Abstract
Flooding is an important strategy for weed control in paddy rice fields. However, terrestrial weeds had evolved mechanisms of tolerance to flooding, resulting in new ‘snorkeling’ ecotypes. The aim of this review is to discuss the mechanisms of flooding tolerance in cultivated and weedy rice at different plant stages and the putative utility of this trait for weed management. Knowledge about flooding tolerance is derived primarily from crop models, mainly rice. The rice model informs us about the possible flooding tolerance mechanisms in weedy rice, Echinochloa species, and other weeds. During germination, the gene related to carbohydrate mobilization and energy intake (RAmy3D), and genes involved in metabolism maintenance under anoxia (ADH, PDC, and OsB12D1) are the most important for flooding tolerance. Flooding tolerance during emergence involved responses promoted by ethylene and induction of RAmy3D, ADH, PDC, and OsB12D1. Plant species tolerant to complete submersion also employ escape strategies or the ability to become quiescent during the submergence period. In weedy rice, the expression of PDC1, SUS3, and SUB1 genes is not directly related to flooding tolerance, contrary to what was learned in cultivated rice. Mitigation of flooding tolerance in weeds could be achieved with biotechnological approaches and genetic manipulation of flood tolerance genes through RNAi and transposons, providing a potential new tool for weed management.
Highlights
Partial or complete flooding hampers fundamental plant processes, such as respiration and photosynthesis, because of low oxygen (O2 ) diffusion in water
This flood adaptation is described as low O2 escape syndrome (LOES), induced by ethylene accumulation and regulated by SNORKEL (SK) locus which induces the production of gibberellic acid and auxin [20]
There is a large diversity of strategies for flooding tolerance in rice across several stages of plant development
Summary
Partial or complete flooding hampers fundamental plant processes, such as respiration and photosynthesis, because of low oxygen (O2 ) diffusion in water. Current advances in biotechnology present the possibility of using molecular tools to understand flooding tolerance, and manipulate DNA and RNA for the development of modern snorkeling weed control methods [14,15]. The gene silencing process has been pursued as an advanced biotechnological tool to reduce the gene flow consequences of transgenic crops [16], such as rice to weedy rice, sugar beet to wild beet, sorghum to johnsongrass, and canola to wild mustard [17,18]. The objectives of this review are to digest the current knowledge about the main mechanisms of flooding tolerance in cultivated and weedy rice at different plant stages and to present its putative utility for weed control
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