A rice small GTPase, Rab6a, is involved in the regulation of grain yield and iron nutrition in response to CO2 enrichment

Abstract

Despite extensive studies on the effects of elevated atmospheric CO2 concentrations ([CO2]) on rice, the molecular mechanisms and signaling events underlying the adaptation of plants remain largely elusive. Here, we report that OsRab6a, which encodes a small GTPase, is involved in the regulation of rice growth, grain yield, and accumulation of iron (Fe) in response to elevated [CO2] (e[CO2]). We generated transgenic plants with OsRab6a-overexpression (-OE) together with OsRab6a-RNAi lines, and found no differences in growth and grain yield among them and wild-type (WT) plants under ambient [CO2] conditions. Under e[CO2] conditions, growth and grain yield of the WT and OsRab6a-OE plants were enhanced, with a greater effect being observed in the latter. In contrast, there were no effects of e[CO2] on growth and grain yield of the OsRab6a-RNAi plants. Photosynthetic rates in both the WT and OsRab6a-OE plants were stimulated by e[CO2], with the magnitude of the increase being higher in OsRab6a-OE plants. Fe concentrations in vegetative tissues and the grain of the WT and transgenic plants were reduced by e[CO2], and the magnitude of the decrease was lower in the OE plants than in the WT and RNAi plants. Genes associated with Fe acquisition in the OsRab6a-OE lines exhibited higher levels of expression than those in the WT and the RNAi lines under e[CO2]. Analysis of our data using Dunnett’s multiple comparison test suggested that OsRab6a is an important molecular regulator that underlies the adaptation of rice to e[CO2] by controlling photosynthesis and Fe accumulation.

G protein γ subunit qPE9-1 is involved in rice adaptation under elevated CO2 concentration by regulating leaf photosynthesis

“…4 A), which suggests that qPE9-1 may be involved in A net regulation under eCO 2 . Our results are consistent with the observation in GTPase Rab6a overexpression rice plants, which suggests great potential of Rab6a in increasing rice A net under eCO 2 (Yang et al 2020 ). Plant biomass is a complex trait and can be affected by many factors (Xing and Zhang 2010 ).…”

“…Numerous studies have been evaluated the responses of crops to eCO 2 (Kim et al 2003 ; Ainsworth 2008 ; Yang et al 2007 , 2020 ; Zhu et al 2014 ; Xu et al 2019 ; Becklin et al 2017 ), but the role of qPE9-1 in response to eCO 2 remains unexplored. In the present study, we determined that G protein γ-subunit qPE9-1 played a positive role in rice growth under eCO 2 by regulating A net and Rubisco content in leaves.…”

“…G proteins are important signaling components in plants, which are involved in plant development and environmental responses (Urano and Jones 2014 ). Rice small GTPase, OsRab6a , which encodes monomeric G proteins related to the α-subunit of G proteins, played a positive role in rice growth under eCO 2 conditions (Yang et al 2020 ). So, based on this, we hypothesized that G protein γ-subunit qPE9-1 might be involved in response to eCO 2 .…”

“…SCRM2 and CDKB1 regulated stomatal patterning in response to eCO 2 (Watson-Lazowski et al 2016 ). Lastly, a rice small GTPase, Rab6a , encodes a monomeric G protein related to the α-subunit of G proteins and is involved in the regulation of grain yield in response to eCO 2 (Yang et al 2020 ). Overexpression of OsRab6a significantly increased rice net photosynthetic rate, biomass and grain yield under eCO 2 condition.…”

Mining of Potential Gene Resources for Breeding Nutritionally Improved Maize

“…Many TFs have been found to regulate Fe uptake and transport from different plant species, including IRO2 [ 103 ], OsbHLH58 [ 104 ], OsbHLH59 [ 104 ], AtbHLH29 [ 105 ], GmbHLH300 [ 106 ], IDEF1 [ 107 ] and CSN6 complex [ 108 ]. In addition, Rab6a, as a subunit of small GTPase, is involved in adaption to CO 2 enrichment, thereby regulating photosynthesis and Fe content [ 109 ]. Fe-binding ubiquitin ligase (HRZ) is associated with the negative regulation of the Fe transport pathway [ 110 ].…”