Use of different seed tissues for separate biparentage identification of dispersed seeds in conifers: confirmations and practices for gene flow in Pinus densiflora

Abstract

To investigate how accurately biparentage assignments for coniferous seeds can be improved by using different kinds of seed tissues, we assigned biparentage to dispersed seeds in a natural stand of Pinus densiflora Siebold & Zucc. (288 mature trees) using two procedures: with or without megagametophyte haplotype data (“MH” and “ordinary” procedures, respectively). Using archived clones, we confirmed the conifer-specific modes of inheritance of three kinds of seed tissues from certain maternal trees using six microsatellite markers. In the natural stand, under the MH procedure, 39.2% of male parents and 77.0% of female parents for a total of 204 seeds analyzed were assigned to at least one mature tree within the study area. At that time, the proportion of exactly matching seeds out of seeds with one matching parent under the MH procedure was significantly larger than that of the seeds under the ordinary procedure. The biparentage assignments under the ordinary procedure corresponded to only 53.7% of the accurate separate assignments under the MH procedure. It is suggested that analyzing different seed tissues is effective for exact and accurate biparentage assignments in investigations of biparentally mediated gene flow in coniferous populations, particularly at the seed-dispersal stage.

Influence of Long-Distance Seed Dispersal on the Genetic Diversity of Seed Rain in Fragmented Pinus densiflora Populations Relative to Pollen-Mediated Gene Flow

“…The estimated genetic diversity of the trees, seeds, maternal alleles, and paternal alleles in 8 fragmented populations was similar to those in a natural P. densiflora population surrounded by many mature trees (Iwaizumi et al 2007) or a preserved P. densiflora population almost isolated from other mature trees (Lian et al 2001). Using microsatellite loci, H E value was estimated to be 0.898 (Iwaizumi et al 2007) and 0.915 (Lian et al 2001) in trees, ranged from 0.862 to 0.934 (Lian et al 2001) in seeds, and ranged from 0.785 to 0.937 (Iwaizumi et al 2010) in gametic alleles of the seeds.…”

“…Polymerase chain reaction (PCR) amplification was performed using the DNA Engine™ Model PTC-200 (MJ Research Inc., Hercules, CA) and a Multiplex PCR kit (Qiagen Inc., Valencia, CA). The PCR reaction was modified based on the standard SSR thermal reaction conditions recommended by the manufacturer (Iwaizumi et al 2007). The amplified fragment sizes were determined with an ABI PRISM 3100 genetic analyzer (Applied Biosystems Inc., Foster City, CA) against a GENESCAN-500 LIZ Size Standard (Applied Biosystems).…”

“…Using microsatellite loci, H E value was estimated to be 0.898 (Iwaizumi et al 2007) and 0.915 (Lian et al 2001) in trees, ranged from 0.862 to 0.934 (Lian et al 2001) in seeds, and ranged from 0.785 to 0.937 (Iwaizumi et al 2010) in gametic alleles of the seeds. The gametic-allele R values ranged from 6.87 to 19.08 (Iwaizumi et al 2010).…”

Effects of pollen supply and quality on seed formation and maturation in Pinus densiflora

“…If we assume that 'seed coat formation' equates with seed formation, our results indicate that seed formation occurs regardless of post-fertilization effects such as pollen quality. In addition, as DNA markers (SSRs) have confirmed that a seed coat is entirely maternally inherited diploid seed tissue in P. densiflora (Iwaizumi et al 2007), it is quite reasonable to assume that seed formation itself is not influenced by the paternally derived genetic effects via pollen gametes. Thus, pollination itself could be regarded as a 'trigger,' and hence the prerequisite condition, for seed formation.…”

Primer Note: Development of Highly Polymorphic Nuclear Microsatellite Markers for Hinoki (Chamaecyparis obtusa)

“…It has also been important to conserve the natural genetic resources and the within-population genetic diversity against potential depletion or contamination through overcutting or plantation practices. Highly polymorphic microsatellite (simple sequence repeat; SSR) markers have enhanced molecular studies of Japanese conifer species, in particular, genotypic discrimination of clones (e.g., HIRAO et al, 2006), gene flow in seed orchards and natural populations (e.g., MORIGUCHI et al, 2005;GOTO et al, 2005;IWAIZUMI et al, 2007;LIAN et al, 2008), and inter-population genetic structure (e.g., TAKAHASHI et al, 2005).…”