Induction of tetraploid hardy rubber tree, <i>Eucommia ulmoides</i>, and phenotypic differences from diploid

Abstract

Polyploid plants tend to have larger organs than diploids due to the doubling of their chromosome number. However, the enlarged regions, whether cells, tissues, or individuals differ depending on the plant species or taxon, as have metabolic changes. Eucommia ulmoides is a deciduous dioecious plant natively distributed in China that accumulates trans-1,4-polyisoprene (TPI) in laticifers throughout its tissues. To induce tetraploids of E. ulmoides, colchicine treatment time and concentration were assessed for ability to obtain tetraploids, and the resulting plants were analyzed for phenotypic differences from diploids with respect to individual size, 16 leaf attributes, sizes of three cell types (epidermis, laticifer, and parenchyma), and TPI content and molecular weight. Effective conditions for obtaining tetraploids were 0.05% colchicine for 48 h, which led to obtaining a total of 9 tetraploids. The tetraploids showed larger stomata size but lower stomata density than diploids. Significant differences in the mean values of other attributes including leaf size, cell size, and TPI content of tetraploids could not be detected between tetraploids and diploids, suggesting that E. ulmoides is less affected by gene doubling than other plant species, and that tetraploid individuals might not have a tendency to increase their biomass.

Comparative Transcriptomic, Anatomical and Phytohormone Analyses Provide New Insights Into Hormone-Mediated Tetraploid Dwarfing in Hybrid Sweetgum (Liquidambar styraciflua × L. formosana)

“…After chromosome doubling, polyploid plants often exhibit multiple variations and generally develop large organs, strong resistance, high crop yield, wood quality, and ornamental value ( Zhu et al, 1995 ; Leitch and Leitch, 2008 ; Tiku et al, 2014 ). However, after polyploidization, the changes in plant height differ among species; there is usually a fast growing type ( Ni et al, 2009 ; Miller et al, 2012 ; Dai et al, 2015 ; Liao et al, 2016 ) and a dwarf type ( Mu et al, 2012 ; Tokumoto et al, 2016 ; Xue et al, 2017 ). Similar to fast growth, dwarfing is a common phenomenon in tetraploid plants, especially woody plants.…”

Polyploidy in Industrial Crops: Applications and Perspectives in Plant Breeding

“…Another species producing an important metabolite, trans-1,4-polyisoprene (TPI), used as an industrial raw material, is E. ulmoides. Studies of the effect of polyploidisation on TPI content in this species showed no significant differences between tetraploids and diploids [67].…”

“…Equally high genome doubling efficiency was obtained for Nicotiana alata J. Link and C. Otto and Eucommia ulmoides Oliver by soaking the seeds in a 0.5% colchicine solution for 48 h [66,67]. Dhamayanthi and Gotmare [68] treated seeds as well as seedlings and stem cuttings with colchicine to induce tetraploids of Gossypium armourianum Kearney and G. aridum Rose and Standley and found that seeds are the most suitable plant material in inducing polyploidy.…”

“…For example, tetraploids E. ulmoides have a lower tendency to increase cell size, thereby increasing its biomass compared to other species. This is probably related to the silencing of certain duplicated genes [67]. An equally interesting example is octoploid J. curcas, whose leaves are much smaller than those of diploids, while the leaf cells of octoploids are larger [5].…”

High-Depth Transcriptome Reveals Differences in Natural Haploid Ginkgo biloba L. Due to the Effect of Reduced Gene Dosage

“…Larger cells and more cellular content can accumulate more energy for their growth and development. Qualitative differences in morphology, growth, and physiology and biochemistry among ginkgos of different ploidy follow the laws of ploidy, as has been demonstrated on Liriodendron sino-americanum [ 36 ], Eucommia [ 37 ], rice [ 38 ], Rhododendron fortunei [ 39 ], and Thymus vulgaris [ 40 ]. However, this is not absolute; for example, the size of pure tetraploid apples ( Malus × domestica ) and Citrus limonia are smaller compared to their diploid counterparts [ 41 , 42 ].…”