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Mwakyusa L, Heredia MC, Kilasi NL, Madege RR, Herzog M, Dixit S. Screening of potential donors for anaerobic stress tolerance during germination in rice. FRONTIERS IN PLANT SCIENCE 2023; 14:1261101. [PMID: 38023850 PMCID: PMC10667690 DOI: 10.3389/fpls.2023.1261101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Accepted: 10/25/2023] [Indexed: 12/01/2023]
Abstract
The rising cost of transplanting rice has made direct seeding an affordable alternative for rice establishment, particularly in Africa. However, direct seeding, while cost-effective, faces crop establishment challenges due to flooding. Uncontrolled water, driven by erratic rains in low-lying areas or uneven fields, limit germination. Rice possesses the unique ability of anaerobic germination, enabling it to sprout and emerge in oxygen-deprived conditions. Understanding rice's response to anaerobic stress during germination is crucial for resilience breeding. Africa, although relying on direct seeding, has made limited progress in addressing flooding during germination compared to Asia. Anaerobic stress tolerance ensures successful crop emergence even in oxygen-limited environments and can help suppress weeds, a significant challenge in direct-seeded rice cultivation. This study aims to contribute by screening for potential rice donors exhibiting anaerobic stress tolerance. We screened 200 rice genotypes at Sokoine University of Agriculture (SUA) in Morogoro, Tanzania, primarily focusing on landraces with untapped potential. Using an alpha lattice design, we conducted two anaerobic experiments in September and October 2022, adding 7 cm of standing water immediately after dry seeding for flooded and maintaining a 2 cm water level after germination in the control for duration of 21 days. We identified potential donors based on selection index computed from genomic estimated breeding values (GEBVs) using eight variables: germination at 14 DAS, germination at 21 DAS, seedling height at 14 DAS, seedling height at 21 DAS, shoot dry matter at 21 DAS, root dry matter at 21 DAS, culm diameter at 21 DAS, and root length at 21DAS. Ten genotypes emerged as the most promising, exhibiting at least 70% germination in floodwater at 21 DAS and greater selection indices. These genotypes were like: Afaa Mwanza 1/159, Rojomena 271/10, Kubwa Jinga, Wahiwahi, Magongo ya Wayungu, Mpaka wa Bibi, Mwangaza, Tarabinzona, IB126-Bug 2013A, and Kanamalia with respective percentages of 75, 74, 71, 86, 75, 80, 71, 80, 70, and 73. These findings contribute to global efforts to mitigate the impacts of flooding during germination. These donors, will be potential to enrich the gene pool for anaerobic germination, providing valuable resources for breeding for flooding tolerance.
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Affiliation(s)
- Lupakisyo Mwakyusa
- Department of Crop Science and Horticulture, College of Agriculture, Sokoine University of Agriculture, Morogoro, Tanzania
- Department of Research and Innovation, Tanzania Agricultural Research Institute, Kigoma, Tanzania
| | - Maria Cristina Heredia
- Rice Breeding Innovations Department, International Rice Research Institute, Los Baños, Laguna, Philippines
| | - Newton Lwiyiso Kilasi
- Department of Crop Science and Horticulture, College of Agriculture, Sokoine University of Agriculture, Morogoro, Tanzania
| | - Richard R. Madege
- Department of Crop Science and Horticulture, College of Agriculture, Sokoine University of Agriculture, Morogoro, Tanzania
| | - Max Herzog
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Shalabh Dixit
- Rice Breeding Innovations Department, International Rice Research Institute, Los Baños, Laguna, Philippines
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Aung KM, Oo WH, Maung TZ, Min MH, Somsri A, Nam J, Kim KW, Nawade B, Lee CY, Chu SH, Park YJ. Genomic landscape of the OsTPP7 gene in its haplotype diversity and association with anaerobic germination tolerance in rice. FRONTIERS IN PLANT SCIENCE 2023; 14:1225445. [PMID: 37560030 PMCID: PMC10407808 DOI: 10.3389/fpls.2023.1225445] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Accepted: 07/07/2023] [Indexed: 08/11/2023]
Abstract
