SUB1A‐dependent and ‐independent mechanisms are involved in the flooding tolerance of wild rice species

Abstract

Crop tolerance to flooding is an important agronomic trait. Although rice (Oryza sativa) is considered a flood-tolerant crop, only limited cultivars display tolerance to prolonged submergence, which is largely attributed to the presence of the SUB1A gene. Wild Oryza species have the potential to unveil adaptive mechanisms and shed light on the basis of submergence tolerance traits. In this study, we screened 109 Oryza genotypes belonging to different rice genome groups for flooding tolerance. Oryza nivara and Oryza rufipogon accessions, belonging to the A-genome group, together with Oryza sativa, showed a wide range of submergence responses, and the tolerance-related SUB1A-1 and the intolerance-related SUB1A-2 alleles were found in tolerant and sensitive accessions, respectively. Flooding-tolerant accessions of Oryza rhizomatis and Oryza eichingeri, belonging to the C-genome group, were also identified. Interestingly, SUB1A was absent in these species, which possess a SUB1 orthologue with high similarity to O. sativa SUB1C. The expression patterns of submergence-induced genes in these rice genotypes indicated limited induction of anaerobic genes, with classical anaerobic proteins poorly induced in O. rhizomatis under submergence. The results indicated that SUB1A-1 is not essential to confer submergence tolerance in the wild rice genotypes belonging to the C-genome group, which show instead a SUB1A-independent response to submergence.

Waterlogging and submergence stress: affects and acclimation

“…Intolerant varieties lacking Sub1A display ethylene-mediated ABA degradation, GA responsiveness and fast elongation under flooding under Sub1C regulation (Fukao & Bailey-Serres, 2008;Kudahettige et al, 2010;Pena-Castro et al, 2011). Some wild-type rice genotypes (O. rhizomatis and O. eichingeri belonging to C-genome group) lacking SUB1A also show reduced growth and submergence tolerance indicating a SUB1A-independent tolerance mechanism (Niroula et al, 2012). Ethylene also mediates upregulation of EIN3 (involved in ethylene biosynthesis) which directly binds to SNORKEL1 (SK1) and SNORKEL2 that triggers considerable internode elongation via ethylene and GA (Hattori et al, 2009;Nagai et al, 2010).…”

Genetic mechanisms of abiotic stress tolerance that translate to crop yield stability

“…Fine mapping of SUB1 identified a genetically varied chromosomal region, which harbours two or three genes encoding ethylene-response factor (ERF) DNAbinding proteins 14 (FIG. 1b), arising from gene CNV and neofunctionalization that apparently predates domestication 15 . Of the three ERFs at the SUB1 locus (SUB1A, SUB1B and SUB1C), only the strongly submergenceinduced allele SUB1A-1 is limited to submergence-tolerant landraces 14,16 .…”

Expression of Root-Related Transcription Factors Associated with Flooding Tolerance of Soybean (Glycine max)

“…During the last two decades, much research has been conducted on the molecular, biochemical and physiological responses of plants to the lack of oxygen, but relatively little information is available regarding the responses to soil flooding per se [6,7,8,9,10,11,12,13,14]. A significant change in the protein synthesis in roots occurs during anaerobiosis [15,16,17]. Most of the identified anaerobic proteins (ANPs) are enzymes involved in sugar metabolism, glycolysis and fermentation [18,19,20,21,22,23,24,25].…”