I want to know whether can we use inhibitors for certain specific group of genes like HSPs, to study their role in abiotic factors apart from validating the gene on heterologous expression system. Although, in case of animal system these inhibitors are widely used, but can we use it in non-modal plant system.
I would really appreciate if any information is provided.
Thanks
Hi,
if specific inhibitors are available these may be used, however whether these will affect any other physiological parameter needs to be assessed in any system
Hello Romit
The answer is yes. An example is given below. An antisense RNA to a photosynthetic enzyme reduced the enzyme activity very specifically and the effect on the rate of photosynthesis at different light fuxes could be observed. The full paper is available n Researchgate.
The Plant Journal (1995) 7(4), 535-542 Reduction in phosphoribulokinase activity by antisense RNA in transgenic tobacco: effect on CO2 assimilation and growth in low irradiance Matthew J. Paul 1o*, Jacqui S. Knight 2,t, Dimah Habash 1, Martin A.J. Parry 1, David W. Lawlor 1, Simon A. Barnes 2, Andy Loynes 2 and John C. Gray 2 1 Biochemistry and Physiology Department, IACRRothamsted, Harpenden, Herts AL5 2JQ, UK, and 2 Department of Plant Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EA, UK control coefficient for COz assimilation of zero, and that even when amounts of PRK are reduced 20-fold relative to wild-type, altered amounts of metabolites compensate for much of the reduction in PRK protein; (ii} in plants where there is a 95% reduction in amounts of PRK, photosynthesis was reduced twofold without large changes in leaf protein content or leaf geometry. Summary To quantify the importance of the Calvin cycle enzyme phosphoribulokinase (PRK} in photosynthesis and to perturb photosynthesis without large direct reductions in leaf protein content, tobacco plants (Nicotiana tabacum L.) were transformed with an inverted cDNA encoding tobacco PRK. A population of plants expressing antisensa RNA and a range of PRK activities from wild-type to less than 5% of wild-type were obtained. CO2 assimilation under the growing conditions (330 Ilmol photons m -2 sec -1, 350 I~bar CO 2, 25°C) was not inhibited until more than 85% of PRK activity had been removed. With reduction in PRK activity of between 85 and 95%, assimilation rates and amounts of chlorophyll compared with wild-type were reduced by up to half. Decreased absorption of light by leaves with less chlorophyll accounted for only a small part of the reduction in assimilation rate. When PRK activity was below 15% of wild-type, amounts of ribulose5-phosphate, ribosa-5-phosphate, ATP and fructose-6- phosphate were 1.5- to fivefold higher and levels of ribuIose-l,5-bisphosphate, 3-phosphoglyceric acid and ADP 1.5- to fourfold lower than in wild-type. It is estimated that these changes maintained flux through PRK to realise the assimilation rates observed. A possible shift of control within the Calvin cycle towards fructose-l,6-bisphosphatase in plants with low PRK is discussed. Amounts of hexoses and starch in particular were reduced in plants expressing the lowest PRK activities; amounts of sucrose were little affected. Lower CO 2 assimilation in plants with low PRK activity correlated with reduced relative growth rate of shoots and delayed flowering, but there was no effect on specific leaf area. It is concluded that (i) in wildtype plants grown in constant low light, PRK has a fluxR
Thank you very much David for sharing this useful information.
I have two distinct accessions exhibiting extreme tolerance and sensitive response. So, Here I want to find whether some stress associated factors can be used to assess such type of contrasting response. Although I have figured out some key genes from RNA Seq data and want to do some functional validation.
While going through some research articles, I came to know about certain inhibitors such as 'Geldanamycin' which is known to inhibit wide range of Heat shock Proteins in rice. So, Whether performing leaf disc assay followed by physiological parameters and expression quantification of specific gene can be useful, or I have to go for transgenic approach which is quite difficult in non-modal plant species.
Thanks
Romit
Hello Romit, My response was not really very closely related to your original question. It might be that an inhibitor with a known function, even if not specifically inhibiting a particular gene and stopping a given reaction, provides considerable useful information. That will depend on what is measured. You did not say what your two distinct accessions are - species, known differences etc. It would be useful to know what they differ in response to.
Regards David
Dear David,
Thank you so much for the kind response, actually my accessions belongs to the same species but exhibit differential contrasting response to heat and drought stress.
Kind Regards,
Romit
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