Methods for Assessing the Role of Phloem Transport in Plant Stress Responses.

Delivery of carbohydrates to tissues under stress is important for plant defenses, recovery, and survival. Yet, little is known on how phloem function is altered under stress, and how that influences plant responses to stress. This chapter summarizes current and emerging methods for quantifying phloem transport and assessing how environmental stress affects phloem function at whole plant scale. The techniques discussed range from isotopic and fluorescent tracer studies to advanced non-invasive imaging (MRI, NMR, and PET), carbon balance approaches, anatomical analysis, and stem diameter monitoring. Emphasis is placed on the methodological principles, experimental design, and applicability of each technique to stress studies.