Early season flooding is a major constraint in direct-seeded rice, as rice genotypes vary in their coleoptile length during anoxia. Trehalose-6-phosphate phosphatase 7 (OsTPP7, Os09g0369400) has been identified as the genetic determinant for anaerobic germination (AG) and coleoptile elongation during flooding. We evaluated the coleoptile length of a diverse rice panel under normal and flooded conditions and investigated the Korean rice collection of 475 accessions to understand its genetic variation, population genetics, evolutionary relationships, and haplotypes in the OsTPP7 gene. Most accessions displayed enhanced flooded coleoptile lengths, with the temperate japonica ecotype exhibiting the highest average values for normal and flooded conditions. Positive Tajima's D values in indica, admixture, and tropical japonica ecotypes suggested balancing selection or population expansion. Haplotype analysis revealed 18 haplotypes, with three in cultivated accessions, 13 in the wild type, and two in both. Hap_1 was found mostly in japonica, while Hap-2 and Hap_3 were more prevalent in indica accessions. Further phenotypic performance of major haplotypes showed significant differences in flooded coleoptile length, flooding tolerance index, and shoot length between Hap_1 and Hap_2/3. These findings could be valuable for future selective rice breeding and the development of efficient haplotype-based breeding strategies for improving flood tolerance.
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Affiliation(s)
- Kyaw Myo Aung
- Department of Plant Resources, College of Industrial Sciences, Kongju National University, Yesan, Republic of Korea
| | - Win Htet Oo
- Department of Plant Resources, College of Industrial Sciences, Kongju National University, Yesan, Republic of Korea
| | - Thant Zin Maung
- Department of Plant Resources, College of Industrial Sciences, Kongju National University, Yesan, Republic of Korea
| | - Myeong-Hyeon Min
- Department of Plant Resources, College of Industrial Sciences, Kongju National University, Yesan, Republic of Korea
| | - Aueangporn Somsri
- Department of Plant Resources, College of Industrial Sciences, Kongju National University, Yesan, Republic of Korea
| | - Jungrye Nam
- Center for Crop Breeding on Omics and Artificial Intelligence, Kongju National University, Yesan, Republic of Korea
| | - Kyu-Won Kim
- Center for Crop Breeding on Omics and Artificial Intelligence, Kongju National University, Yesan, Republic of Korea
| | - Bhagwat Nawade
- Center for Crop Breeding on Omics and Artificial Intelligence, Kongju National University, Yesan, Republic of Korea
| | - Chang-Yong Lee
- Department of Industrial and Systems Engineering, College of Engineering, Kongju National University, Cheonan, Republic of Korea
| | - Sang-Ho Chu
- Center for Crop Breeding on Omics and Artificial Intelligence, Kongju National University, Yesan, Republic of Korea
| | - Yong-Jin Park
- Department of Plant Resources, College of Industrial Sciences, Kongju National University, Yesan, Republic of Korea
- Center for Crop Breeding on Omics and Artificial Intelligence, Kongju National University, Yesan, Republic of Korea
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Flooding tolerance in Rice: adaptive mechanism and marker-assisted selection breeding approaches. Mol Biol Rep 2023; 50:2795-2812. [PMID: 36592290 DOI: 10.1007/s11033-022-07853-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2022] [Revised: 08/05/2022] [Accepted: 08/10/2022] [Indexed: 01/03/2023]
Abstract
Natural and man-made ecosystems worldwide are subjected to flooding, which is a form of environmental stress. Genetic variability in the plant response to flooding involves variations in metabolism, architecture, and elongation development that are related with a low oxygen escape strategy and an opposing quiescence scheme that enables prolonged submergence endurance. Flooding is typically associated with a decrease in O2 in the cells, which is especially severe when photosynthesis is absent or limited, leading to significant annual yield losses globally. Over the past two decades, considerable advancements have been made in understanding of mechanisms of rice adaptation and tolerance to flooding/submergence. The mapping and identification of Sub1 QTL have led to the development of marker-assisted selection (MAS) breeding approach to improve flooding-tolerant rice varieties in submergence-prone ecosystems. The Sub1 incorporated in rice varieties showed tolerance during flash flood, but not during stagnant conditions. Hence, gene pyramiding techniques can be applied to combine/stack multiple resistant genes for developing flood-resilient rice varieties for different types of flooding stresses. This review contains an update on the latest advances in understanding the molecular mechanisms, metabolic adaptions, and genetic factors governing rice flooding tolerance. A better understanding of molecular genetics and adaptation mechanisms that enhance flood-tolerant varieties under different flooding regimes was also discussed.
