Phloem Unloading of C and N Assimilates in Developing Seeds

INTRODUCTION . . . . . . 317 PATHWAY OF ASSIMILATE IMPORT 318 Role of Maternal Tissues ...... .... 318 Structural Aspects of Unloading . ...... . . . . .. .. .. . . ....... . . ..... .. 319 CHARACTERISTICS OF PHLOEM UNLOADING. .. .... . . . . .. .. . . . . . . .. . . . . . . . .... . .. . . . . . . 329 Development of the Empty Seed Coat Techni que 329 Kinetics of Assimilate Delivery 330 Solute Transformations during Delivery 332 Ener gy-Dependent Unloading 333 The Nature of Os moti c Effects 336 SUMMARy. . . . . . . . . .. ....... . . . . ... . . . . . .. . . . . . . . . . . . . . .. . ... . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . ..... . . . ... 339