Recently, RNA interference (RNAi) technology has been emerged as a potent tool for pest control strategy. Based on the previous studies on RNAi via leaf disc-mediated systemic delivery of dsRNA and in planta expression of hairpin RNA by agroinfiltration, the coatomer subunit alpha (COPA) gene has been found to be a crucial target for RNAi against Tetranychus urticae. In current study, transgenic plants of Arabidopsis thaliana expressing COPA hairpin RNA were generated by the floral dip method. Putative transgenic plants were screened by PCR and positive transformants were subjected to bioassay using age-synchronized and host-adapted T. urticae. T. urticae feeding on plants expressing dsRNA/siRNA showed more than 80% mortality as compared to the mites feeding on control plants at 6 days post-infestation. Our data shows that in planta expression of hairpin gene such as COPA may serve as an effective way for the control of this important pest in ornamental and economically important plants.

We recently reported rice promoters that are active in late stages of pollen development. However, rice promoters that allow manipulation of gene expression at earlier stages of pollen development are still very limited to date. In this study, we have chosen 10 putative microspore promoters, OsMSP1 through OsMSP10, based on publicly available transcriptomic datasets in rice (Oryza sativa L.). Sequence analysis of these promoter regions revealed some cis regulatory elements involved in pollen-specific expression. We also examined promoter activities using the promoter-GUS reporter constructs in both transgenic rice and Arabidopsis. In rice, all of the 10 promoters directed GUS signals from the microspore stage throughout the all stages of pollen development. In addition, while GUS signals from 4 promoters, OsMSP2, OsMSP7, OsMSP9 and OsMSP10, seem to be expressed preferentially during pollen development, those from other six promoters were observed in vegetative tissues such as leaves, stems, and roots of seedlings. Similarly, in Arabidopsis, all of the 10 promoters directed GUS signals during pollen development. In detail, 8 promoters, OsMSP1 ~ OsMSP8 directed GUS signals from the microspore stage, whereas 2 promoters, OsMSP9 and OsMSP10, exhibited GUS signals from tricellular stage. Furthermore, seven promoters, except for OsMSP1, OsMSP2 and OsMSP10, showed GUS signals in shoot apical region or root tissues of seedlings. Furthermore, we verified microspore activity of four promoters, OsMSP1, OsMSP2, OsMSP3 and OsMSP6, by complementation analysis of the sidecar pollen (scp) mutant which displays microspore-specific defects. Currently, further analyses are underway for GUS expression of T2 generation in transgenic rice and scp complementation with remaining promoters.

Carotenoid isomerase (CRTISO) catalyzes the isomerization of prolycopene to all-trans-lycopene in the carotenoid biosynthetic pathway. We isolated a full-length promoter region of CuCRTISO from Citrus unshiu. We determined if the promoter encoded organ-specific or developmental-specific expression, and identified possible cis-acting promoter elements. The full-length promoter and two truncated versions were fused to the β-glucuronidase (GUS) gene and transformed into Arabidopsis thaliana. Transgenic lines expressing the full-length promoter (pCiso-Prom1) and truncated promoters (pCiso-Prom2 and pCiso-Prom3) showed the same developmental and organ-specific activity. GUS expression was detected in the cotyledon and root at 5 and 10 days after germination, mature leaf, and anther. The CuCRTISO promoter contained several cis-acting elements involved in hormonal and environmental stress. Drought stress or abscisic acid treatment did not induce GUS expression in any transgenic lines. Heat stress induced GUS expression in the pCiso-Prom1 line; this promoter construct contains the heat-stress responsive element (HSE). Ethylene and cold-stress treatments induced GUS expression only in the pCiso-Prom3 line, although all transgenic lines contained the same cis-acting ethylene and low-temperature response elements. which could indicate the existence of unknown repressor element(s) in the CuCRTISO promoter. These studies indicate that CuCRTISO promoter activity is regulated in a developmental and organ-specific manner that responds to heat, cold, and ethylene. These results provide new insights into the role of cis-acting element(s) in CuCRTISO promoter activity. (This research was supported by the Basic Science Research Program of the National Research Foundation of Korea (NRF) funded by the Ministry of Education (NRF-2010-0007627 and 2009-0094059), and by Golden Seed Project, Ministry of Agriculture, Food and Rural Affairs (MAFRA), Ministry of Oceans and Fisheries (MOF), Rural Development Administration (RDA) and Korea Forest Service (KFS), Republic of Korea)

