Two awn-development-related peptides, GAD1 and OsEPFL2, promote seed dispersal and germination in rice

In nature, seed dispersal and germination are crucial for plant survival and propagation. Elaborate mechanisms have evolved that enhance the success of these events ( Peart, 1981 Peart M.H. Further experiments on the biological significance of the seed-dispersal units in grasses. J. Ecol. 1981; 69: 425-436https://doi.org/10.2307/2259677 Crossref Google Scholar ; Bewley, 1997 Bewley J.D. Seed germination and dormancy. Plant Cell. 1997; 9: 1055-1066https://doi.org/10.1105/tpc.9.7.1055 Crossref PubMed Scopus (2236) Google Scholar ), and the widespread distribution of grass species has been associated with the evolution of these traits. Many of these mechanisms are associated with characteristics that are intrinsic to the seed, such as awn development, seed shattering, and germination ( Ntakirutimana et al., 2019 Ntakirutimana F. Xiao B. Xie W. Zhang J. Zhang Z. Wang N. Yan J. Potential effects of awn length variation on seed yield and components, seed dispersal and germination performance in Siberian Wildrye. Plants. 2019; 8: 561https://doi.org/10.3390/plants8120561 Crossref Scopus (16) Google Scholar ). Awns and/or other seed appendages often help mature seeds to disperse widely and germinate under various challenging environments ( Elbaum et al., 2007 Elbaum R. Zaltzman L. Burgert I. Fratzl P. The role of wheat awns in the seed dispersal unit. Science. 2007; 316: 884-886https://doi.org/10.1126/science.1140097 Crossref PubMed Scopus (474) Google Scholar ). For example, the awns of wheat react to a change in humidity and propel the seeds into moist soil to facilitate seed germination ( Elbaum et al., 2007 Elbaum R. Zaltzman L. Burgert I. Fratzl P. The role of wheat awns in the seed dispersal unit. Science. 2007; 316: 884-886https://doi.org/10.1126/science.1140097 Crossref PubMed Scopus (474) Google Scholar ). It has also been shown that awn length has a remarkable correlation with seed germination in some grass species ( Ntakirutimana et al., 2019 Ntakirutimana F. Xiao B. Xie W. Zhang J. Zhang Z. Wang N. Yan J. Potential effects of awn length variation on seed yield and components, seed dispersal and germination performance in Siberian Wildrye. Plants. 2019; 8: 561https://doi.org/10.3390/plants8120561 Crossref Scopus (16) Google Scholar ; Liu et al., 2018 Liu W. Wang T. Zhang S. Ding L. Wei Z. Grazing influences Stipa breviflora seed germination in desert grasslands of the Inner Mongolia Plateau. PeerJ. 2018; 6: e4447https://doi.org/10.7717/peerj.4447 Crossref PubMed Scopus (10) Google Scholar ). However, it is not known whether the pathways that promote awn development and regulate seed germination rate are linked or whether rice awns contribute to successful seed germination in nature.