Selective Inhibition of Wild Sunflower Reproduction with Mugwort Aqueous Extract, Tested on Cytosolic Ca2+ and Germination of the Pollen Grains

Alberto Marco Del Pino; Euro Pannacci; Alessandro Di Michele; Elisabetta Bravi; Ombretta Marconi; Francesco Tei; Carlo Alberto Palmerini

doi:10.3390/plants10071364

Selective Inhibition of Wild Sunflower Reproduction with Mugwort Aqueous Extract, Tested on Cytosolic Ca²⁺ and Germination of the Pollen Grains

Plants (Basel). 2021 Jul 3;10(7):1364. doi: 10.3390/plants10071364.

Authors

Alberto Marco Del Pino¹, Euro Pannacci¹, Alessandro Di Michele², Elisabetta Bravi¹, Ombretta Marconi¹, Francesco Tei¹, Carlo Alberto Palmerini¹

Affiliations

¹ Department of Agricultural, Food and Environmental Sciences, University of Perugia, Via Borgo XX Giugno 74, 06121 Perugia, Italy.
² Department of Physics and Geology, University of Perugia, Via Pascoli, snc, 06123 Perugia, Italy.

Abstract

Wild sunflower (Helianthus annuus L.) is an invasive species widely distributed in several regions of the world, where it shares a large area with domesticated sunflower. The imidazolinone-tolerant sunflower enables the control of problematic weeds (such as Xanthium spp., Brassica spp., wild sunflower) with imidazolinone herbicides (Clearfield^® production system) in cultivated sunflower crops, but could facilitate the gene transfer of herbicide resistance, from cultivated sunflower to wild sunflower, generating hard-to-control weed biotypes or herbicide-resistant populations. The development of new practices that involve the selective inhibition of reproduction structures, such as pollen granules, could be an innovative strategy to minimize outcrossing and the origin of weed-crop hybrids in Clearfield^® production systems. In this study, the effects of mugwort (Artemisia vulgaris L.) aqueous extract on cytosolic Ca²⁺ and the germination of pollen grains collected from conventional, wild and IMI-tolerant sunflower were tested. The results showed that mugwort deregulated Ca²⁺ homeostasis and markedly reduced the germination of conventional and wild sunflower pollen, but not IMI-tolerant pollen. The HPLC analysis revealed the presence of phenolic acids belonging to the hydroxycinnamic and benzoic classes in the mugwort extract. Hydroxycinnamic acids (caffeic and ferulic) deregulated the cytosolic Ca²⁺ of conventional and wild sunflower pollen, but not those which were IMI-tolerant, similar to mugwort extract. Selective inhibition of wild sunflower pollen in the Clearfield^® sunflower crop contributes to a possible new weed management strategy, reducing the wild sunflower reproduction by seed, minimizing the potential risks of outcrossing with the formation of weed-crop hybrids. The Ca²⁺ selective chelating activity of caffeic or ferulic acids provides elements to be investigated for their possible use as an alternative to mugwort extract.

Keywords: IMI technology; caffeic acid; ferulic acid; imidazolinone-tolerant crops; new weed management strategy; outcrossing; pollen germination; wild sunflower.