How gathering wild rice under human-mediated drought stress could have inadvertently paved the way to Asian rice incipient domestication and cultivation

Abstract

In eastern China, on the southern end of the Yangtze Valley, early Holocene hunter-gatherers were foraging various plants, including wild rice – Oryza rufipogon Griff. – an aquatic and perennial plant which is the wild progenitor of domesticated rice. According to optimal foraging theory, these foragers should have tried to enhance the efficiency of harvesting wild rice seeds by draining water around the plants before seeds ripened and shattered. This proto-cultivation practice led to unintended consequences given that wild rice responds to drought stress owing to its phenotypic plasticity. Plant and panicle architectures were modified with transitions to more compact and erect tillers and to a closed panicle shape. They provide incentives to early foragers for intensifying their proto-cultivation practices and so could have also triggered initial cultivation of rice. They also triggered incipient domestication of rice, starting by the transition to selfing. According to this narrative, it is even possible that rice incipient domestication preceded cultivation.

Northern Wild Rice (Zizania palustris L.) breeding, genetics, and conservation

“…There is evidence that drought tolerance played a role in the domestication of wheat (Gui et al., 2021; Lv et al., 2019) and white rice (Svizzero, 2022; Zheng et al., 2014) as well. In white rice, for example, Svizzero (2022) suggests that early foragers inadvertently played a significant role in the specie's earliest domestication events as they tried to improve harvesting efficiency by draining water around wild plants, which were able to respond due to their phenotypic plasticity. Looking into the selection events that have taken place in cultivated NWR over the last 60 years (Haas et al., 2022) provides an example of how we are now able to capture the ongoing changes in a domesticated crop compared with its wild counterparts.…”

“…This management practice requires that NWR plants continue to grow and set seed on dry land and was likely a large bottleneck during the very beginning of the species domestication process. There is evidence that drought tolerance played a role in the domestication of wheat (Gui et al., 2021; Lv et al., 2019) and white rice (Svizzero, 2022; Zheng et al., 2014) as well. In white rice, for example, Svizzero (2022) suggests that early foragers inadvertently played a significant role in the specie's earliest domestication events as they tried to improve harvesting efficiency by draining water around wild plants, which were able to respond due to their phenotypic plasticity.…”