Aging seeds of weedy broomrapes and witchweeds lose sensitivity to strigolactones as DNA demethylates

Abstract

Broomrapes (Phelipanche and Orobanche spp.) and witchweeds (Striga and Alectra spp.) are obligate root parasitic weeds responsible for major crop yield losses worldwide. Their success in agricultural landscapes is attributable to their ability to produce thousands of long-lived minute seeds that coordinate their germination with the presence of nearby hosts by perceiving host-derived strigolactones. Nevertheless, the processes underlying the alleged decade(s)-long persistence in the field are understudied. Using an accelerated seed aging method coupled to germination and ELISA bioassays, we report that the loss of seed viability and germinability along seed aging is accompanied by a decrease in both strigolactone sensitivity and global DNA methylation. Our results also suggest that seeds of broomrapes are longer-lived than those of witchweeds. Overall, this study deems to initiate further research into how epigenetic mechanisms contribute to alterations in seed viability in parasitic weeds, and how seed aging influence seed responses to their environment.