COMPARATIVE-STUDY OF 2 CRYOTECHNIQUES TO ELUCIDATE REAL FUNCTIONAL-ASPECTS OF LEGUME NODULES DEVELOPMENT

Legume nodules from Lupinus albus L. cv. Multolupa and Phaseolus vulga ris L. cv. Tormesina plants were subjected to two different cryotechni ques (High Pressure Freezing, HPF and Fast Freeze Fixation, FFF) in or der to compare the structure obtained with respect to previous feature s and to deepen the relationships between the microsymbiont and the ho st cell in the native state. Comparing both cryotechniques, HPF yielde d better general nodule ultrastructure than FFF HPF allowed the observ ation of the nat ive nodule structure since it permitted an excellent preservation. The result obtained showed that the peribacteroidal memb rane was in close contact with the bacteroids, which is in contrast wi th the observations after chemical fixation. The narrow peribacteroid space observed between bacteroid and peribacteroid membranes appears a s a dense matrix which is in agreement with the former knowledge on th e existence of some enzymes and proteins in this space. O-2-released b y leghemoglobin will occur in close proximity to the bacteroid membran es. The spatial relationship between Golgi apparatus and ER with the p eribacteroidal membrane observed along the development of the nodule i ndicates that these structures are very much related with the formatio n of the symbiosome membrane. HPF could be the right technique to cont inue studying real functional aspects in developing nodules.