PROTEOMIC ANALYSIS AND PHYSIOLOGICAL RESPONSE OF WHEAT TREATED WITH A TRIGLYCERIDE PURIFIED FROM LUPINUS ALBUS L. SEED

• Main Author: Viljoen, Riana
• Other Authors: Prof JC Pretorius
• Format: Others
• Language: en-uk
• Published: University of the Free State 2014
• Subjects: Plant Sciences
• Online Access: http://etd.uovs.ac.za//theses/available/etd-08212014-141230/restricted/

The agricultural use of bio-stimulants to increase crop yield is increasing as a result of the ever growing human population. Since bio-stimulants do not have the negative environmental effects usually associated with fungicides and pesticides, the identification and testing of new bio-stimulants are a priority. It was previously shown that treatment of wheat cultivar PAN 3377 with a crude Lupinus albus L. seed suspension extract increased the yield compared to an untreated control. The agricultural use of bio-stimulants to increase crop yield is increasing as a result of the ever growing human population. Since bio-stimulants do not have the negative environmental effects usually associated with fungicides and pesticides, the identification and testing of new bio-stimulants are a priority. It was previously shown that treatment of wheat cultivar PAN 3377 with a crude Lupinus albus L. seed suspension extract increased the yield compared to an untreated control. During the current study, the bio-stimulatory effect of a 60% purified extract called SS was investigated. The initial aim was to analyse the effect of the purified SS extract on yield of the wheat cultivar Thatcher+Lr34. No significant increases in yield or any of the associated parameters were obtained in response to SS treatment. This indicated that, while the crude and complex SS extract increased yield in wheat, the purified molecule was unable to do it. To validate the glass house results, proteomic analysis of SS treated wheat cultivar Thatcher+Lr34 was done. Results indicated that the purified SS extract mainly targets the photosynthetic machinery of the plant by altering three main pathways. While the levels of polypeptides active in both the Calvin cycle and electron transport chain were generally down-regulated following treatment, a few polypeptides involved in the PSII and general repair mechanisms, were up-regulated. These results were validated by qPCR analysis of three randomly selected genes from each of the mentioned pathways. When wheat cultivar Tugela was treated with the 60% pure SS extract and exposed to heat stress, a stabilising effect on chloroplast ultrastructure was observed. Thylakoid membranes were intact and no induction of the membrane stabilising gene OEE2 was observed. However, when infected with RWA, the 60% pure SS extract was unable to facilitate chloroplast membrane stabilisation. This was supported by the induced expression of both the OEE2 and HCF136 genes. This study concludes that the 60% pure SS extract, of which glycerol trilinoleate is the active ingredient, cannot be used as a bio-stimulant independently. It is proposed that during the purification of the crude SS extract, additional components responsible for increasing yield in wheat, was lost and thereby its ability to increase yield. This product could however be of value when used in combination with other compounds that is able to facilitate yield increases.