic monitoring. Microscopic-scale selective electrode (with a tip diameter of 0.5-5 microm) can be used to measure net fluxes of ions or molecules outside of growing biological cells, tissues and organs, to measure activities of ions or molecules inside of growing organelle and biological cells. Thus, it has many applications in various research fields. The technical principle of design and use of selective microelectrode and its progress and development prospect in plant physiological research are summarized.