Triploid production via heat-induced diploidisation of megaspores in Populus pseudo-simonii
- 55 Downloads
Triploid breeding in Populus enhances the commercial properties of cultivated trees. Sexual polyploidization through the production of diploid gametes produces elite triploids with heterosis and ploidy vigour. Populus pseudo-simonii is a species indigenous to China. It is highly adaptable and resistant drought, cold, and saline–alkaline stresses. To improve the properties in growth and pulpwood traits of P. pseudo-simonii, we used heat treatments to induce chromosome doubling in the megaspores as a first step in the production of triploid saplings. The heat treatments were applied during development stages of the female flower buds. We produced 117 triploids via the diploidisation of megaspores. The highest proportion of triploids among the offspring (51.43%) was obtained by applying a heat treatment of 40 °C over 4 h to flower buds in which one-third of the catkins were outside the bract scales. The proportion of pachytene was positively correlated with the average rate of triploid production in each bud developmental stage. Thus, among the phases of meiosis, the pachytene stage may be most susceptible to heat treatments aiming to diploidise the megaspores in P. pseudo-simonii. The megasporocytes in these treated flower buds were mostly in the first meiotic division stages, suggesting that the first meiotic division restitution (FDR) type 2n megaspores may have been induced by our experimental procedures. These triploid hybrids derived from FDR type 2n megaspores will probably contribute significantly to programmes aimed at improving commercial properties of Populus congeners in the section Tacamahaca.
KeywordsPopulus pseudo-simonii Triploid breeding Unreduced megaspore High temperature First meiotic division restitution (FDR)
We thank the Forestry Research Institute of Tongliao City, the Inner Mongolia Autonomous Region, P. R. China, for collecting the plant material and for additional help. This work was supported by the Fundamental Research Funds for the Central Universities (2018ZY30), the National Natural Science Foundation of China (31470662) and the program from the Beijing Municipal Education Commission (CEFF-PXM2018_014207_000024).
JW conceived and designed research. DL, JT and YX conducted experiments. HC analysed the data. DL and JW wrote and revised the manuscript. All authors read and approved the manuscript.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no competing interests.
- Brukhin V, Hernould M, Gonzalez N, Chevalier C, Mouras A (2003) Flower development schedule in tomato Lycopersicon esculentum cv. sweet cherry. Sex Plant Reprod 15:311–320Google Scholar
- Einspahr DW (1984) Production and utilization of triploid hybrid aspen. Iowa State J Res 58:401–409Google Scholar
- Hermsen JGT (1984) Mechanisms and genetic implications of 2n-gamete formation. Iowa State J Res 58(4):421–434Google Scholar
- Johnsson H, Eklundh C (1940) Colchicine treatment as a method in breeding hardwood species. Svensk Papp Tidn 43:373–377Google Scholar
- Kang XY (2010) Some understandings on polyploid breeding of poplars. J Beijing For Univ 32(5):149–153Google Scholar
- Kang XY (2016) Polyploid induction techniques and breeding strategies in poplar. In: Mason AS (ed) Polyploidy and hybridization for crop improvement. CRC Press, Boca Raton, pp 76–96Google Scholar
- Kang XY, Zhu ZT (1997) A study on the 2n pollen vitality and germinant characteristics of white poplars. Acta Botanica Yunnanica 19:402–406Google Scholar
- Kang XY, Zhu ZT, Lin HB (1999) Study on the effective treating period for pollen chromosome doubling of Populus tomentosa × P. bolleana. Sci Silvae Sin 35(4):21–24Google Scholar
- Kang XY, Zhu ZT, Zhang ZY (2000) Breeding of triploids by the reciprocal crossing of Populus alba × P. glandulosa and P. tomentosa × P. bolleana. J Beijing For Univ 22:8–11Google Scholar
- Li SW, Zhang ZY, He CZ, An XM (2004) Progress on hybridization breeding of poplar in China. World For Res 17(2):37–41Google Scholar
- Mashkina OS, Burdaeva LM, Belozerova MM, Vyunova LN (1989) Method of obtaining diploid pollen of woody species. Lesovedenie 1:19–25Google Scholar
- Nilsson-Ehle H (1936) Note regarding the gigas form of Populus tremula found in nature. Hereditas 21:372–382Google Scholar
- Seitz FW (1954) The occurrence of triploids after self-pollination of anomalous androgynous flowers of a grey poplar. Z Forstgenet 3:1–6Google Scholar
- Wang J, Kang X (2008) Megasporogenesis and female gametophyte development of Populus pseudo-simonii Kitag. and its phylogenetic implications. In: Proceedings of forest genetics and tree breeding in the age of functional genomics. The second forestry academic conference of China, Nanning, pp 614–620Google Scholar
- Yao CL, Pu JW (1998) Timber characteristics and pulp properties of the triploid of Populus tomentosa. J Beijing For Univ 20:18–21Google Scholar
- Zhu ZT, Lin HB, Kang XY (1995) Studies on allotriploid breeding of Populus tomentosa B301 clones. Sci Silvae Sin 31:499–505Google Scholar