Seeing is believing: imaging techniques to monitor plant health

Historically, early stress-induced changes in plants have been mainly detec ted after destructive sampling followed by biochemical and molecular determ inations. Imaging techniques that allow immediate detection of stress-situa tions, before visual symptoms appear and adverse effects become established , are emerging as promising tools for crop yield management. Such monitorin g approaches can also be applied to screen plant populations for mutants wi th increased stress tolerance. At the laboratory scale, different imaging m ethods can be tested and one or a combination best suited for crop surveill ance chosen. The system of choice can be applied under controlled laborator y conditions to guide selective sampling for the molecular characterisation of rapid stress-induced changes. Such an approach permits to isolate presy mptomatically induced genes, or to obtain a panoramic view of early gene ex pression using gene-arrays when plants undergo physiological changes undete cted by the human eye. Using this knowledge, plants can be engineered to be more stress resistant, and tested for field performance by the same method ologies. In ongoing efforts of genome characterisation, genes of unknown fu nction are revealed at an ever-accelerating pace. By monitoring changes in phenotypic characteristics of transgenic plants expressing those genes, ima ging techniques could help to identify their function. (C) 2001 Elsevier Sc ience B.V. All rights reserved.