Research Interests
In tropical and subtropical areas, heat and drought are significant causes of reduced crop yield.  Heat shock proteins that are induced by heat and other stresses seem to have general protective functions. The hsp70 gene family includes members which are heat-inducible as well as cognate genes. Our previous study indicates that the tomato Lehsc70-3 has substantial levels of expression in various vegetative tissues, suggesting a general function of this hsc70 gene in tomato tissues.  To scrutinize the profile of gene expression in response to temperature and/or water stress is our major interest. Currently we are studying the expression pattern and possible function of stress proteins in mung bean (Vigna radiata), a common legume in southeastern Asia and an important edible crop in Taiwan. Our recent results indicated that de novo synthesized HSC70s may be required to escort the large amount of newly synthesized proteins during germination. We have isolated 3 VrHsc70 genes and identified 3 HSC70 proteins. The cDNA sequences suggest that the VrHsc70 genes do not code for the 3 HSC70 proteins. Therefore, we propose that there are two different groups of heat shock proteins in mung bean seeds/seedlings. One group was produced during seed maturation and may be important in desiccation tolerance. The other group is produced de novo from new transcripts of VrHsc70-1, 2, and 3 and may be related to the initiation of rapid growth of seedlings.
 

Nuclear DNA contents were estimated by flow cytometry in 18 Phalaenopsis Blume species and Doritis pulcherrima Lindl previously. Endoreduplication was found in various tissues of P. equestris at different levels with the highest degree in leaves. Different frequencies of endoreduplication were detected in an inflorescence of Phalaenopsis during development. The proportion of endoploidy in cells increased with the increasing size of a floral bud and regulated by the age of the organ. A mathematical model was developed to describe the kinetics of inflorescence development of Phalaenopsis in our study to provide a means to quantify the complex pattern of inflorescence development. Our results indicated that the dynamics of cell development and DNA endoreduplication in floral buds of orchid is similar to that in maize endosperm. Low temperature is required for Phalaenopsis to shift from vegetative growth to reproductive growth. However, chilling may cause lesion spots on leaves and decrease orchid production. To gain more insights of molecular mechanisms of chilling tolerance, genes possibly associate with chilling induction were isolated using the cDNA subtraction method.

Nonspecific lipid transfer proteins (LTPs) are widely found in plants. These proteins facilitate transport of lipids in vitro from one membrane to another. LTPs may have function such as allergens, proteases inhibitors, antimicrobial activities, and ameliorate of stresses. Although LTPs play an important role in plant acclimation to stress conditions, the mechanisms of LTP gene regulation remains unknown. To understand the functional properties of various isoforms of LTPs and the spatial, developmental, and stress-induced expression will gain an insight into the study of plant stress response. We attempt to characterize rice LTP and three mung bean LTP genes, including their nucleotide sequence analysis, and expression patterns in response to development, drought, cold, and ABA treatments.

Random amplified polymorphic DNA was applied for analysis of phylogenetic realtionships to examine interspecific and intraspecific variations among 18 genotypes, nine species of Nicotiana (sections Tomentosae and Alatae). Pair-wise comparisons of unique and shared amplification products were used to generate similarity coefficients with the computer software NTSYS. On the basis of the dendrogram constructed with similarity coefficients, the 18 Nicotiana genotypes were divided into two clusters. The classification analyzed by RAPD markers is in accordance with the classification of Goodspeed that N. sylvestris is a member of section Alatae. In collaboration with Drs. C. C. Chen and Y. Y. Kao at NTU, we have constructed a genetic linkage map for Nicotiana plumbaginifolia/Nicotiana longiflora (2n= 2x=20), based on the segregation of 69 RFLP (NTU) and 102 RAPD loci in 99 F₂ plants from the cross N. plumbaginifolia×N. longiflora. The map consists of nine major linkage groups, each containing more than nine marker loci, and spans 1062 cM. Twenty of the RFLP markers were mapped previously to Nicotiana sylvestris (2n=2x=24) chromosomes using monosomic alien addition lines.