Abstract
Polyploid plants often have higher biomass and superior crop qualities. Breeders therefore search for crop germplasm with higher ploidy levels; however, whether higher ploidy levels are associated with better performance remains unclear. Actinidia arguta and related species, whose commercialized fruit are referred to as kiwiberries, harbor a series of ploidy races in nature, offering an opportunity to determine the link between ploidy levels and agronomic traits. In the present study, we determined the ploidy levels of A. arguta var. arguta, A. arguta var. giraldii, and A. melanandra in 16 natural populations using flow cytometry, and examined 31 trait variations in fruits, leaves and flowers by field observations, microscopic examination and laboratory analyses. Our results showed that octaploid and decaploid A. arguta var. giraldii had larger dimension of leaves than tetraploid A. arguta var. arguta and A. melanandra, but their fruits were significantly smaller. In addition, A. arguta var. giraldii (8x and 10x) had higher contents of nutrients such as ascorbic acid and amino acids; however, some important agronomic traits, including the content of total sugar and total acid, were significantly lower in the octaploids and decaploids. Moreover, octaploids and decaploids did not result in greater ecological adaptability for the challenging environments and climates. In conclusion, the differentiation of ecological adaptability and traits among natural kiwiberries' cytotypes suggested that higher ploidy levels are not inevitably advantageous in plants. The findings of A. arguta and related taxa in geographical distribution and agronomic trait variations will facilitate their germplasm domestication.
Highlights
Polyploidy, or whole genome duplication, has been an important feature of evolution and diversification in flowering plants (Otto and Whitton, 2000)
Octoploids and decaploids were initially discovered in natural A. arguta var. giraldii var. giraldii, which scattered in Qinling Mountains
We cautiously concluded that natural kiwiberries (A. arguta var. giraldii and related species) has the ploidy levels as following: A. hypoleuca -2x, A. melanandra - 4x, A. arguta var. giraldii var. arguta -4x, 6x, 7x, and 8x, A. arguta var. giraldii var. giraldii −8x and 10x
Summary
Polyploidy, or whole genome duplication, has been an important feature of evolution and diversification in flowering plants (Otto and Whitton, 2000). The genomic changes subsequently altered plant physiology, morphology, phenology, and/or ecology within only one or a few generations (Levin, 2002), in particular, improved agronomical traits in some polyploid crops (Dubcovsky and Dvorak, 2007; Leitch and Leitch, 2008). Other changes in crop quality, such as doubling the amount of soluble proteins in Panicum virgatum (Warner et al, 1987), increased amino acid content in sorghum (Luo et al, 1992), improved fruit quality in tomato (Kagan-Zur et al, 1991) and higher secondary metabolite levels in Cymbopogon (Lavania et al, 2012), have been observed. The elevated ploidy level does not consistently increase body size (Lavania, 2013). We want to ask more: do organisms with higher ploidy levels or multipolyploidization (e.g., octoploid or decaploid) really perform better than their ancestors; namely, “the more (chromosome), the better?”
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