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Panda D, Barik J, Sarkar RK. Recent Advances of Genetic Resources, Genes and Genetic Approaches for Flooding Tolerance in Rice. Curr Genomics 2021; 22:41-58. [PMID: 34045923 PMCID: PMC8142345 DOI: 10.2174/1389202922666210114104140] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2020] [Revised: 12/16/2020] [Accepted: 12/26/2020] [Indexed: 12/16/2022] Open
Abstract
Flooding is one of the most hazardous natural disasters and a major stress constraint to rice production throughout the world, which results in huge economic losses. The frequency and duration of flooding is predicted to increase in near future as a result of global climate change. Breeding of flooding tolerance in rice is a challenging task because of the complexity of the component traits, screening technique, environmental factors and genetic interactions. A great progress has been made during last two decades to find out the flooding tolerance mechanism in rice. An important breakthrough in submergence research was achieved by the identification of major quantitative trait locus (QTL) SUB1 in rice chromosomes that acts as the primary contributor for tolerance. This enabled the use of marker-assisted backcrossing (MABC) to transfer SUB1 QTL into popular varieties which showed yield advantages in flood prone areas. However, SUB1 varieties are not always tolerant to stagnant flooding and flooding during germination stage. So, gene pyramiding approach can be used by combining several important traits to develop new breeding rice lines that confer tolerances to different types of flooding. This review highlights the important germplasm/genetic resources of rice to different types of flooding stress. A brief discussion on the genes and genetic mechanism in rice exhibited to different types of flooding tolerance was discussed for the development of flood tolerant rice variety. Further research on developing multiple stresses tolerant rice can be achieved by combining SUB1 with other tolerance traits/genes for wider adaptation in the rain-fed rice ecosystems.
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Affiliation(s)
- Debabrata Panda
- Department of Biodiversity and Conservation of Natural Resources, Central University of Odisha, Koraput-764 020, Odisha, India
| | - Jijnasa Barik
- Department of Biodiversity and Conservation of Natural Resources, Central University of Odisha, Koraput-764 020, Odisha, India
| | - Ramani K Sarkar
- ICAR-National Rice Research Institute, Cuttack-753 006, Odisha, India
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Singh A, Singh Y, Mahato AK, Jayaswal PK, Singh S, Singh R, Yadav N, Singh AK, Singh PK, Singh R, Kumar R, Septiningsih EM, Balyan HS, Singh NK, Rai V. Allelic sequence variation in the Sub1A, Sub1B and Sub1C genes among diverse rice cultivars and its association with submergence tolerance. Sci Rep 2020; 10:8621. [PMID: 32451398 PMCID: PMC7248102 DOI: 10.1038/s41598-020-65588-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2017] [Accepted: 04/28/2020] [Indexed: 11/24/2022] Open
Abstract
