title: Needle morphological evidence of the homoploid hybrid origin of Pinus densata based on analysis of artificial hybrids and the putative parents, Pinus tabuliformis and Pinus yunnanensis.
abstract: Genetic analyses indicate that Pinus densata is a natural homoploid hybrid originating from Pinus tabuliformis and Pinus yunnanensis. Needle morphological and anatomical features show relative species stability and can be used to identify coniferous species. Comparative analyses of these needle characteristics and phenotypic differences between the artificial hybrids, P. densata, and parental species can be used to determine the genetic and phenotypic evolutionary consequences of natural hybridization. Twelve artificial hybrid families, the two parental species, and P. densata were seeded in a high-altitude habitat in Linzhi, Tibet. The needles of artificial hybrids and the three pine species were collected, and 24 needle morphological and anatomical traits were analyzed. Based on these results, variations in 10 needle traits among artificial hybrid families and 22 traits among species and artificial hybrids were predicted and found to be under moderate genetic control. Nineteen needle traits in artificial hybrids were similar to those in P. densata and between the two parental species, P. tabuliformis and P. yunnanensis. The ratio of plants with three needle clusters in artificial hybrids was 22.92%, which was very similar to P. densata. The eight needle traits (needle length, the mean number of stomata in sections 2 mm in length of the convex and flat sides of the needle, mean stomatal density, mesophyll/vascular bundle area ratio, mesophyll/resin canal area ratio, mesophyll/(resin canals and vascular bundles) area ratio, vascular bundle/resin canal area ratio) relative to physiological adaptability were similar to the artificial hybrids and P. densata. The similar needle features between the artificial hybrids and P. densata could be used to verify the homoploid hybrid origin of P. densata and helps to better understand of the hybridization roles in adaptation and speciation in plants.
authors: National Engineering Laboratory for Forest Tree Breeding, Key Laboratory for Genetics and Breeding of Forest Trees and Ornamental Plants of Ministry of Education, Beijing Forestry University Beijing, 100083, China.
authors: Fangqian
authors: F
authors: Xing
authors: National Engineering Laboratory for Forest Tree Breeding, Key Laboratory for Genetics and Breeding of Forest Trees and Ornamental Plants of Ministry of Education, Beijing Forestry University Beijing, 100083, China.
authors: Jian-Feng
authors: JF
authors: Mao
authors: National Engineering Laboratory for Forest Tree Breeding, Key Laboratory for Genetics and Breeding of Forest Trees and Ornamental Plants of Ministry of Education, Beijing Forestry University Beijing, 100083, China.
authors: Jingxiang
authors: J
authors: Meng
authors: National Engineering Laboratory for Forest Tree Breeding, Key Laboratory for Genetics and Breeding of Forest Trees and Ornamental Plants of Ministry of Education, Beijing Forestry University Beijing, 100083, China.
authors: Jianfeng
authors: J
authors: Dai
authors: State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences Beijing, 100093, China.
authors: Wei
authors: W
authors: Zhao
authors: College of Resources and Environment, College of agriculture and animal husbandry of Tibet University Linzhi, 860000, China.
authors: Hao
authors: H
authors: Liu
authors: College of Resources and Environment, College of agriculture and animal husbandry of Tibet University Linzhi, 860000, China.
authors: Zhen
authors: Z
authors: Xing
authors: College of Resources and Environment, College of agriculture and animal husbandry of Tibet University Linzhi, 860000, China.
authors: Hua
authors: H
authors: Zhang
authors: National Engineering Laboratory for Forest Tree Breeding, Key Laboratory for Genetics and Breeding of Forest Trees and Ornamental Plants of Ministry of Education, Beijing Forestry University Beijing, 100083, China ; Department of Ecology and Environmental Science, Umeå University SE-901 87, Umeå, Sweden.
authors: Xiao-Ru
authors: XR
authors: Wang
authors: National Engineering Laboratory for Forest Tree Breeding, Key Laboratory for Genetics and Breeding of Forest Trees and Ornamental Plants of Ministry of Education, Beijing Forestry University Beijing, 100083, China.
authors: Yue
authors: Y
authors: Li
keywords: Anatomy; Pinus densata; Pinus tabuliformis; Pinus yunnanensis; artificial hybrid; morphology