SOYBEAN SEEDS GERMINATION: THE ROLE OF STORED mRNA

MONTECHIARINI H. NIDIA; DELGADO LUCIANA; PALMIERI, REGINA; SARCHIONI, F; ARAUJO, A; CERVIGNI, N; CARRILLO, NESTOR; ELIGIO N. MORANDI; GOSPARINI, CARLOS

Congreso; XVII CONGRESS ? XXXV ANNUAL MEETING; 2015

Sociedad de Biología de Rosario

Seed developmentis controlled by specific molecular programs and both, in physiological matureseeds (PM) and in dry mature seeds (DM), a great quantity of mRNA is keptstored. In Arabidopsis thaliana, mRNAs stored in the dry mature seedsare sufficient for germination. We have demonstrated that the mRNA of anExpansin (EXP) is present among the stored transcripts on the embryo axis ofsoybean seeds (Glycine max L Merr.), and its level increases duringgermination. This EXP cause loosening and extension of cell walls in responseto the cell water uptake. The objective of this work was to determine ifsoybean seeds germinate in the absence of mRNA de novo synthesis, and tostudy the kinetics of germination. Soybean Embryo Axis of PM and DM wereincubated on either Distilled Water (DW), 100 μM of α-Amanitin (α-Am, transcriptional inhibitor) or100 μM of Cicloheximide (Cx, translationalinhibitor). Germination percentages (%G) and times to 50 %G (tG50) werecalculated. On DM, Accumulated Relative Weight to the initial weight (ARW) wasmeasured during incubation on DW and on α-Am. On DW, the100 %G was reached at 12 and 18 h in PM and DM, respectively; on α-Am, at 29 h in PM, whereas in DM it was only 87.5 %G at 48 h. On Cx,there was no germination in any case. The tG50 in PM were 6 and 25.5 h and, inDM, 9 and 33 h on DW and α-Am, respectively. The ARW on DW andon α-Am showed a similar increase during the first2 h (ARW=1.8); kept stable until 8 and 12 h on DW and on α-Am, respectively and finally, it increased faster on DW (ARW=7 at 72 h)than on α-Am (ARW=2.6 at 72 h). These results showedthat translation but not transcription is needed to germinate. However, therewas a delay in transcription absence which was higher for DM than for PM axis.The dehydration process could modify the quantity or quality, or both, of thestored mRNAs. We postulate that the mRNA level of the EXP would be sufficientto germinate, and its de novo synthesis would be required to keep normalgermination rates.