애기장대의 AtSIZ3(At1g08910) 유전자에 T-DNA를 삽입한 세 종류의 변이형에 저온(4℃), 고온(37℃) 및 건조스트레스를 처리하여 유묘의 생장반응과 유전자 발현을 조사하였다. 저온과 고온처리에 의해서는 야생형과 변이형간에 유묘생장에 유의한 차이를 보이지 않았다. 야생형과 변이형 식물체에 10일간의 건조스트레스를 처리하면 야생형은 재 관수에 의해 모든 식물체가 재생하였으나 변이형은 모두 고사하였고, 10일간의 건조처리로 변이형은 야생형에 비해 유묘생장이 평균 62.9%가 억제되는 것으로 나타났다. 야생형에서 AtSIZ3 유전자는 4℃의 저온처리에서 무처리를 보다 20%정도 발현이 감소하는 반면, 37℃ 고온처리에서는 3.7배, 건조처리에서는 4.5배가 증가하였다. 이 결과로 보아 AtSIZ3 유전자는 식물의 건조내성과 밀접한 연관이 있을 것으로 판단된다.

Photorespiration reduces carbon fixation rate, but is essential process in plant. Photorespiration involves reactions in chloroplasts, peroxisomes, and mitochondria. In photorepiratory peroxisome, alanine glyoxylate aminotransferase (AGT) catalyzes alanine and glyoxylate into glycine and pyruvate. We isolated a low temperature-inducible cDNA encoding AGT from mungbean leaves. The full-length cDNA, designated as MLT9, contains an open reading frame of 1,203 nucleotides coding for a protein of 401 amino acids. Genomic DNA blotting showed that the mungbean genome has one copy of MLT9. MLT9 mRNA was induced not only by low temperature but also by drought stress, but ABA and NaCl did not induce RNA expression of MLT9. In mungbean, AGT activity was higher in the non-stressed leaves compared to the low-temperature treated leaves. Based on GFP/RFP targeting experiment, GFP-MLT9 fusion protein and SKL-RFP, a peroxisome marker, were colocalized to peroxisome in tobacco protoplasts. This suggests that peroxisomal MLT9 plays a role in photorespiratory metabolism in response to low temperature and drought stress.

We have cloned an LTP gene (PoLTP1) from poplar (Populus alba × P. tremula var. glandulosa) suspension cells and examined changes in its expression levels in response to various stresses and ABA treatment. The full-length PoLTP1 cDNA clone encodes a polypeptide of 116 amino acids with typical characteristics of LTPs, notably a conserved arrangement of cysteine residues. Southern blot analysis indicate that two or three copies of the PoLTP1 are present in the genome of the investigated hybrid poplar. In addition, northern analysis of samples from soil-grown plants indicate that PoLTP1 is tissue-specifically expressed in the leaves and flowers. The gene is significantly up-regulated by treatment with mannitol, NaCl and ABA, but not by either cold or wounding. These results indicate that PoLTP1 is involved in osmotic stress responses in poplar plants and suspension cells.

In order to uncover gene regulatory networks clustering of co-expressing genes was performed using a rice micorarray dataset of 155 gene expression omnibus sample (GSM) plates in NCBI, generating a total of 1660 clusters. One cluster with 85 co-expressing genes was measured with the correlation coefficient between pairs, resulting in an average r value of 0.66 with a range of -0.08 to 0.98. This result might support the notion that genes included in each cluster play common functional role(s). We also retrieved 23 Affymetrix GeneChip spots IDs corresponding to each of candidate genes related to abiotic stresses obtained from the P1antQTL-GE database and subsequently detected 23 clusters including co-expressing genes with each of the genes. Expression profiles of co-expressing genes revealed some degree of tissue-specific expression patterns, probably reflecting the existence of, at least partial, parallel versions of stress-related networks with evolutionary process, such as subfuntionalization. The finding that several cis-elements related to abiotic stresses was detected by differences in frequency between co-expressing genes and randomly selected genes. Clustering, expression profiles, and putative cis-acting regulatory elements of co-expressing genes related to abiotic stresses may provide clues to shed further light on the gene regulatory network of stress-responsive pathway.

세포의 대사과정에서 생성되는 활성산소종(reactive oxygen species : ROS)은 세포의 성숙과 발생 과정을 저해하며, 인간의 생식 수관에서 불임의 원인이 된다. 많은 세포생물학적 연구를 통해 ROS에 대한 세포 내의 보호 기작이 밝혀지고 있다. Activating transcription factor 4(ATF4)는 세포 내에서 산화적 스트레스를 비롯한 여러 스트레스 요인으로부터 세포를 보호하는 기작에 관여하는 중요한 인자로서, 스트레스

Osmotic stress is one of major limiting factors in crop production. In particular, seasonal drought often causes the secondary disease in the field, resulting in severe reduction in both quality and productivity. Recent efforts have revealed that many genes encoding protein kinases play important roles in osmotic stress signal transduction pathways. Previously, the AtSIK (Arabidopsis thaliana Stress Inducible Kinase) mutants have shown to enhance tolerance to abiotic stresses, accompanying with higher expression of abiotic stress-related genes than did the wild-type plants. In this study, we have transformed potato (cv. Taedong Valley) with the AtSIK expression cassette. Both PCR and RT-PCR using AtSIK-specific primers showed stable integration and expression of the AtSIK gene in individual transgenic lines, respectively. Foliar application of herbicide (Basta®) at commercial application rate (0.3% (v/v)) revealed another evidence of stable gene introduction of T-DNA which includes the bar gene for herbicide resistance. Overexpression of the AtSIK gene under dual CaMV35S promoter increased sensitivity to salt stress (300 mM NaCl), which was demonstrated by the reduction rate of chlorophyll contents in leaves of transgenic potato lines. These results suggest that possible increase of osmotic tolerance in potato plants may be achieved by antisense expression of AtSIK gene.