Abstract
Some forest trees have been polyploidized to improve their traits and to supply new germplasms for breeding programs. As trees have a long juvenile stage, the early characterization of the chromosome set doubling effects is crucial for previous selection. Thus, we aimed to characterize the chemical variability of essential oils from diploid and autotetraploid germplasms (autotetraploid A and B) of Eucalyptus benthamii, as well as to evaluate their larvicidal and allelopathic effects. Autotetraploid A showed a higher essential oil yield than diploid and autotetraploid B, which did not differ quantitatively. Aromadendrene, viridiflorol and α-pinene were the major compounds in the diploid essential oil. In contrast, compounds were present in autotetraploids, such as 1,8-cineole, limonene, α-terpineol, and α-terpinyl-acetate. Essential oils from the diploid at 50–200 ppm were twice as larvicidal than those from autotetraploids against Aedes aegypti larvae. Considering the phytotoxicity bioassays using Lactuca sativa, essential oils from both ploidy levels affected root growth. Moreover, the essential oils inhibited shoot growth at all concentrations tested (187.5; 375; 750; 1500; and 3000 ppm). Autotetraploid A and B had the same effect on shoot growth as glyphosate. The essential oils had no cytogenotoxic effect on root meristematic cells of L. sativa, whereas phytotoxic potential was identified mainly in shoot growth. This work demonstrated a dramatic change in secondary metabolism (terpene composition) related to an increase in the ploidy level in Eucalyptus germplasms. In addition, we report the novelty of the chemical composition of essential oils among germplasms and their potential use as larvicidal and post-emergence weed control agents.
Highlights
Some forest trees have been polyploidized to improve their traits and to supply new germplasms for breeding programs
The yield and chemical composition of the essential oils (EOs) differed among the diploid and autotetraploid germplasms
The quantitative variation (%) among aromadendrene, viridiflorol, and 1,8-cineole had a positive correlation with yield (%) for each germplasm (0.62, 0.35, and 0.23, respectively) (Tables 2 and S2)
Summary
Some forest trees have been polyploidized to improve their traits and to supply new germplasms for breeding programs. We aimed to characterize the chemical variability of essential oils from diploid and autotetraploid germplasms (autotetraploid A and B) of Eucalyptus benthamii, as well as to evaluate their larvicidal and allelopathic effects. The essential oils had no cytogenotoxic effect on root meristematic cells of L. sativa, whereas phytotoxic potential was identified mainly in shoot growth. Breeders were able to select important phenotypic features to improve EO yield and tree adaptation to different environments in some species, such as Corymbia citriodora (Hook.) K.D. Hill & L.A.S. Johnson, Eucalyptus camaldulensis Dehnh., Eucalyptus radiata D. The gene copy increases alleles per locus, generating more overdominance than in diploid counterparts[16] The response for this effect covers the “omics” (genomic, epigenomic, transcriptomic, and metabolomic), resulting in different yield and composition of secondary metabolites, such as E O17. In spite of CSD could enhance EO production, a careful screening and selection still needed among the autopolyploid or allopolyploid germplasms, or both, based on chemical p rofiling[15,18,19]
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