Mating patterns and pollen dispersal in a Japanese larch clonal seed orchard:a case study

作   者：xingbin chen, xiaomei sun, leiming dong, shougong, zhang
期刊名称：Science China Life Sciences
影响因子：3.085
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页     码：
关键词：Larix kaempferi, simple sequence repeats (SSRs), paternity analysis, pollen contamination, pollen dispersal, growth performance
论文摘要：
Pollination dynamics highly determines the genetic quality of seed orchard crops. However, there is less research about the effect
of mating patterns on seed productivity of orchard crops. So far, clonal seed orchards have been producing genetically improved
seedlings used for most Japanese larch (Larix kaempferi (Lamb.) Carr.) plantations in China. In the present study, a total of 17
highly variable simple sequence repeat (SSR) markers were used for genotyping a progeny trial population consisting of 647
open-pollinated progenies germinated from seeds which were collected from 63 maternal clones with 140 potential paternal
clones in a Japanese larch clonal seed orchard in China. Paternity analysis was used in the present case study in order to evaluate
the level of paternal gametic contribution, estimate pollen contamination and selfing rates, and investigate pollination patterns,
pollen dispersal patterns and the impact of mating patterns on seed productivity of orchard crops. We observed 93.7% of the
success rate of the parental assignment, unequal paternal gametic contribution (0–12.4%) with 6.3% of the progenies derived
from pollen contamination or unsampled pollen donors, and absence of evidence for selfing. We also found that pollination rate
highly depended on the distance between pollen donors and maternal parents, the majority of the identified crossing (65.7%)
occurred between clones within a 150-m radius, and large variations in growth performance existed among the paternal halfsiblings.
Progeny growth performance (diameter at breast (DBH) and height (HGT)) was measured at Age-20 in order to
investigate the impact of mating patterns on timber production of orchard crops. As either the paternal or maternal, two clones (i.
e., clones Z38 and Z62) were identified to have produced progenies with higher average stem volume breeding values than that of
all of the progenies. Specifically, the genetic gains for volume were 3.53% for the two clones as paternal parents, and 8.26% as
the maternal parents at Age-20. Thus, both elite clones were ideal candidates for the construction of next-generation clonal seed
orchards due to their synchronous reproductive phenology with greater crossing rate and higher genetic gain. These results
improved the pedigree information to provide solid evidence of mating patterns for future design and effective management of
seed orchards and for the development of viable long-term breeding strategies for other coniferous species.