TABLE CONTENTS

Functional Characterisation of Transcripts Expressed in Early Stage
Meloidogyne javanica-induced Giant Cells Isolated by Laser
Microdissection
Fosu-Nyarko, J., Z. Wang & M.G.K. Jones
Plant Biotechnology Research Group, Western Australian State Agricultural Biotechnology Centre (SABC),
Faculty of Sustainability, Environmental and Life Sciences, Murdoch University, Perth, Western Australia.
Meloidogyne javanica induces giant cells and feeds from them during its development and
reproduction. To study the cellular processes underlying the formation of giant cells, we used
laser capture and microdissection to isolate the contents of early stage giant cells 4 and 7 days
post infection (dpi), and generated cDNA libraries from mRNA from batches of 100 giant
cell samples. Eighty seven (250 EST clones) and 54 (309 EST clones) individual transcripts
were identified from the 4 and 7dpi libraries respectively. These have roles in metabolism,
stress response, protein synthesis, cell division and morphogenesis, transport, signal
transduction, protein modification and fate, and regulation of cellular processes. Expression
of 11 of 25 transcripts was upregulated in giant cells between the 4 th and 7 th day after
infection. For 4 genes expression was higher than controls at 4dpi and at 7dpi. Levels of
expression for another 4 genes increased only at 7dpi. Genes not affected by nematode
infection include phenylalanine ammonia lyase and MTD1, the product of the latter gene
accumulates in nodules in Medicago truncatula. Phi protein, a cell-cycle related homologue
in tobacco, expressed 8.5 times higher in giant cells than surrounding cells at 4dpi and
reduced to 6.7 times higher at 7dpi: it may be important in early stages of giant cell
formation. Together with a pectinesterase gene and a proteasome subunit beta type 2-A
involved in cell division and morphogenesis, Phi protein preferentially localises in cytoplasm
of giant cells at about 5dpi. The identification of highly expressed transcripts in developing
giant cells adds to knowledge of genes responsive to nematodes. Characterisation of
transcripts matching unknown proteins, and cDNAs with no significant matches in gene
databases, will increase understanding of nematode-host interactions, and may provide
candidate genes and/or promoters which could be used in nematode control strategies.
5 th International Congress of Nematology, 2008 249