Roselló Paula L, Vigliocco Ana E, Andrade Andrea M, Riera Natalí V, Calafat Mario, Molas María L, Alemano Sergio G
Laboratorio de Fisiología Vegetal, Fac. de Agronomía, Universidad Nacional de La Pampa (UNLPam), 6300, La Pampa, Argentina.
Laboratorio de Fisiología Vegetal, Fac. de Ciencias Exactas, Físico-Químicas y Naturales, Universidad Nacional de Río Cuarto (UNRC), 5800, Río Cuarto, Córdoba, Argentina.
Plant Physiol Biochem. 2016 May;102:133-40. doi: 10.1016/j.plaphy.2016.02.021. Epub 2016 Feb 19.
Seed germination and dormancy are tightly regulated by hormone metabolism and signaling pathway. We investigated the endogenous content of abscisic acid (ABA), its catabolites, and gibberellins (GAs), as well as the expression level of certain ABA and GAs metabolic and signaling genes in embryo of dry and imbibed cypselas of inbred sunflower (Helianthus annuus L., Asteraceae) lines: B123 (dormant) and B91 (non-dormant). Under our experimental conditions, the expression of RGL2 gene might be related to the ABA peak in B123 line at 3 h of imbibition. Indeed, RGL2 transcripts are absent in dry and early embedded cypselas of the non-dormant line B91. ABA increase was accompanied by a significant ABA-Glucosyl ester (ABA-GE) and phaseic acid (PA) (two ABA catabolites) decrease in B123 line (3 h) which indicates that ABA metabolism seems to be more active in this line, and that it would be involved in the imposition and maintenance of sunflower seed dormancy, as it has been reported for many species. Finally, an increase of bioactive GAs (GA1 and GA3) occurs at 12 h of imbibition in both lines after a decrease in ABA content. This study shows the first report about the RGL2 tissue-specific gene expression in sunflower inbred lines with contrasting dormancy level. Furthermore, our results provide evidence that ABA and GAs content and differential expression of metabolism and signaling genes would be interacting in seed dormancy regulation through a mechanism of action related to embryo itself.
种子萌发和休眠受到激素代谢和信号通路的严格调控。我们研究了自交向日葵（菊科向日葵属，Helianthus annuus L.）品系B123（休眠）和B91（非休眠）干燥及吸胀瘦果胚中脱落酸（ABA）及其分解产物、赤霉素（GAs）的内源含量，以及某些ABA和GAs代谢及信号基因的表达水平。在我们的实验条件下，RGL2基因的表达可能与B123品系吸胀3小时时的ABA峰值有关。事实上，在非休眠品系B91的干燥和早期包埋瘦果中不存在RGL2转录本。在B123品系（3小时）中，ABA增加伴随着ABA - 葡萄糖酯（ABA - GE）和相酸（PA）（两种ABA分解产物）显著减少，这表明该品系中ABA代谢似乎更活跃，并且它可能参与向日葵种子休眠的建立和维持，正如许多物种所报道的那样。最后，在ABA含量下降后，两个品系在吸胀12小时时生物活性GAs（GA1和GA3）均增加。本研究首次报道了向日葵自交系中具有不同休眠水平的RGL2组织特异性基因表达。此外，我们的结果提供了证据，表明ABA和GAs含量以及代谢和信号基因的差异表达将通过与胚本身相关的作用机制在种子休眠调控中相互作用。
