Inheritance of growth and survival in two 9-year-old, open-pollinated progenies of an advanced breeding population of Chinese firs in southeastern China

Tree growth traits （tree height, DBH and stem volume） and survival from two 9-year-old, open-pollinated progeny tests of Chinese fir were investigated for heri- tability, genotype × environment interaction, age-age genetic correlation and selection efficiency. The 97 and 79 families planted at two sites were collected from the thirdcycle seed orchard. Individual heritability was estimated between 0.05 and 0.21 for tree height, DBH, and volume and between 0.45 and 1.0 for survival. Family heritability was between 0.20 and 1.14. Significant genotype x envi- ronment interaction was observed for the three growth traits. Type B genetic correlation was between 0.41 and 0.67 with an increasing trend as tree grows. High age-age genetic correlation was observed with correlation reaching 0.9 after age 4 for height, DBH, and volume. The genetic gains were estimated at 3.26, 3.39 and 5.98 % for tree height, DBH, and volume with 10 % selection intensity. The implication for advanced tree breeding in Chinese fir is discussed.

Transcriptome Analysis of Auxin Drives Cone Size Regulation in Fokienia hodginsii

As the reproductive organ of the endangered species Fokienia hodginsii,the size of the cones is a constraint on the reproductive renewal of the population.In this study,the molecular basis of the influence of cone size on F.hodginsii was elucidated by comparing the phenotype,biochemistry,and transcriptome of two cultivars of F.hodginsii(‘FJ431’and‘FJ415’).The two cultivars differed significantly in cone size,with FJ431 having a significantly larger cone size and weight than FJ415,1.32 and 1.90 times that of FJ415,respectively.RNA-Seq analysis of both cultivars retrieved 75,940 genes whose approximate functions were classified as the pathway of response to endogenous stimulus and response to hormone and showed significant differences in the auxin-activated signaling pathway,particularly the MAPK signaling pathway-plant.Furthermore,the endogenous IAA content was significantly higher in FJ431 than in FJ415,and 1.58 and 1.29 times more IAA was present in immature and mature cones,respectively.Moreover,exogenous IAA treatment significantly induced the expression of the MAPK pathway-related gene TRINITY_DN10564_c0_g1 and significantly inhibited the expression of the MAPK pathwayrelated gene TRINITY_DN17056_c0_g1.Our work suggests that IAA can affect the cone size of F.hodginsii,most probably through the MAPK pathway.This has high theoretical and practical significance for the improvement of genetic breeding and the further cultivation of quality germplasm resources of F.hodginsii.

Spatial analysis increases efficiency of progeny testing of Chinese fir

We used spatial, global trend and post-blocking analysis to examine the effectiveness of a progeny trial in a tree breeding program for Chinese fir （Cunninghamia lanceolata （Lamb.） Hook） on a hilly site with an environmental gradient from hill top to bottom. Diameter at breast height （DBH） and tree height data had significant spatial auto-correlations among rows and columns. Adding a firstorder separable autoregressive term more effectively modelled the spatial variation than did the incomplete block （IB） model used for the experimental design. The spatial model also accounted for effects of experimental design factors and greatly reduced residual variances. The spatial analysis rel- ative to the IB analysis improved estimation of genetic parameters with the residual variance reduced 13 and 19% for DBH and tree height, respectively; heritability increased 35 and 51% for DBH and tree height, respectively; and genetic gain improved 3-5%. Fitting global trend and postblocking did not improve the analyses under IB model. The use of a spatial model or combined with a design model is recommended for forest genetic trials, particularly with global trend and local spatial variation of hilly sites.