Effects of Colchicine on Populus canescens Ectexine Structure and 2n Pollen Production.

Qing Zhou,Yaru Sang,Pingdong Zhang,Meiqin Liu,Jian Wu,Zhengyang Zhao

doi:10.3389/fpls.2020.00295

Abstract

Triploid breeding is a central way to improve growth traits, timber quality, and stress resistance in Populus. In the present study, the morphology and viability of colchicine-induced 2n pollen, triploid production by crossing induced 2n pollen, and identification of genetic constitution of colchicine-induced 2n pollen were conducted in Populus canescens based on optimizing technology for inducing chromosome doubling in pollen. We found that the meiotic stage, injection time, and the interaction between the meiotic stage and injection time had highly significant effects on the 2n pollen production rate. The most effective treatment for inducing 2n pollen was to give 11 injections of 0.5% colchicine solution when pollen mother cells (PMCs) were at the pachytene stage. The highest 2n pollen production rate was 30.27 ± 8.69%. Colchicine occasionally affected ectexine deposition, and some narrow furrows were detected in the ectexine structure. However, no significant difference was observed in the pollen germination rate between natural 2n pollen and colchicine-induced 2n pollen. Moreover, 5 triploids derived from FDR-type 2n pollen were generated by crossing induced 2n pollen, suggesting that colchicine does not eliminate the function of colchicine-induced 2n pollen. However, slower growth of 2n pollen tubes was responsible for a lower triploid production rate.

Highlights

IntroductionPopulus canescens (section Populus, family Salicaceae, genus Populus) grows in the Irtysh River Basin, Xinjiang Uygur Autonomous Region, in northwest China
Populus canescens grows in the Irtysh River Basin, Xinjiang Uygur Autonomous Region, in northwest China
We found that the dominant meiotic stage (F = 4.801, P = 0.009), injection time (F = 12.449, P = 0.000), and the interaction between the dominant meiotic stage and injection time (F = 3.006, P = 0.002) had highly significant effects on the frequency of colchicine-induced 2n pollen according to the univariate general linear model (GLM) analysis

Summary

Introduction

Populus canescens (section Populus, family Salicaceae, genus Populus) grows in the Irtysh River Basin, Xinjiang Uygur Autonomous Region, in northwest China. The annual growth rate of P. canescens is lower owing to its shorter growing season. A long-term breeding program was developed by Beijing Forestry University to improve P. canescens growth. In 1989, a cross-breed between Populus tomentosa × Populus bolleana and P. canescens was first reported by Li and Zhu (1989), and six superior hybrid clones were developed. In a subsequent study, Duan and Yang (1998) evaluated the cold and drought resistance of these superior hybrids by the anatomical structure of the leaves, water loss rate through the Artificial Polyploidy in Hairy Poplar leaves, and electroconductivity of the shoots. Tian J. et al, 2018 systematically studied the abnormal behavior of chromosomes during meiosis of pollen mother cells (PMCs), pollen morphology and pollen abortion in some male hybrids between P. tomentosa × P. bolleana and P. canescens In a subsequent study, Duan and Yang (1998) evaluated the cold and drought resistance of these superior hybrids by the anatomical structure of the leaves, water loss rate through the Artificial Polyploidy in Hairy Poplar leaves, and electroconductivity of the shoots. Tian J. et al, 2018 systematically studied the abnormal behavior of chromosomes during meiosis of pollen mother cells (PMCs), pollen morphology and pollen abortion in some male hybrids between P. tomentosa × P. bolleana and P. canescens

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