Molecular classification of hybrid larch seedling and origin of larch in Hokkaido Island

落叶松属树种间的各种杂交种由于具有杂种优势而被广泛应用于世界各地的商品林业。在日本，由日本落叶松和日本落叶松杂交而成的千岛落叶松是北海道岛最重要的造林树种之一。这种杂交落叶松结合了两个亲本物种的理想特征，包括快速的幼龄生长、茎直和相对较强的抗红腹鼠啃噬能力。因此，区分光叶百合杂种苗与光叶百合（GG）杂种苗具有重要意义。我们确定了诊断叶绿体DNA和线粒体DNA标记，可以（i）区分L.gmelinii var.japonica和L.kaempferi，和（ii）确定它们之间的杂种的母本和父本物种，通过利用两个基因组之间的遗传模式的差异。我们还调查了在一个地点与两种类型的杂交率 关于我们 种间种子果园一个新的类型与行中的一个单一的母系克隆的L.gmelinii变种日本L.kaemferi行，和一个“传统”的类型与多个，密切混合的克隆-在两年内使用叶绿体诊断DNA标记。SMC种间种子园的平均杂交率高于传统种间种子园，这是由于落叶松的自交不亲和性造成的。日本无性系两个调查年度果园类型间杂交率差异极显著（P<0.001）。这一发现表明，SMC种间种子园可以可靠地提供种子与高比例的杂交种。判别分析表明，2年生根颈直径、二次枝数和地上2年生顶芽着生天数对单株杂种分类能力较强。这些特点将为改进常规方法提供参考。该种自然居群遗传结构较弱，但Mt.通过SSR和线粒体DNA分析，马诺卡米群体具有独特的遗传多样性。通过DNA分析，认为北海道岛的优树种群起源于日本中部地区，如长野县川上村。少

Various hybrids between Larix species have been used in commercial forestry around the world because they have heterotic advantages. In Japan, a hybrid between Kurile larch (Larix gmelinii var.japonica) and Japanese larch (L.kaempferi) is one of the most important afforestation species in Hokkaido Island. This hybrid larch combines desirable traits of both parental species, including fast juvenile growth, stem straightness and relatively strong resistance to gnawing by Myodes rufocanus bedfordiae. Therefore, it is important to distinguish the hybrid seedlings from pure L.gmelinii var.japonica × L.gmelinii (GG) seedlings. We identified diagnostic chloroplast DNA and mitochondrial DNA markers that can (i) discriminate between L.gmelinii var.japonica and L.kaempferi, and (ii) determine the maternal and paternal species of hybrids between them, by exploiting the difference in inheritance mode between the two genomes. We also investigated the hybridization rates at a site with two types of … More inter-specific seed orchard.-a new type with rows of a single maternal clone of L.gmelinii var japonica amongst rows of L.kaemferi, and a "traditional" type with multiple, intimately mixed clones-in two years using chloroplast diagnostic DNA markers. The average hybridization rates in the SMC inter-specific seed orchards were higher than that in the traditional inter-specific seed orchards, because of the self-incompatibility of the L.gmelinii var. japonica clone. We detected significant differences in hybridization rates between the orchard types in both investigated years (P<0.001, ANOVA). This finding suggests that SMC inter-specific seed orchards can reliably provide seeds with high proportions of hybrids. The discriminant analysis revealed that root collar diameter and number of sylleptic branches at 2-years-old, and day of terminal bud set at land 2-yaers-old have high ability for hybrid classification of individual seedlings. These traits will be worked for improving the common method. The genetic structure of natural population of this species was weak but Mt. Manokami population has unique genetic diversity by both of SSRs and mitocondorial DNA analyses. The origin of plus tree population in Hokkaido Island was thought to be central Japan such as Kawakami village of Nagano prefecture by DNA analysis. Less