Wang Da-Yong, Li Qing, Cui Ke-Ming, Zhu Yu-Xian
Key Laboratory of Developmental Genes and Human Disease in Ministry of Education, Nanjing 210009, China.
J Integr Plant Biol. 2009 Jan;51(1):13-20. doi: 10.1111/j.1744-7909.2008.00788.x.
G2 pea exhibits an apical senescence delaying phenotype under short-day (SD) conditions; however, the structural basis for its apical development is still largely unknown. In the present study, the apical meristem of SD-grown G2 pea plants underwent a transition from vegetative to indeterminate inflorescence meristem, but the apical meristem of long-day (LD)-grown G2 pea plants would be further converted to determinate floral meristem. Both SD signal and GA(3) treatment enhanced expression of the putative calcium transporter PPF1, and pea homologs of TFL1 (LF and DET), whereas LD signal suppressed their expression at 60 d post-flowering compared with those at 40 d post-flowering. Both PPF1 and LF expressed at the vegetative and reproductive phases in SD-grown apical buds, but floral initiation obviously increased the expression level of PPF1 compared with the unchanged expression level of LF from 40 to 60 d post-flowering. In addition, although the floral initiation significantly enhanced the expression levels of PPF1 and DET, DET was mainly expressed after floral initiation in SD-grown apical buds. Therefore, the main structural difference between LD- and SD-grown apical meristem in G2 pea lies in whether their apical indeterminate inflorescence meristem could be converted to the determinate structure.
G2豌豆在短日照（SD）条件下表现出顶端衰老延迟的表型；然而，其顶端发育的结构基础仍 largely未知。在本研究中，SD条件下生长的G2豌豆植株的顶端分生组织经历了从营养分生组织到无限花序分生组织的转变，但长日照（LD）条件下生长的G2豌豆植株的顶端分生组织会进一步转变为有限花分生组织。与开花后40天时相比，SD信号和GA(3)处理均增强了假定的钙转运蛋白PPF1以及TFL1的豌豆同源物（LF和DET）的表达，而LD信号在开花后60天时抑制了它们的表达。PPF1和LF在SD条件下生长的顶端芽的营养期和生殖期均有表达，但与开花后40至60天LF表达水平不变相比，花的起始明显增加了PPF1的表达水平。此外，虽然花的起始显著增强了PPF1和DET的表达水平，但DET主要在SD条件下生长的顶端芽的花起始后表达。因此，G2豌豆中LD和SD条件下生长的顶端分生组织之间的主要结构差异在于其顶端无限花序分生组织是否能转变为有限结构。
