Two putative stress-related genes were isolated from sweetpotato and were designated as IbPRP1 and IbPRP2 (Ipomoea batatas proline-rich proteins 1 and 2). The deduced amino acid aligment of IbPRP1 and IbPRP2 shows that these two genes belong to the AAI_LTSS superfamily. Proteins in this family are known to play primary roles including defending plants from pathogens and insects, lipid transport between intracellular membranes, and nutrient storage. The mRNA expression of IbPRP1 and IbPRP2 were investigated and the results demonstrate that IbPRP2 has tissue-specific expression. Moreover, IbPRP1 and IbPRP2 may be involved in response to various stresses including drought, pathogen, and oxidative stress. In addition, when leaf disc test was performed, the IbPRP1 transgenic tobacco plants showed increase in tolerance to salt (100 mM, 200 mM, and 300 mM). Moreover, IbPRP1 and IbPRP2 may have some roles of transmembrane protein in sweetpotato when checked through GFP fusion cell localization and transmembrane analysis. All of these results indicate that IbPRP1 and IbPRP2 might play an important role in plant stress responses.

Previously, two events (H15 and B20) of transgenic pepper (Capsicum annuum L.) that enhanced resistance to Cucumber mosaic virus (CMV) by the introduction of CMV coat protein (CP) gene were constructed. Presently, a single copy number of the CP gene was revealed in H15 and B20 by Southern blot. To predict possible unintended effects due to transgene insertion in an endogenous gene, we carried out sequencing of the 5'-flanking region of the CP gene and a Blastbased search. The results revealed that insertion of the transgene into genes encoding putative proteins may occur in the H15 and B20 transgenic event. Mutiplex polymerase chain reaction (PCR) for simultaneous detection and identification of transgenic pepper was conducted with a set of nine primers. Both transgenic event were differentiated from non-transgenic event by the presence of 267 bp and 430 bp PCR products indicative of CP gene specific primer pairs and primer pairs targeting the CP gene and 35S promoter. H15 and B20 uniquely possessed a 390 bp and 596 bp PCR product, respectively. The presence of a 1115 bp product corresponding to intrinsic pepper actin gene confirmed the use of pepper DNA as the PCR template. The primer set and PCR conditions used presently may allow the accurate and simple identification of CMV resistant transgenic pepper.

A novel gene, denoted IbEF1isolated from sweet potato corresponded to the most abundant mRNA present in root tissue under salt stress. However, the encoded protein did not accumulate in the shoots. Transgenic tobacco plants were generated to elucidate the physiological function of IbEF1. The extent of early flowering of these plants correlated well with the level of IbEF1 expression, implicating IbEF1 as a positive regulator of flowering of tobacco plants. Over-expression of IbEF1 enhanced the AP1 gene in response to flowering time, but not floral organ development. These results demonstrate that simple manipulation of IbEF1 activity has great potential with regard to flowering time.