Puga-Hermida María Isabel, Gallardo Mercedes, Rodríguez-Gacio María Del Carmen, Matilla Angel J
Departamento de Biología Vegetal y Ciencias del Suelo, Laboratorio de Fisiología Vegetal, Facultad de Ciencias, Universidad de Vigo, E-36200-Vigo, Pontevedra, Spain.
Departamento de Biología Vegetal, Laboratorio de Fisiología Vegetal, Facultad de Farmacia, Universidad de Santiago de Compostela, 15706 Santiago de Compostela, A Coruña, Spain.
Funct Plant Biol. 2003 Aug;30(7):767-775. doi: 10.1071/FP03053.
The mature silique of turnip-tops (Brassica rapa L. cv. Rapa) contains seeds that are heterogeneous in colour. From these seeds, we have selected three homogeneous lots: black (B), dark brown (DB) and light brown (LB). The dry seeds of these lots contained different levels of free and conjugated 1-aminocyclopropane-1-carboxylic acid (ACC), polyamines (PA) and ABA, the levels of the latter being inversely related to the germinative capacity. The water uptake (WU) rate was much faster in LB seeds than in B. This fact was probably related to the breaking of the seed coat, the speed of which was B >> DB > LB. The ABA, spermidine (Spd) and spermine (Spm) contents decreased in the seeds during germination, whereas the putrescine (Put) levels rose sharply (B > DB > LB). For the first time in seeds, heterogeneity is reported with respect to ethylene sensitivity and synthesis. Whereas exogenous ethylene did not alter the percentage of germination in lot B, germination was higher in DB and LB (LB>> DB) in the presence of ethylene. The final step of the ethylene pathway was altered concomitantly with this change in germinating capacity, affecting the levels of 1-(malonylamino)cyclopropane-1-carboxylic acid (MACC), ACC, ACC-oxidase (ACO) and ethylene production. The gene BrACO1, recently characterised by us, is expressed differently in the three seed lots, particularly in the LB, where little transcription occurs. Finally, ethylene inhibits Put, Spd and Spm levels at different intensities in the three lots. The results point towards variation in the channelling of ACC towards synthesis of ethylene and / or PA, caused by the heterogeneity.
芜菁叶（芜菁甘蓝变种拉帕）的成熟角果包含颜色各异的种子。从这些种子中，我们挑选出了三个同质批次：黑色（B）、深褐色（DB）和浅褐色（LB）。这些批次的干种子含有不同水平的游离和结合态1-氨基环丙烷-1-羧酸（ACC）、多胺（PA）和脱落酸（ABA），其中ABA的水平与发芽能力呈负相关。LB种子的吸水（WU）速率比B种子快得多。这一事实可能与种皮的破裂有关，种皮破裂速度为B >> DB > LB。种子在萌发过程中ABA、亚精胺（Spd）和精胺（Spm）含量下降，而腐胺（Put）水平急剧上升（B > DB > LB）。首次报道了种子在乙烯敏感性和合成方面存在异质性。外源乙烯不会改变B批次种子的发芽率，而在乙烯存在下，DB和LB批次种子的发芽率更高（LB>> DB）。乙烯途径的最后一步与发芽能力的这种变化同时改变，影响了1-（丙二酰氨基）环丙烷-1-羧酸（MACC）、ACC、ACC氧化酶（ACO）和乙烯产生的水平。我们最近鉴定的基因BrACO1在三个种子批次中的表达不同，特别是在LB批次中，转录很少发生。最后，乙烯在三个批次中以不同强度抑制Put、Spd和Spm水平。结果表明，异质性导致ACC向乙烯和/或PA合成的通道发生变化。
