Isolation of a LEAFY homolog from Populus tomentosa: expression of PtLFY in P. tomentosa floral buds and PtLFY-IR-mediated gene silencing in tobacco (Nicotiana tabacum)

Abstract

To understand the genetic and molecular mechanisms underlying floral development in Populus tomentosa, we isolated PtLFY, a LEAFY homolog, from a P. tomentosa floral bud cDNA library. DNA gel blot analysis showed that PtLFY is present as a single copy in the genomes of both male and female individuals of P. tomentosa. The genomic copy is composed of three exons and two introns. Relative expression levels of PtLFY in tissues of P. tomentosa were estimated by RT-PCR; our results revealed that PtLFY mRNA is highly abundant in roots and both male and female floral buds. A low level of gene expression was detected in stems and vegetative buds, and no PtLFY-specific transcripts were detected in leaves. PtLFY expression patterns were analyzed during the development of both male and female floral buds in P. tomentosa via real-time quantitative RT-PCR. Continuous, stable and high-level expression of PtLFY-specific mRNA was detected in both male and female floral buds from September 13th to February 25th, but the level of PtLFY transcripts detected in male floral buds was considerably higher than in female floral buds. Our results also showed an inverted repeat PtLFY fragment (PtLFY-IR) effectively blocked flowering of transgenic tobacco plants, and that this effect appeared to be due to post-transcriptional silencing of the endogenous tobacco LFY homologs NFL1 and NFL2.

Isolation and expression analysis of a LEAFY/FLORICAULA homolog and its promoter from London plane (Platanus acerifolia Willd.)

“…In London plane, during the first season PlacLFY is expressed in the lateral meristems giving rise to inflorescence and in the developing inflorescence meristems from May to June. It is consistent with the inflorescence development process, which indicates that PlacLFY is involved in regulating inflorescence initiation and development in London plane, similar to LFY homologs in other plants (Ahearn et al 2001;An et al 2011;Coen et al 1990;Guo and Yang 2008;Molinero-Rosales et al 1999;Weigel et al 1992). Furthermore, floral primordium initiation in London plane begins late in June, and then floral organs initiate in Fig.…”

Identification and expression analysis of APETALA1 homologues in poplar

“…From September to November, the PtAP1-1 and PtAP1-2 mRNA were higher in female floral buds suggesting that a higher level of PtAP1-1 and PtAP1-2 mRNA is necessary to archespore formation in female flowers. A previous study reported that the level of expression of PtLFY (another floral meristem identity gene in P. tomentosa) in male floral buds was higher than that in female floral buds at different developmental stages from floral bud initiation to maturity (An et al 2011a, b). PtAP1-1 and PtAP1-2 reached a peak in expression three months before in male floral buds than in female floral buds.…”

“…Relative expressions of all transcripts were calculated using the 2 -DDCt method (Livak and Schmittgen 2001). The results obtained for the different tissues and stages we analyzed were standardized to the levels of a poplar ACTIN gene, which have stable expression in different tissues and in different developmental stages (An et al 2011a, b).…”

“…However, the long juvenile phase in poplars presents a substantial obstacle to research and breeding. Additionally, shed flowers, allergenic properties of poplar pollen, and catkin production represent sources of environmental pollution and a hazard to human health (An et al 2011a, b;Strauss et al 1995). The ability to control the transition from the juvenile phase to the reproductive phase and identification of the key genes involved in flowering in poplar would represent a significant accomplishment.…”

Short Communication Development of universal primers for isolating fragments of the LEAFY gene

“…In these studies, LEAFY gene homologs were mostly isolated from a cDNA library (An et al, 2011), which was both a time-consuming and an expensive process. Furthermore, a set of degenerate primers was designed for all plants, except algae, and the procedure for polymerase chain reactions (PCRs) of sequences with especially high GC contents was optimized.…”