PI: Ravishankar Palanivelu; Co-PIs: Yitshak Zohar and Linan Jiang IOS-1045314 Title: EAGER-Interdisciplinary Collaborative Research: A high throughput, quantitative analysis of Arabidopsis pollen tube guidance using a novel microsystem-based assay During plant reproduction, signals from female tissues (pistils) guide the sperm-carrying pollen tube to the egg cell to achieve fertilization and initiate seed development. Essential for production of many crops, including all grains and fruits, this signaling process is still poorly understood. This project will develop next-generation microdevices that are necessary for identifying pollen tube guidance signals in the model plant Arabidopsis thaliana. Existing pollen tube guidance bioassays are not sensitive enough to detect the signals that are likely produced in minute quantities by pistils. Consequently, despite extensive research, the pistil signals that mediate this essential process remain elusive. Microdevices have been used in numerous biological applications, can realize 3-D structures ranging from 1-1000 micrometers and can amplify hard to detect biological signals. Thus, microsystem technology represents a radically different approach to replicate the complex configuration of the pistil micro-environment and faithfully recapitulate pistil signal micro-gradients. In an interdisciplinary collaboration between engineers and biologists, this project will develop the first ever microsystem-based assay to identify pollen tube guidance signals. Microdevices will be designed and fabricated to resemble the in-planta micro-environment of A. thaliana fertilization and subsequently used to define chemotropic signals from pistils. Pollen tube guidance leads to successful fertilization and seed formation in plants, and identifying the guidance signals may aid in increasing seed yield and quality of crops essential for human nutrition. Consequently, the project could have a major global impact since seeds of crop plants supply nearly 80% of world's staple food. Furthermore, this project may spur development of automated microsystems for investigating plant cell-cell signaling at an unprecedented nano-scale resolution. This project will promote synergistic interactions between biologists and engineers; undergraduate students will carry out some of the experiments, and post graduate researchers will gain interdisciplinary scientific training.