Analysis of gene expression in wheat upon treatment with a novel plant activator

Abstract

English: Plant activators are an exciting alternative to modern day plant pathogen control procedures. Yet research on plant activators and the mechanisms involved in their action remains limited. The plant activator used during this study, SS, is a purified fraction from the commercial product ComCat® with known positive effects in field trials. The main aims of the study was to confirm the action of SS on a molecular level in wheat, identify genes involved in the process and examine the possible mode of action of the activator. Leaf rust resistant Thatcher+Lr34 and susceptible Thatcher wheat cultivars were treated with SS and water. SSH was performed on pooled Thatcher+Lr34 RNA resulting in 562 putatively induced cDNA clones. Of these, 51 were sequenced. The sequenced clones shared homology with a variety of genes mostly encoding photosynthetic and metabolic products, as well as one plant defence related gene encoding Ptr ToxA binding protein1. Expression analysis confirmed a characteristic two step induction pattern in Thatcher+Lr34 confirming the induced gene expression It was concluded that SS application in wheat increases photosynthetic and metabolic capacity on a molecular level thereby confirming field results. The induction of expression of TaThf1 (Ptr ToxA Binding protein1) by SS suggested a possible unique role in plant defence against pathogens.

Afrikaans: Die gebruik van plantaktiveerders bied ‘n opwindende alternatief vir moderne tegnieke om plantpatogene te beheer. Ten spyte hiervan is baie min navorsing op die gebied van plantaktiveerders en hul meganismes tot dusver gedoen. ‘n Gesuiwerde fraksie van die kommersiële produk, ComCat®, bekend as SS, is as plantaktiveerder gebruik gedurende die studie, omdat dit positiewe resultate in veldproewe gelewer het. Die hoof doelwitte van hierdie projek was om die aksie van SS op molekulêre vlak in koring te ondersoek, om gene te identifiseer wat in die proses betrokke is asook om ‘n moontlike meganisme van werking vir SS daar te stel. Thatcher+Lr34, weerstandbiedend teen stamroes, en vatbare Thatcher plante is met SS en water behandel. Saamgepoelde RNA van Thatcher+Lr34 plante is tydens SSH gebruik. In totaal is 562 moontlik geïnduseerde cDNA klone geïdentifiseer. Die DNA basisvolgorde van 51 van die klone is bepaal. Die meerderheid van die klone het homologie op geen vlak getoon met gene wat vir fotosintetiese en metaboliese produkte kodeer. Een kloon het homologie met die geen wat kodeer vir Ptr ToxA bindingsprotiën1 wat betrokke is by plantverdediging getoon. Ten slotte is bewys dat behandeling met SS die fotosintetiese en metabolise kapasiteit van koring op molekulêre vlak verhoog. Die induksie van TaThf1 uitdrukking na SS behandeling dui ook op ‘n moontlike unieke rol van SS in plantverdediging.