THE EXPANSIN EXP1 GENE IN THE ELONGATION ZONE IS INDUCED DURINGSOYBEAN EMBRYONIC AXES GERMINATION AND DIFFERENTIALLYEXPRESSED IN RESPONSE TO ABA AND PEG TREATMENTS

MONTECHIARINI, NIDIA H.; DELGADO, LUCIANA; MORANDI, ELIIGIO N.; CARRILLO, NESTOR; GOSPARINI, CARLOS

SEED SCIENCE RESEARCH

CAMBRIDGE UNIV PRESS

Lugar: Cambridge; Año: 2020

0960-2585

During soybean seed germination, theexpansive growth potential of the embryonicaxesis driven by water uptake while cell wall loosening occurs in cells from theelongation zone (EZ). Expansins are regardedas primary promoters of cell wallremodelingin all plant expansion processes, with the expression profiles of thesoybean expansins supporting their cell ortissue specificity. Therefore, we usedembryonicaxes isolated from whole seed and focused the molecular analyses on theEZ to study seed germination. Using a suiteof degenerate primers, we amplified anabundantlyexpressed expansin gene at the EZ during soybean embryonic axesgermination, which was identified as EXP1 byin silico analyses. Expression studiesshowedthat EXP1 was induced under germination conditions in distilled water anddown-regulated by abscisic acid (ABA), whichinhibits soybean germination byphysiologicallyrestraining expansion. Moreover, we also identified a time window ofABA responsiveness within the first sixhours of incubation in water, after which ABAlostcontrol of both EXP1 expression and embryonic axes germination, thus confirmingthe early role of EXP1 in the EZ during thisprocess. By contrast, EXP1 levels in the EZincreasedeven when germination was impaired by osmotically limiting the wateravailability required to develop theembryonic axes ́ growth potential. We propose thatthese higher EXP1 levels would be involvedin the fast germination of soybeanembryonicaxes as soon as water availability was reestablished. Taken together, ourresults show strong EXP1 expression in theEZ and postulate EXP1 as a targetcandidatefor soybean seed germination control.