Low temperature is a major factor restrict to growth and limiting productivity of rice crops. We used a cDNA microarray approach to monitor the expression profile of rice (Oryza sativa) under chilling stress and identified 20 chilling inducible genes in previously study. Ten such genes encoding bHLH, metal transporter and, zinc finger protein with unknown functions showed a significant change in expression under various abiotic stresses. Among them, OsCHI1 (Os07g15460), OsCHI2 (Os02g43660), and OsCHI3 (Os01g61160), were selected for further study. They have structural features such as metal-binding signature sequences in their protein sequences, and OsCHI genes were expressed in root of rice seedling and induced in chilling and salt or drought. Expression of OsCHI1, OsCHI3 and OsCHI2 were targeted to membrane and ER when transiently expressed in tobacco cell, respectively. The Arabidopsis (Arabidopsis thaliana) transgenic plants overexpressing showed increased tolerance to salt and drought stress in the seed germination and root elongation than that of wild type. This comprehensive study provides insight into the biological function of OsCHIs, which may be useful in understanding how rice plants adapt to unfavorable environmental conditions.

An Arabidopsis small GTPase, RabG3b, was previously characterized as a component of autophagy and as a positive regulator for xylem development in Arabidopsis. In this work, we assessed whether RabG3b modulates xylem-associated traits in poplar in a similar way as in Arabidopsis. We generated transgenic poplars (Populus alba x P. tremula var. glandulosa) overexpressing a constitutively active form of RabG3b (RabG3bCA) and performed arrange of morphological, histochemical, and molecular analyses to examine xylogenesis. RabG3bCA transgenic poplars showed increased stem growth due to enhanced xylem development. Autophagic structures were observed in differentiating xyelm cells undergoing programmed cell death (PCD) in wild type poplar, and were more abundant in RabG3bCA transgenic poplar plants and cultured cells. Xylogenic activation was also accompanied by the expression of secondary wall-, PCD-, and autophagy-related genes. Collectively, our results suggest that Arabidopsis RabG3b functions to regulate xylem growth through the activation of autophagy during wood formation in Populus, as does the same in Arabidopsis.

The MYB transcription factors play important roles in the regulation of many secondary metabolites at the transcriptional level. We evaluated the possible roles of the Arabidopsis R2R3-MYB transcription factor genes in flavonoid biosynthesis as they are induced by UV-B irradiation but are largely unexplored in terms of their associated phenotypes. We found that one member of this gene family, AtMYB60, inhibits anthocyanin biosynthesis in the lettuce plant. Wild type lettuce normally accumulates anthocyanin, predominantly cyanidin and traces of delphinidin, and develops a red pigmentation. However, the accumulation of anthocyanin pigments in AtMYB60 overexpressing lettuce was inhibited. We further found a complete absence of DFR transcripts in AtMYB60 overexpressing lettuce, whereas other biosynthetic genes in the anthocyanin metabolism pathway were expressed. To provide genetic tools the regulation of seed color of rapeseed which has been target for fuel, AtMYB was overexpressed in rapeseed. Transgenic plants showed lighter seed color and improved tolerance to abiotic stress than the wild type plants. The elucidation of the roles of the AtMYB60 transcription factor will facilitate further studies and provide genetic tools to better understand the regulation in plants of the genes controlled by the MYB-type transcription factors.