Erratic rainfall leading to flash flooding causes huge yield losses in lowland rice. The traditional varieties and landraces of rice possess variable levels of tolerance to submergence stress, but gene discovery and utilization of these resources has been limited to the Sub1A-1 allele from variety FR13A. Therefore, we analysed the allelic sequence variation in three Sub1 genes in a panel of 179 rice genotypes and its association with submergence tolerance. Population structure and diversity analysis based on a 36-plex genome wide genic-SNP assay grouped these genotypes into two major categories representing Indica and Japonica cultivar groups with further sub-groupings into Indica, Aus, Deepwater and Aromatic-Japonica cultivars. Targetted re-sequencing of the Sub1A, Sub1B and Sub1C genes identfied 7, 7 and 38 SNPs making 8, 9 and 67 SNP haplotypes, respectively. Haplotype networks and phylogenic analysis revealed evolution of Sub1B and Sub1A genes by tandem duplication and divergence of the ancestral Sub1C gene in that order. The alleles of Sub1 genes in tolerant reference variety FR13A seem to have evolved most recently. However, no consistent association could be found between the Sub1 allelic variation and submergence tolerance probably due to low minor allele frequencies and presence of exceptions to the known Sub1A-1 association in the genotype panel. We identified 18 cultivars with non-Sub1A-1 source of submergence tolerance which after further mapping and validation in bi-parental populations will be useful for development of superior flood tolerant rice cultivars.
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Affiliation(s)
- Anuradha Singh
- ICAR-National Institute for Plant Biotechnology, Pusa Campus, New Delhi, India
- International Rice Research Institute, DAPO 7777, Metro Manila, Philippines
- Department of Genetics and Plant Breeding, Chaudhary Charan Singh University, Meerut, India
| | - Yashi Singh
- ICAR-National Institute for Plant Biotechnology, Pusa Campus, New Delhi, India
| | - Ajay K Mahato
- ICAR-National Institute for Plant Biotechnology, Pusa Campus, New Delhi, India
| | - Pawan K Jayaswal
- ICAR-National Institute for Plant Biotechnology, Pusa Campus, New Delhi, India
| | - Sangeeta Singh
- ICAR-National Institute for Plant Biotechnology, Pusa Campus, New Delhi, India
| | - Renu Singh
- ICAR-National Institute for Plant Biotechnology, Pusa Campus, New Delhi, India
| | - Neera Yadav
- ICAR-National Institute for Plant Biotechnology, Pusa Campus, New Delhi, India
| | - A K Singh
- Department of Crop Physiology, Narendra Deo University of Agriculture & Technology, Ayodhya, UP, India
| | - P K Singh
- Department of Genetics and Plant Breeding, Banaras Hindu University, Varanasi, India
| | - Rakesh Singh
- ICAR-National Bureau of Plant Genetic Resources, Pusa Campus, New Delhi, India
| | - Rajesh Kumar
- Department of Genetics and Plant Breeding, Dr. Rajendra Prasad Central Agricultural University, Samastipur, Bihar, India
| | - Endang M Septiningsih
- International Rice Research Institute, DAPO 7777, Metro Manila, Philippines
- Department of Soil and Crop Sciences, Texas A & M University, TX, 77843, USA
| | - H S Balyan
- Department of Genetics and Plant Breeding, Chaudhary Charan Singh University, Meerut, India
| | - Nagendra K Singh
- ICAR-National Institute for Plant Biotechnology, Pusa Campus, New Delhi, India
| | - Vandna Rai
- ICAR-National Institute for Plant Biotechnology, Pusa Campus, New Delhi, India.
