Kudoyarova G R, Romanova A K, Novichkova N S, Vysotskaya L B, Akhtyamova Z, Akhiyarova G R, Veselov S Y, Ivanov B N
a Ufa Institute of Biology, Ufa Research Centre , Russian Academy of Sciences , Ufa , Russia.
b Institute of Basic Biological Problems , Russian Academy of Science , Pushchino , Russia.
Plant Signal Behav. 2018;13(6):e1482175. doi: 10.1080/15592324.2018.1482175. Epub 2018 Jun 26.
The level of hormones in the tissues of sugar beet leaves of different age in parallel with their growth and metabolic activity was assayed; the latter was analyzed, measuring the contents of sugars and N-containing compounds, and the activities of Rubisco and proteases. The highest auxin and ABA concentration was detected in the actively growing upper leaf, while high level of cytokinins was maintained in the middle and upper leaves characterized by intensive photosynthesis. Leaf senescence being manifested in decline of chlorophyll content, decrease of photosynthesis and activation of proteolysis was accompanied by a decline in concentration of cytokinins. Glucose level gradually increased from upper (younger) to a lower (elder) leaves; this was accompanied with the signs of senescence on the background of decreased cytokinins level. Immuno-histochemical technique revealed increased level of abscisic acid in phloem parenchyma of the lowest leaf. The results suggest a possible involvement of auxins in maintaining leaf growth, an implication of decreased cytokinins level in the hypothesized induction of senescence by glucose, and a participation of abscisic acid in the active loading of metabolites into the phloem of senescing leaf.
测定了不同年龄甜菜叶片组织中激素水平及其生长和代谢活性；通过测量糖和含氮化合物的含量以及核酮糖-1,5-二磷酸羧化酶（Rubisco）和蛋白酶的活性来分析后者。在生长活跃的上部叶片中检测到最高的生长素和脱落酸浓度，而在以强烈光合作用为特征的中部和上部叶片中保持高水平的细胞分裂素。叶片衰老表现为叶绿素含量下降、光合作用降低和蛋白水解激活，同时伴随着细胞分裂素浓度的下降。葡萄糖水平从上部（较年轻）叶片到下部（较老）叶片逐渐升高；在细胞分裂素水平降低的背景下，这伴随着衰老迹象。免疫组织化学技术显示最低叶片韧皮部薄壁细胞中脱落酸水平升高。结果表明生长素可能参与维持叶片生长，细胞分裂素水平降低可能与葡萄糖诱导衰老的假说有关，脱落酸参与衰老叶片中代谢物向韧皮部的主动装载。
