Hybridization Of Several Pines And Their Genetical Analysis

Interspecific hybrid test,hybrid identification by moleculer markers and estimation of heritability and combining ability were done with female parents Pinus elliottii Engelman var. elliottii×P. caribaea Morelet(PEE)and P. taeda L.(PTA) and male parents P. caribaea Morelet(PCA, including PCC(P. caribaea Morelet var. caribaea ), PCH( Pinus caribaea var. hondurensis Barrett et Golfari) and PCB (Pinus caribaea var. bahamensis Barrett et Golfari)) using general linear model(GLM) or mixed linear model of software SAS and ASReml and EST-SSR markers. Main results were as follows:(1)Genetic background of the female parents was analyzed with half-sib families of PEE and PTA using the evaluating parameters of genetic ability,combing ability,genetic gain and breeding value。The results showed that mean heritability of growth traits for half-sib families of PEE and PTA was 0.3-0.6, which was medium-low level;while the heritability for single trees ( h s2)was 0.1-0.3。Better selection effects was got by the stem height of PEE than PTA because of higher h s2 for PEE,and family selection was the better method for PTA。(2)Molecular markers reletated to GAs metabolism were developed from thousands of EST sequences in PGI data. 1170 gene-locus were amplified in 2 parents and their 39 F1 hybrids with 4 primer-pairs. The hybrids had 54.79% of the 1170 locus same as the male parent and 52.31% same as the female parent, and 24.79% was different from the parents, which showed the hybrid experiments made the new genetic genotype . 7 allele locus seleted from all 30 allele locus amplified by 4 primer pairs were related significantly to the traits of seedling height, and better seedlings in growth traits can be selected with higher positive rate using the 7 locus, which were the good molecular markers for early selection.(3) Genetic variation for the quality and size of cones and seeds of different hybrids and their parents were studied with T-test。The results showed that: length and width of single cone of Pinus taeda L.×P. caribaea Morelet(PTA×PC) were little smaller than the size of their female parents, while the quality of single cone(39.00g) of the hybrids was smaller significantly(P=0.05) than that(48.00g) of their female parents. The dispersion degree(Variance, standard deviation, range and CV ) of PEE×PCA and PTA×PCA were greater than their female parents,which showed the hybrids created more variation for selection.(4)Regression equation between the value(x) measured by Piloyn and wood basic density(y) measured by increment borer was constructed, which for PEE×PCA is y = -0.0127x + 0.5638 (P=0.0021,Coefficient of determination R2 = 0.3685);the equation for PTA×PCA is y = -0.0071x + 0.4668(P<0.0001,R2 = 0.4595)。(5)Heritability and combing ability for part of the growth and quality traits of PEE×PCA and PTA×PCA were estimated by testcross desingn(NCII ). The results showed that the effect on general combing ability(GCA)for the female parent of PEE×PCA was significant and the selection of female parent was important; h s2 of basic density and stem quality for female single trees was 0.2261-0.6382, and h s2 of growth traits for male single trees was 0.1289-0.3248. Genetic correlation and phenotypic correlation between growth traits and basic density of PEE×PCA was negative significantly, and the coefficient of genetic correlation was 1.14-1.16. The correlation between growth traits and stem quality was positive.The analysis of heritability(h2) of PTA×PCA showed that family mean heritability of growth,stem-straightness and wood density for female parents was higher than that for male parents, while the corresponding mean h2 for full-sib families was in the middle of the parents'heritability. The h2 of growth for female parents was 0.2923~0.4699, that for male parents was 0.1919~0.4033. The family mean and single tree h2 of wood basic density for female parents was 0.1764 and 0.0346, respectively, and the single tree h2 of stem-straightness for male and female parents was 0.1627 and 0.0983, respectively. The analysis of genetic correlation showed that the correlation between growth traits and stem-form was positive (|rG| =0.4672~0.3516), and that between growth traits and wood basic density was negative (|rG| =0.2203~0.6798). The ANOVA of combing ability showed that the GCA (general combining ability) effect of male or female parents for growth traits and stem-straightness has significant difference, and their effect of SCA(special combing ability) of combination for wood basic density was significant. The effective value of combing ability for GCA and SCA was estimated and the better parents and hybrids were evaluated. The correlation between genetic background of the parents and genetic differences of the progenies was discussed.(6)Early selection for growth traits for hybrid pines was studied. Genetic correlation coefficient of stem height of PEE×PCA between year 2001 and 2003 was 1.3839, that between year 2003 and 2005 was 2.0552, year 2005 and 2007 was 2.4196, which showed early selction for height was effective. Genetic correlation coefficient of volume of PTA×PCA among year 2003-2005 was 0.732 and 1.0081, and phenotypic correlation coefficient was 0.3927 and 0.8919 (P<0.01).Heritability and combing ability(or breeding value, BV)of PTA×PCA and PTA half-sib families were estimated fully using multi-sites and multi-years data by individual tree model of ASReml software. The results showed that h2 of tree height and diameter at floor height(DFH)for single tree were 0.1811±0.049 and 0.0939±0.0356,respectively.The value of SCA(Special combing ability) of height and DFH for 31-041×26 and 32-031×22 was relatively high. GCA of male parent PCH was totally higher than that of PCB and PCC。Better female parent PTAs were good provenances along the coast of USA such as 31161,31041 and 31062. Individual BV could be used for forward selection for establishing breeding population and parents with best BV plus higher SCA can be used for selection for deployment population (such as new seed orchards). Female parents of elite hybrids PTA×PCA were mainly common provenances(vs cold-resistant provenances), which were from Mississippi, South Carolina and North Carolina, on the selection of seven-year old hybrids planted in Hangzhou , Zhejiang(30°27′N,119°48′E).