The role of wild rice (Oryza rufipogon) awns in seed dispersal

Abstract

Cultivated rice (Oryza sativa L.) was domesticated from the Asian wild species O. rufipogon. Compared with cultivated rice, wild rice has spikelets/seeds with long barbed awns. In order to evaluate the role of awns in wild rice, four seed groups with different awn lengths (full, half, quarter and no awns) were prepared, and the following seed dispersal movements were investigated under simulated natural conditions as observed in the tropical Asian habitat: (1) seed detachment from the parent plant; (2) falling angle of mature seed; (3) ability to slip into small spaces; (4) horizontal movement on the ground and (5) horizontal movement in water. As a result, awns were found to enhance the detachment of matured seeds from the panicles in the initial seed dispersal step. They regulated vertical orientation in the air, and the vertical form may enable seeds to squeeze to the ground. The awned seeds also showed advantages in horizontal movements on the ground and in the water. In most of the experiments, seeds with full awns showed the best performance for seed dispersal, suggesting that wild rice keeps long awns to survive under natural conditions. Since seed awning is dominantly controlled by wild functional alleles at several loci, wild rice may be able to prevent a drastic reduction of awn length.

Wild and cultivated allele effects on rice phenotypic traits in reciprocal backcross populations between <i>Oryza rufipogon</i> and two cultivars, <i>O. sativa</i> Nipponbare and IR36

“…It produces awned spikelets on the spreading panicles and disperses the mature seeds (Fig. 1) (Amarasinghe et al 2020b). Its pericarp and hull colors are red and black, respectively, while the two cultivars have straw-colored seeds with white pericarp (Fig.…”

Inflated Ovary May Increase the Dispersal Ability of Three Species in the Cold Deserts of Central Asia

“…Angiosperms have evolved a diversity of morphological structures, including hairs [ 20 ], wings [ 14 , 21 ], awns [ 22 ], spines [ 23 , 24 ], bracts [ 25 , 26 ], elaiosomes [ 27 , 28 ], mucilage [ 29 , 30 ], and inflated calyx [ 31 ], which improve the diaspore dispersal capacity via different vectors [ 32 ]. Calyx inflation occurs during fruit maturation and results in a hollow, gas-filled structure [ 33 , 34 ], which has primarily been observed in taxa such as Anisodus , Nicandra , Physaliastrum , Physalis , Physochlaina , Przewalskia , and Withania in the Solanaceae, Coleus in the Labiatae, and Astragalus in the Fabaceae [ 33 , 35 , 36 ].…”