Abstract
The proposed spectral control of the adaptive metabolic responses to drought was tested by the comparison of two wheat genotypes with different stress tolerance. White light was used as the reference to see the effects of the three altered ratios of blue, red, and far-red spectral components, which conditions are referred to as blue, pink, and far-red lights. Under all spectral conditions, drought greatly reduced the growth of both genotypes. However, the glutathione content decreased and the proline level increased, independently of the spectrum, only in the sensitive genotype. Far-red light greatly decreased the amount of cystine and glutathione disulphide during the stress which resulted in their lower ratios compared to the reduced forms only in the tolerant genotype. The maintained more reducing redox environment contributes to its better stress tolerance. In far-red light, drought induced a greater accumulation of several free amino acids (mHis, Val, Ile, Leu, Asn, His, Tyr, Lys, Arg) in the tolerant genotype, while a smaller one in the sensitive genotype compared to the other spectral conditions. The transcript level of the genes related to amino acid and glutathione metabolism was also different between the two genotypes under this condition. The present results indicate the adaptive adjustment of glutathione and amino acid levels by far-red light during drought which observation can serve as a basis for the spectrum-dependent modification of the protective metabolites (glutathione, proline) of crops to reduce the stress-induced damages.
Highlights
In nature, light spectrum is subjected to temporal and spatial changes as indicated by the greater ratio of blue light with increasing latitude and altitude and the lower red/farred (R/FR) ratio at higher latitude and during sunset (Kotilainen et al 2020)
The modification of spectral composition did not effect this parameter compared to white light in Plainsman, while it was greater in far-red light both during drought and recovery and smaller in blue light in Cappelle Desprez
The dry weight of the two species was not affected by drought, but it increased during the subsequent recovery period except for Cappelle Desprez in farred light where the increase was detected during drought (Table S3)
Summary
Light spectrum is subjected to temporal and spatial changes as indicated by the greater ratio of blue light with increasing latitude and altitude and the lower red/farred (R/FR) ratio at higher latitude and during sunset (Kotilainen et al 2020). In flag leaves of wheat, decrease in R/FR and increase in red/blue ratios enhanced the amount of several free amino acids (Monostori et al 2018) These biochemical changes affect the growth and development of plants (Lakshmanan et al 2015) as shown by the negative effect of blue light on growth in Scots pine (Taulavuori et al 2005) and by the positive influence of low R/FR ratio on the elongation process in Chrysanthemum morifolium and Phaseolus vulgaris (Lund et al 2007; Bartoli et al 2009). Both antioxidants and certain free amino acids have important role in the stress response; the light spectrum-dependent control of their levels is probably involved in the reduction of droughtinduced damages
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
