Departamento de Biologia Geral, Universidade Estadual de Montes Claros, Montes Claros, 39.401-089, Brazil.
Physiol Plant. 2015 Apr;153(4):627-42. doi: 10.1111/ppl.12269. Epub 2014 Nov 6.
Little is known about the control exerted by hormones in specific tissues during germination and post-germinative development in monocot seeds, whose embryos have complex structures and can remain dormant for long periods of time. Here the tissue-specific hormonal profile of macaw palm (Acrocomia aculeata) seeds overcoming dormancy and seedling during initial development was examined. Endogenous hormonal concentrations were determined in the cotyledonary petiole, haustorium, operculum, endosperm adjacent to the embryo and peripheral endosperm of dry dormant seeds, imbibed seeds trapped in phase I of germination, and germinating (phase 2 and phase 3) seeds 2, 5, 10 and 15 days after sowing. Evaluations were performed on seeds treated for overcoming dormancy by removal of the operculum and by immersion in a gibberellic acid (GA3 ) solution. Removal of the operculum effectively helped in overcoming dormancy, which was associated with the synthesis of active gibberellins (GAs) and cytokinins (CKs), as well as reductions of abscisic acid (ABA) in the cotyledonary petiole. In imbibed seeds trapped in phase I of germination, exogenous GA3 caused an increase in active GAs in the cotyledonary petiole and operculum and reduction in ABA in the operculum. Initial seedling development was associated with increases in the CK/auxin ratio in the haustorium and GA levels in the endosperm which is possibly related to the mobilization of metabolic reserves. Increases in salicylic acid (SA) and jasmonic acid (JA) concentrations were associated with the development of the vegetative axis. Hormones play a crucial tissue-specific role in the control of dormancy, germination and initial development of seedlings in macaw palm, including a central role not only for GAs and ABA, but also for CKs and other hormones.
关于激素在单子叶种子萌发和萌发后发育过程中对特定组织的控制作用知之甚少，单子叶种子的胚结构复杂，并且可以长时间休眠。在这里，我们研究了克服鹦鹉棕榈（Acrocomia aculeata）种子休眠和幼苗在初始发育过程中休眠的组织特异性激素特征。在子叶叶柄、吸器、种皮、胚乳相邻的胚乳和干休眠种子的外周胚乳、吸胀种子（处于萌发的 I 期）、发芽种子（第 2、5、10 和 15 天播种后）中测定内源激素浓度。通过去除种皮和浸泡在赤霉素（GA3）溶液中对种子进行休眠处理，然后对种子进行评估。去除种皮可有效帮助克服休眠，这与活性赤霉素（GAs）和细胞分裂素（CKs）的合成以及子叶叶柄中脱落酸（ABA）的减少有关。在处于萌发的 I 期的吸胀种子中，外源 GA3 导致子叶叶柄和种皮中的活性 GAs 增加，种皮中的 ABA 减少。初始幼苗发育与吸器中 CK/生长素比和胚乳中 GA 水平的增加有关，这可能与代谢储备的动员有关。水杨酸（SA）和茉莉酸（JA）浓度的增加与营养轴的发育有关。激素在鹦鹉棕榈种子休眠、萌发和幼苗初始发育的组织特异性控制中发挥着至关重要的作用，包括 GA 和 ABA 不仅起中心作用，而且 CK 和其他激素也起作用。
