Brunel Nicole, Leduc Nathalie, Poupard Pascal, Simoneau Philippe, Mauget Jean-Claude, Viémont Jean-Daniel
INH, UMR SAGAH A462, 2, rue Le Nôtre, F-49045 Angers Cedex 01, France.
J Exp Bot. 2002 Nov;53(378):2143-9. doi: 10.1093/jxb/erf063.
The determinism of bud bursting pattern along the 1-year-old shoot was studied at the molecular and morphological levels in the apple tree variety 'Lodi' which shows an acrotonic tendency. At the molecular level, the expression of KNAP2, which belongs to the class I KN1-like gene family, was studied. Measurements were carried out during dormancy (October), breaking dormancy (January) and just before bud bursting (March). The results showed that KNAP2 is more highly expressed in buds that will remain at rest in the spring. Expression of KNAP2 was found in the meristem and in the marginal meristem of the two latest shaped primordia. In the January and March buds, this gene is also expressed in the procambial zone underneath the apical meristem. This study therefore suggests that KNAP2 may be considered as a negative marker of bud growth potential and that the growth inhibition in proximal buds could partially result from differential gene activity. At the morphological level, it was shown that no organogenetic activity took place between October and March as revealed by the constant number of leaf primordia in buds. Nevertheless, those buds likely to grow the following spring had a larger size and fewer hard scales than other buds. This suggests that genetic control may act together with other mechanisms, possibly physical (number of scales) or biochemical, to control bud inhibition.
在具有顶端优势倾向的苹果品种‘洛迪’中，从分子和形态学水平研究了一年生枝条上芽萌发模式的决定因素。在分子水平上，研究了属于I类KN1-like基因家族的KNAP2的表达。在休眠期（10月）、休眠解除期（1月）和芽萌发前（3月）进行了测量。结果表明，KNAP2在春季仍处于休眠状态的芽中表达更高。在分生组织以及两个最新形成的原基的边缘分生组织中发现了KNAP2的表达。在1月和3月的芽中，该基因也在顶端分生组织下方的原形成层区域表达。因此，这项研究表明，KNAP2可被视为芽生长潜力的负标记，近端芽的生长抑制可能部分源于基因活性的差异。在形态学水平上，研究表明，10月至3月期间芽内叶原基数量恒定，未发生器官发生活动。然而，那些次年春天可能生长的芽比其他芽更大，硬鳞片更少。这表明遗传控制可能与其他机制共同作用，可能是物理机制（鳞片数量）或生化机制，以控制芽的抑制。