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Fukushima A, Kuroha T, Nagai K, Hattori Y, Kobayashi M, Nishizawa T, Kojima M, Utsumi Y, Oikawa A, Seki M, Sakakibara H, Saito K, Ashikari M, Kusano M. Metabolite and Phytohormone Profiling Illustrates Metabolic Reprogramming as an Escape Strategy of Deepwater Rice during Partially Submerged Stress. Metabolites 2020; 10:metabo10020068. [PMID: 32075002 PMCID: PMC7074043 DOI: 10.3390/metabo10020068] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2019] [Revised: 02/03/2020] [Accepted: 02/11/2020] [Indexed: 02/02/2023] Open
Abstract
Rice varieties that can survive under submergence conditions respond to flooding either by enhancing internode elongation or by quiescence of shoot elongation. Despite extensive efforts to identify key metabolites triggered by complete submergence of rice possessing SUBMERGENCE 1 (SUB1) locus, metabolic responses of internode elongation of deepwater rice governed by the SNORKEL 1 and 2 genes remain elusive. This study investigated specific metabolomic responses under partial submergence (PS) to deepwater- (C9285) and non-deepwater rice cultivars (Taichung 65 (T65)). In addition, we examined the response in a near-isogenic line (NIL-12) that has a C9285 genomic fragment on chromosome 12 introgressed into the genetic background of T65. Under short-term submergence (0-24 h), metabolite profiles of C9285, NIL-12, and T65 were compared to extract significantly changed metabolites in deepwater rice under PS conditions. Comprehensive metabolite and phytohormone profiling revealed increases in metabolite levels in the glycolysis pathway in NIL-12 plants. Under long-term submergence (0-288 h), we found decreased amino acid levels. These metabolomic changes were opposite when compared to those in flood-tolerant rice with SUB1 locus. Auxin conjugate levels related to stress response decreased in NIL-12 lines relative to T65. Our analysis helped clarify the complex metabolic reprogramming in deepwater rice as an escape strategy.
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Affiliation(s)
- Atsushi Fukushima
- RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa 230-0045, Japan; (A.F.); (M.K.); (T.N.); (M.K.); (Y.U.); (A.O.); (M.S.); (H.S.); (K.S.)
| | - Takeshi Kuroha
- Bioscience and Biotechnology Center, Nagoya University, Nagoya, Aichi 464-8601, Japan; (T.K.); (K.N.); (Y.H.); (M.A.)
| | - Keisuke Nagai
- Bioscience and Biotechnology Center, Nagoya University, Nagoya, Aichi 464-8601, Japan; (T.K.); (K.N.); (Y.H.); (M.A.)
| | - Yoko Hattori
- Bioscience and Biotechnology Center, Nagoya University, Nagoya, Aichi 464-8601, Japan; (T.K.); (K.N.); (Y.H.); (M.A.)
| | - Makoto Kobayashi
- RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa 230-0045, Japan; (A.F.); (M.K.); (T.N.); (M.K.); (Y.U.); (A.O.); (M.S.); (H.S.); (K.S.)
| | - Tomoko Nishizawa
- RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa 230-0045, Japan; (A.F.); (M.K.); (T.N.); (M.K.); (Y.U.); (A.O.); (M.S.); (H.S.); (K.S.)
| | - Mikiko Kojima
- RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa 230-0045, Japan; (A.F.); (M.K.); (T.N.); (M.K.); (Y.U.); (A.O.); (M.S.); (H.S.); (K.S.)
| | - Yoshinori Utsumi
- RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa 230-0045, Japan; (A.F.); (M.K.); (T.N.); (M.K.); (Y.U.); (A.O.); (M.S.); (H.S.); (K.S.)
| | - Akira Oikawa
- RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa 230-0045, Japan; (A.F.); (M.K.); (T.N.); (M.K.); (Y.U.); (A.O.); (M.S.); (H.S.); (K.S.)
- Faculty of Agriculture, Yamagata University, Tsuruoka, Yamagata 997-8555, Japan
| | - Motoaki Seki
- RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa 230-0045, Japan; (A.F.); (M.K.); (T.N.); (M.K.); (Y.U.); (A.O.); (M.S.); (H.S.); (K.S.)
| | - Hitoshi Sakakibara
- RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa 230-0045, Japan; (A.F.); (M.K.); (T.N.); (M.K.); (Y.U.); (A.O.); (M.S.); (H.S.); (K.S.)
