Potassium deficiency had a significant effect on the growth, development and microRNA-mediated mechanism in wheat (Triticum aestivum L.)

Abstract

Potassium is a crucial nutrient in the growth and development of plants and lack of available potassium was found to have significant affects in altering the morphology and gene expression of wheat. Wheat plants were grown from seeds in nutrient rich solutions, one with a standard concentration of potassium and one completely deficient in potassium. Root morphology of wheat was analyzed by comparing root volume, diameter, area, length, and branching zones. Dry biomass was recorded to compare root and shoot growth. Leaf and root respiration data was collected by measuring oxygen consumption of various samples. Root vitality measurements were gathered with a fluorescent analyzer at 485nm, but no significant results were found. Chlorophyll content was measured via spectrophotometry at 645nm and 663nm wavelengths. Gene expression of numerous miRNAs and target genes was measured and analyzed with qRT-PCR. Potassium deficiency resulted in a reduction in biomass and size of seedlings that was significant in shoots but had minimal influence on root vigor and biomass. The roots of potassium deficient plants, however; did suffer significant effects on root development. The emergence of seminal roots was delayed but had enhanced root length at a later time point. Increased total root surface area was also observed in potassium deficient samples along with extended non-branching zones. Results of gene expression analysis indicated that potassium deficiency altered the expression of many miRNAs and their target genes, allowing for the study of gene expression changes in response to abiotic stress. The changes in gene expression, when compared with alterations in wheat morphology and physiology, offer new insight into the actions and mechanisms of miRNA mediated gene regulation.