Inbreeding in Chinese fir: Insight into the rare self-fertilizing event from mRNA, miRNA and copy number variation view

Self-fertilization (selfing, autogamy) is an extreme form of inbreeding that exhibits more severe inbreeding depression characterized by reduced seed yield and vigor, stunted growth and development, poor stress resistance, and even mortality. Selfing also offers an opportunity for reproductive success even in the absence of available mates or pollinators and may give their offspring the ability to adapt to variations in climate, geography, and reproductive systems.Thus, selfing can produce differential mutant progeny, thereby increasing the opportunity for phenotypic selection among families. In generally, Chinese fir (Cunninghamia lanceolata) was regared as an outcrossing woody plant, and its selfed progenies usually show high level of inbreeding depression with reduced growth.In our previous study, we identified a clone parent, cx569, that produced selfed progeny with lower levels of inbreeding depression in the seedling stage and emerged as two distinct populations with high vigor (Including medium to upper level growth vigor) and low vigor. The aim of this study was to investigate the molecular basis of selfed seedlings with high vigor and identify the enriched processes and pathways in differentially expressed genes. Moreover, we further explore the mechanism of high vigor in selfed seedlings from a copy number variation perspective. These results provide a view of advanced phenomena under selfing and offer a new choice for tree improvement in mating.