Some Accessions of Amazonian Wild Rice (Oryza glumaepatula) Constitutively Form a Barrier to Radial Oxygen Loss along Adventitious Roots under Aerated Conditions

Abstract

A barrier to radial oxygen loss (ROL), which reduces the loss of oxygen transported via the aerenchyma to the root tips, enables the roots of wetland plants to grow into anoxic/hypoxic waterlogged soil. However, little is known about its genetic regulation. Quantitative trait loci (QTLs) mapping can help to understand the factors that regulate barrier formation. Rice (Oryza sativa) inducibly forms an ROL barrier under stagnant conditions, while a few wetland plants constitutively form one under aerated conditions. Here, we evaluated the formation of a constitutive ROL barrier in a total of four accessions from two wild rice species. Three of the accessions were wetland accessions of O. glumaepatula, and the fourth was a non-wetland species of O. rufipogon. These species have an AA type genome, which allows them to be crossed with cultivated rice. The three O. glumaepatula accessions (W2165, W2149, and W1183) formed an ROL barrier under aerated conditions. The O. rufipogon accession (W1962) did not form a constitutive ROL barrier, but it formed an inducible ROL barrier under stagnant conditions. The three O. glumaepatula accessions should be useful for QTL mapping to understand how a constitutive ROL barrier forms. The constitutive barrier of W2165 was closely associated with suberization and resistance to penetration by an apoplastic tracer (periodic acid) at the exodermis but did not include lignin at the sclerenchyma.

Comparative study on anatomical traits and gas exchange responses due to belowground hypoxic stress and thermal stress in three tropical seagrasses

“…Anatomical structure acting as a ROL barrier observed as an accumulation of suberin or lignin at the middle lamella of subepidermal layers termed exodermis has been identified in the seagrasses, Halophila ovalis , Cymodocea rotundata and Zostera marina ( Pedersen et al, 1998 ; Connell, Colmer & Walker, 1999 ; Holmer & Bondgaard, 2001 ; Sand-Jensen et al, 2005 ). These aerenchyma networks and ROL barriers have also been found in other wetland plants ( Armstrong, 1971 ; Pi et al, 2009 ; Lemoine et al, 2012 ; Collier & Waycott, 2014 ; Chorchuhirun, Kraichak & Kermanee, 2020 ; Ejiri, Sawazaki & Shiono, 2020 ; Tatongjai, Kraichak & Kermanee, 2021 ) and certain crop species, such as taro and rice ( Abiko & Miyasaka, 2020 ; Mei et al, 2020 ).…”

Abscisic acid is required for exodermal suberization to form a barrier to radial oxygen loss in the adventitious roots of rice (Oryza sativa)

“…Rice grown under aerated conditions in the absence of exogenous ABA does not form suberin lamellae in the exodermis (Colmer et al ., 1998; Colmer, 2003a; Shiono et al ., 2011, 2014a; Ejiri et al ., 2020). However, the present results show that exogenous ABA induces suberin lamellae in the exodermis (by qualitative histochemical staining; Figs 3, S8) and promotes suberin monomer accumulations in the OPRs (by quantitative GC‐based analysis; Figs 2(e,f), 3(d,e); Table S2) in wild‐type rice grown under aerated conditions.…”

“…Radial oxygen loss barriers are located at the outer part of roots (OPRs) exterior to the aerenchyma (Nishiuchi et al ., 2012; Yamauchi et al ., 2018). Their main component is thought to be suberin in a variety of species including Amazonian trees (De Simone et al ., 2003), Phragmites australis (Armstrong et al ., 2000; Soukup et al ., 2007), Echinochloa wild species (Ejiri & Shiono, 2019), Oryza glumaepatula accession W2165 (Ejiri et al ., 2020) and rice (Kulichikhin et al ., 2014; Shiono et al ., 2014b; Colmer et al ., 2019). Suberin lamellae are composed of aromatic and aliphatic suberin monomers in the exodermal cell walls (Schreiber & Franke, 2011; Kreszies et al ., 2018).…”

Expression analysis of genes for cytochrome P450 CYP86 and glycerol-3-phosphate acyltransferase related to suberin biosynthesis in rice roots under stagnant deoxygenated conditions

“…All suberin-stained sections were photographed with a fluorescence microscope with the following settings [Exposure time: 50 msec; ISO: 400] with same laser power for excitation. Our method is based on the procedure outlined in Ejiri et al (2020), with two minor modifications: changing the size of region-of-interest (ROI) and handling background values. The original 12-bit color images were split into red, green, and blue channels and the yellow intensity was calculated as the sum of the red and green intensities minus the blue intensity.…”