| The present research aims to determine the relationship of cytokinin (CK) levels in barley kernels to kernel, mass kernel number, and plant yield. Early studies with barley found a positive relationship between CK content and kernel mass. However, recent work with rice suggests a connection between CKs and the number of grains produced, but no correlation of CK content to grain mass. With the advent of more sensitive and selective mass spectrometric techniques and established methods for extracting and purifying CKs, the roles of CKs in barley kernel development can be more precisely re-examined. To this end, CK profiles across early developmental stages have been generated for kernels of high-yield and low-yield barley varieties. Analysis and subsequent quantification was achieved by liquid chromatography-tandem mass spectrometry. Our results indicate that there is a relationship between CK concentration in kernels and increased plant yield. Importantly, this is the first field-based study linking endogenous CKs to yield. Furthermore, we also discuss the results of an investigation into the possible role for cytokinin oxidase (CKX) in regulation of CK levels in barley grains through the degradation of CKs.;Keywords: barley, cytokinins, cytokinin oxidase, yield, seed development... |
