The role of Arabidopsis AtFes1A in cytosolic Hsp70 stability and abiotic stress tolerance.

AtFes1A is induced by high temperatures, and encodes a protein containing the armadillo repeat motif. Little is known about its biological function, however. In this study, we observed an increased heat-sensitive phenotype in atfes1a mutants, suggesting the involvement of AtFes1A in acquired thermotolerance. We found that AtFes1A is cytosolic and associates with cytosolic Hsp70. Loss of AtFes1A leads to a selective reduction of cytosolic Hsp70 and a global increase in heat shock transcription. Thus, AtFes1A appears to prevent cytosolic Hsp70 degradation, and acts as a negative regulator of heat-shock transcription. We also found increased ubiquitination of total protein in atfes1a mutants after severe heat stress. These findings suggest that AtFes1A plays an important role in heat response signalling pathways, in addition to its role in thermotolerance.

Cloning and functional characterization of a cation-chloride cotransporter gene OsCCC1.

Potassium (K+) and chloride (Cl-) are two essential elements for plant growth and development. While it is known that plants possess specific membrane transporters for transporting K+ and Cl-, it remains unclear if they actively use K+-coupled Cl- cotransporters (KCC), as used in animals, to transport K+ and Cl-. We have cloned an Oryza sativa cDNA encoding for a member of the cation-Cl- cotransporter (CCC) family. Phylogenetic analysis revealed that plant CCC proteins are highly conserved and that they have greater sequence similarity to the sub-family of animal K--Cl- cotransporters than to other cation-Cl- cotransporters. Real-time PCR revealed that the O. sativa cDNA, which was named OsCCC1, can be induced by KCl in the shoot and root and that the expression level was higher in the leaf and root tips than in any other part of the rice plant. The OsCCC1 protein was located not only in onion plasma membrane but also in O. sativa plasma membrane. The OsCCC1 gene-silenced plants grow more slowly than wild-type (WT) plants, especially under the KCl treatment regime. After 1 month of KCl treatment, the leaf tips of the gene-silenced lines were necrosed. In addition, seed germination, root length, and fresh and dry weight were distinctly lower in the gene-silenced lines than in WT plants, especially after KCl treatment. Analysis of Na+, K+, and Cl- contents of the gene-silenced lines and WT plants grown under the NaCl and KCl treatment regimes revealed that the former accumulated relatively less K+ and Cl- than the latter but that they did not differ in terms of Na+ contents, suggesting OsCCC1 may be involved in K+ and Cl- transport. Results from different tests indicated that the OsCCC1 plays a significant role in K+ and Cl- homeostasis and rice plant development.

Expressed sequence tags from the halophyte Limonium sinense.

Halophytes can grow under a high salinity condition. Similar to glycophytes, their salt-tolerance possesses a high genetic complexity. There are many morphological and physiological studies on halophytes but very little information is at molecular level why they are salt-tolerant. Limonium sinense is a salt-secreting halophyte and can excretes salts by multi-cellular glands. Here, we report the library construction and sequence analysis of a cDNA library made from leaf tissue of L. sinenes. Among those 1082 expressed sequence tag (EST) obtained, 684 unique genes were identified: 429 showed homology to previously identified genes, 255 matched to uncharacterized genes. Compared with other EST databases, some characteristic features such as abundance genes in related to cytoskeleton and intracellular traffic, membrane transporting were observed, which may be specific to halophytes.

[Transferring the Suaeda salsa glutathione S-transferase and catalase genes enhances low temperature stress resistance in transgenic rice seedlings].

The GST (glutathione S-transferase) and GST+CAT1 (catalase 1) of Suaeda salsa were introduced into a low temperature-sensitive rice cultivar (Oryza sativa cv. Zhonghua No.11) by Agrobacterium tumefaciens-mediated transformation under the control of cauliflower mosaic virus (CaMV) 35S promoter, and the transformed calli and plantlets were screened on Murashige and Skoog (1962) medium supplemented with hygromycin 25 microg/mL and cefotaxime 300 microg/mL. The putative primary transformants (T(0) generation) were acclimatized at 26 degrees C /22 degrees C in a greenhouse for 7 d, and then transplanted to the field, where they grew up to maturity under outdoor conditions. 25 and 14 independent transgenic lines of T(1) generation carrying the GST and GST+CAT1 genes, respectively, were identified by PCR amplification. Transgene expression was monitored by RNA-blot hybridization using total RNA samples from leaf tissues. To investigate whether expressing the Suaeda salsa GST and GST+CAT1 in transgenic rice increased low temperature stress tolerance, the T(4) 14-day-old transgenic and non-transgenic rice seedlings were transferred to a low temperature (day 7 degrees C/night 4 degrees C) growth chamber for 3-6 d. The experimental data showed that expressing the Suaeda salsa GST and GST+CAT1 enhanced low temperature stress resistance in transgenic rice seedlings. When treated with low temperature, both GST and CAT activity increased in the transformants with the time of temperature treatment. These transgenic rice plant seedlings exhibited a higher level of photosynthetic capacity than those of the non-transgenic control seedlings under low temperature treatment. Whereas, there were lower H(2)O(2) and MDA (malondialdehyde) content, and relative electrolyte leakage through the plasma membrane was also lower in transgenic rice seedlings than in the parent line under low temperature condition. The results also indicated that GST+CAT1 co-expression conferred greater level of low temperature stress tolerance to the transformed rice plants compared to the single GST transformed plants.

[The introduction of chloroplast gene engineering].

Chloroplast is a kind of special cell organ in plant cells.Since 1988,Scientists have realized its advantages in plant gene engineering.It's high efficient expression and safety made it been attached more and more importance to. This paper introduces the chloroplast transformation,including its advantages,methods,uses and defects.

[Na+/H+ antiporter and plant salt tolerance].

Na+/H+ antiporter plays an important role in mechanisms of the plant salt tolerance, it extrudes Na+ from cell energized by the proton gradient generated by the plasm membrane H(+)-ATPase and/or compartmentalizes Na+ in vacuole energized by the proton gradient generated by the vacuolar membrane H(+)-ATPase and H(+)-PPiase. This review mainly discusses the latest progress in the study of Na+/H+ antiporter in plant and yeast at molecular level.