Mellerowicz E J, Horgan K, Walden A, Coker A, Walter C
Biotechnology Division, Forest Research Institute, Rotorua, New Zealand.
Planta. 1998 Nov;206(4):619-29. doi: 10.1007/s004250050440.
In angiosperms, the formation of the flower meristem is controlled by partially redundant flower meristem identity genes of which FLORICAULA (FLO)/LEAFY (LFY) plays a central role. It is not known whether formation of reproductive organs of pre-angiosperm species is similarly regulated. Recently, a FLO/LFY-like cDNA, NEEDLY (NLY), has been cloned in a conifer species Pinus radiata (D. Don). Here we report cloning of a different Pinus radiata FLO/LFY-like cDNA, PRFLL. PRFLL had two large regions of high similarity to angiosperm FLO/LFY orthologues: amino acids 61-126 and 247-406 (50% and 81% identity, and 75% and 88% similarity, respectively, to LFY) and shorter regions of local similarity. Overall identity was 53% to LFY and 61% to NLY. Phylogenetic analysis of deduced protein sequences including partial LFY-like sequences from Pseudotsuga menziesii indicated that conifer proteins constituted a separate clade that could be divided into two groups represented by NLY and PRFLL. In contrast to angiosperms, both conifers had two paralogous proteins resembling LFY. Northern hybridisation analysis revealed expression of PRFLL in vegetative buds of juvenile, adolescent and mature trees. The transcript was not detected in vascular cambium, roots or secondary needles. To follow PRFLL expression during the early stages of cone development we analysed a temporal series of buds containing cone primordia, and developing cones, using Northern hybridisation and confocal microscopy in parallel. PRFLL mRNA was detected in buds from dominant and subordinate branches, in which cone and shoot primordia develop, and in developing male cones but not in developing female cones. Expression was particularly high in buds containing axillary primordia prior to their differentiation as male cone primordia. This is consistent with PRFLL being involved in determination of the male cone primordium identity.
在被子植物中，花分生组织的形成受部分冗余的花分生组织特性基因控制，其中花椰菜（FLO）/叶状（LFY）基因起核心作用。目前尚不清楚被子植物之前的物种其生殖器官的形成是否受到类似调控。最近，在一种针叶树辐射松（D. Don）中克隆到了一个类似FLO/LFY的cDNA，即NEEDLY（NLY）。在此，我们报道了另一个辐射松类似FLO/LFY的cDNA，即PRFLL的克隆。PRFLL有两个与被子植物FLO/LFY直系同源基因高度相似的大区域：氨基酸61 - 126和247 - 406（分别与LFY的同一性为50%和81%，相似性为75%和88%）以及局部相似性的较短区域。与LFY的总体同一性为53%，与NLY的为61%。对推导的蛋白质序列进行系统发育分析，包括来自北美云杉的部分类似LFY的序列，结果表明针叶树蛋白质构成一个单独的进化枝，可分为以NLY和PRFLL为代表的两组。与被子植物不同，两种针叶树都有两个类似LFY的旁系同源蛋白。Northern杂交分析显示PRFLL在幼年、青年和成熟树木的营养芽中表达。在维管形成层、根或次生针叶中未检测到该转录本。为了追踪PRFLL在球果发育早期阶段的表达，我们同时使用Northern杂交和共聚焦显微镜分析了一系列含有球果原基和发育中球果的芽的时间序列。在优势枝和从属枝的芽中检测到PRFLL mRNA，在这些芽中球果和茎原基发育，在发育中的雄球果中也检测到，但在发育中的雌球果中未检测到。在含有腋生原基且尚未分化为雄球果原基的芽中，表达特别高。这与PRFLL参与雄球果原基特性的决定是一致的。
