The sweetpotato whitelfy Bemisia tabaci distribute worldwide and infests more than 500 species of plants. To determine nutritional stress of whiteflies at molecular level, we identified a full cDNA of glucose regulated protein 78 (grp78) which is known to be respond to nutritional restriction in vertebrate species. GRP78 of B. tabaci was highly conserved motifs of the HSP70 family and the C-terminal motif of KDEL characteristic of endoplasmic reticulum-specific HSPs. Real-time RT-PCR analysis showed that the grp78 level was not changed by thermal stress treatment from 4°C to 40°C for 1 h. However, the grp78 level was proportionally increased to the ingestion of a sucrose solution ranging in concentrations from 0% to 30% in a Parafilm feeding chamber. In addition, the grp78 levels were various by the ingestion of leaves of 10 different plants for 24 h; its level was higher with eggplant and pepper but lower with rice and apple. Our study suggests that the grp78 may have a role for cellular chaperones in relation to nutritional uptake of B. tabaci.

Susceptible Vitis vinifera responds to Xylella infection with a massive redirection of gene transcription. This transcriptional response is characterized by increased transcripts for phenlypropanoid and flavonoid biosynthesis, ethylene production, adaptation to oxidative stress, and homologs of pathogenesis related (PR) proteins, and decreased transcripts for genes related to photosynthesis. In addition, the results suggest that susceptible genotypes respond to Xylella infection by induction of limited, but inadequate, defense response. We also compared the transcriptional and physiological response of plants treated by pathogen infection, low or moderate water deficit, or a combination of pathogen infection and water deficit. Although the transcriptional response of plants to Xylella infection was distinct from the response of healthy plants to moderate water stress, we observed synergy between water stress and disease, such that water stressed plants exhibit a stronger transcriptional response to the pathogen. This interaction was mirrored at the physiological level for aspects of water relations and photosynthesis, and in terms of the severity of disease symptoms and pathogen colonization, providing a molecular correlation of the classical concept with the disease triangle.

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.

Proline is known as an osmotrotectant to enhance tolerance against both salt and dehydration stresses. A P5CS (δ1 -pyrroline-5-carboxylate synthetase) plays a major role in regulation of synthesis of proline. An overexpression of the mothbean P5CS gene in transgenic tobacco plant increased the levels of proline and osmotolerance. In an attempt to look for the possibility to use content of proline as well as a level of P5CS gene expression as molecular markers for salt tolerance, the amounts of proline and transcript levels of P5CS were measured as functions of either concentration of NaCl or length of treatment period among different species of zoysiagrass. Hybridzoysia showed the highest level of proline (329~mu~textrmg /g.f.w.) among five different species of zoysiagrass at 250 mM NaCl in 24 hours. The level of P5CS transcript was also the highest in the hybridzoysia at 250 mM NaCl in 24 hours. The transcriptions of P5CS gene were induced at the rates of 1.2, 1.2, 1.8, and 1.8, upon treatment of 250 mM NaCl in Z. japonica, Z. matrella, Z. sinica and hybridzoysia respectively. Based on a correlation between the level of P5CS transcript and the proline content among different species of zoysiagrass, a comparative structural analysis of the gene for P5CS from either Z. sinica or hybridzoysia may lead to an understanding of mechanism for salt tolerance shown differently among zoysiagrasses.