Evaluation of a Recessive Male Floret Color in Cultivated Northern Wild Rice (Zizania palustrisL.) for Pollen-Mediated Gene Flow Studies

Abstract

Northern wild rice (NWR; Zizania palustris L.) is a wind-pollinated, annual, aquatic grass that grows naturally in the Great Lakes Region (GLR) of the United States and Canada, and is also cultivated in flooded paddies, predominantly in California and Minnesota. A better understanding of pollen-mediated gene flow is needed within the species for both conservation and breeding efforts as cultivation occurs within the species natural range and spatially-isolated, paddy structures are limited within breeding programs. Widely cited pollen travel research in NWR demonstrated that pollen could travel at least 3200m. However, a population segregating for male sterility was used as the pollen recipient in the study and was determined to not be adequate for NWR pollen travel studies. Here, we present the characterization of a recessive white male floret (WMF) population in contrast to the dominant, purple male floret (PMF) color of cultivated NWR along with estimates of pollen-mediated gene flow in a cultivated paddy setting. Studies conducted in 2018 and 2019 revealed that the primary amount of pollen-mediated gene flow occurred within the first 7m from the PMF donor source with no gene flow detected past 63m. These results suggest that the likelihood of pollen-mediated gene flow between cultivated NWR and natural stands remains low. We also identified a strong linkage between male floret, auricle, and culm color. This study demonstrates that the WMF trait is an excellent candidate for use in pollen-mediated gene flow studies in NWR.

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

“…because of the tendency of NWR seed to break dormancy and germinate following adequate time in these submerged conditions (Berjak & Pammenter, 2008;Gietzel, 2021;Simpson, 1966). Current storage conditions were derived from the results of a number of studies regarding NWR seed.…”

“…However, in ex situ storage, seed is stored submerged in the dark at 1–3°C, seed only remains viable for 1–2 years (Grombacher et al., 1997; Oelke & Porter, 2016). As the seed is stored submerged, it begins to deteriorate, in part due to microbial populations that shift over time in storage but also because of the tendency of NWR seed to break dormancy and germinate following adequate time in these submerged conditions (Berjak & Pammenter, 2008; Gietzel, 2021; Simpson, 1966). Current storage conditions were derived from the results of a number of studies regarding NWR seed.…”