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Plant Biochemistry and Molecular Genetics Laboratory

Head of laboratory: Dr. Jarunya Narangajavana

Department of Biotechnology
Faculty of Science
Mahidol University
Rama 6 Road, Phayathai, Bangkok 10400 , THAILAND

Tel : 66-2-2015319     Fax: 66-2-3547160
e-mail: scjnr@mahidol.ac.th
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Research topics:

1.   Plant functional genomics study in cassava (Manihot esculenta Crantz.) to improve starch quality and quantity for industrial applications.

2.   Biochemical and molecular genetics related to latex yield and stress response of rubber tree (Hevea brasiliensis L.).

3.   Environmental friendly-plant molecular farming.

4.   Epigenetic control: Implications for plant improvement.


Cassava's competitiveness as a source for starch may be enhanced through the genetic improvement of both tuber yield and the physicochemical properties of cassava starch; the latter being a function of the lengths and relative proportions of amylose and amylopectin polymers, the principle constituents of starch granules. A better understanding of the key metabolic pathways involved in cassava starch biosynthesis should greatly assist in this regard. The long-term objective of our research is to facilitate cassava cultivar development in three main areas: (1) starch yields, (2) starch amylose/amylopectin ratio, and (3) starch granule morphology. Towards this end, we propose to isolate and characterize cassava homologs of genes implicated in various processes affecting the formation and accumulation of starch. These processes include the conversion of assimilated carbon to sucrose in photosynthetic leaves, the transport of sucrose to storage organs via the phloem, the transition of sucrose to starch, and the subsequent degradation of starch into simple sugars. By incorporating a team of researchers from various institutions with different expertise, this research works can cover an extensive area in cassava biotechnology. Starch biosynthetic process will be approached from different levels: biochemical and molecular to field studies. By this approach, it is expected that the outcome of this research project should be extensive and can provide useful information and applications for improvement cassava biotechnology in Thailand .

Rubber tree:

Among many problems related to the development of rubber production, the relatively low rubber yield per area is the most serious problem in Thailand . This is both due to plantation of traditional rubber clones with relatively low yielding potential and poorly-adapted exploitation techniques, and increasingly to the expansion of two kinds of bark disease, leading to the reduction or total cessation of latex flow. “Tapping Panel Dryness” (TPD) is a physiological inner bark disorder linked to the stress of overexploitation, most often extending from the tapping cut, downwards to the bottom part of the trunk. This disease becomes more and more serious with the increasing age of the plantations. “Trunk Phloem Necrosis” (TPN), is an irreversible bark disease of complex origin, with inner soft bark tissues necrosis. The TPN disease is favored by adverse environmental conditions (soil and climate), especially in marginal areas (such in North-East of Thailand ), by anthropogenic stresses (methods of planting and exploitation), and probably by some physiological rootstock-scion incompatibility. At the early stage of these bark diseases, it is impossible to discriminate between TPD and TPN, and therefore to give in time the adapted recommendations to the planters. These bark diseases become more and more important in plantations, and often seriously affect the rubber yield, as most of the plants are no longer tapped. It is therefore necessary to set up biochemical or molecular diagnosis tools, and to select or even create new rubber clones exhibiting low sensitivity to these diseases.
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