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Aichi 464-8601, Japan
| | - Kazuki Saito
- RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa 230-0045, Japan; (A.F.); (M.K.); (T.N.); (M.K.); (Y.U.); (A.O.); (M.S.); (H.S.); (K.S.)
- Graduate School of Pharmaceutical Sciences, Chiba University, Chuo-ku, Chiba 263-8522, Japan
| | - Motoyuki Ashikari
- Bioscience and Biotechnology Center, Nagoya University, Nagoya, Aichi 464-8601, Japan; (T.K.); (K.N.); (Y.H.); (M.A.)
| | - Miyako Kusano
- RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa 230-0045, Japan; (A.F.); (M.K.); (T.N.); (M.K.); (Y.U.); (A.O.); (M.S.); (H.S.); (K.S.)
- Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba, Ibaraki 305-8572, Japan
- Tsukuba Plant Innovation Research Center, University of Tsukuba, Tsukuba, Ibaraki 305-8572, Japan
- Correspondence:
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Identification of stable QTLs and candidate genes involved in anaerobic germination tolerance in rice via high-density genetic mapping and RNA-Seq. BMC Genomics 2019; 20:355. [PMID: 31072298 PMCID: PMC6506967 DOI: 10.1186/s12864-019-5741-y] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Accepted: 04/26/2019] [Indexed: 12/25/2022] Open
Abstract
Background Anaerobic germination tolerance is an important trait for direct-seeded rice varieties. Understanding the genetic basis of anaerobic germination is a key for breeding direct-seeded rice varieties. Results In this study, a recombinant inbred line (RIL) population derived from a cross between YZX and 02428 exhibited obvious coleoptile phenotypic differences. Mapping analysis using a high-density bin map indicated that a total of 25 loci were detected across two cropping seasons, including 10 previously detected loci and a total of 13 stable loci. Analysis of the 13 stable loci demonstrated that the more elite alleles that were pyramided in an individual, the higher the values of these traits were in the two cropping seasons. Furthermore, some anaerobic germination-tolerant recombinant inbred lines, namely G9, G10, G16, and G151, were identified. A total of 84 differentially expressed genes were obtained from the 13 stable loci via genome-wide expression analysis of the two parents at three key periods. Among them, Os06g0110200, Os07g0638300, Os07g0638400, Os09g0532900, Os09g0531701 and Os12g0539751 constitute the best candidates associated with anaerobic germination. Conclusions Both the anaerobic germination-tolerant recombinant inbred lines and the loci identified in this study will provide new genetic resources for improving the anaerobic germination tolerance of rice using molecular breeding strategies, as well as will broaden our understanding of the genetic control of germination tolerance under anaerobic conditions. Electronic supplementary material The online version of this article (10.1186/s12864-019-5741-y) contains supplementary material, which is available to authorized users.
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Abstract
A major problem of climate change is the increasing duration and frequency of heavy rainfall events. This leads to soil flooding that negatively affects plant growth, eventually leading to death of plants if the flooding persists for several days. Most crop plants are very sensitive to flooding, and dramatic yield losses occur due to flooding each year. This review summarizes recent progress and approaches to enhance crop resistance to flooding. Most experiments have been done on maize, barley, and soybean. Work on other crops such as wheat and rape has only started. The most promising traits that might enhance crop flooding tolerance are anatomical adaptations such as aerenchyma formation, the formation of a barrier against radial oxygen loss, and the growth of adventitious roots. Metabolic adaptations might be able to improve waterlogging tolerance as well, but more studies are needed in this direction. Reasonable approaches for future studies are quantitative trait locus (QTL) analyses or genome-wide association (GWA) studies in combination with specific tolerance traits that can be easily assessed. The usage of flooding-tolerant relatives or ancestral cultivars of the crop of interest in these experiments might enhance the chances of finding useful tolerance traits to be used in breeding.
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