Identification of Functional Genetic Variations Underlying Flooding Tolerance in Brazilian Soybean Genotypes

Area of Science:

• Plant Science
• Genetics
• Agronomy

Background:

• Flooding is a major environmental stress impacting soybean (Glycine max) yield globally, particularly in lowland cultivation areas.
• Soybean is often rotated with rice (Oryza sativa) in these regions, necessitating varieties resilient to waterlogged conditions.

Purpose of the Study:

• To characterize physiological responses to flooding stress in Brazilian soybean genotypes.
• To identify differentially expressed genes and single nucleotide polymorphisms (SNPs) associated with flooding tolerance.
• To select promising SNPs for marker-assisted selection to develop flood-tolerant soybean.

Main Methods:

• RNA sequencing was performed on flooding-stressed soybean cultivars (TECIRGA 6070 - tolerant, FUNDACEP 62 - sensitive) at the V6 stage.
• Gene expression analysis identified induced and repressed genes, with a focus on those exclusively regulated in the tolerant genotype.
• SNP identification within differentially expressed genes was followed by KASP assay validation and field trials with 166 Brazilian soybean genotypes.

Main Results:

• A total of 421 induced and 291 repressed genes were identified. The tolerant genotype showed 284 up- and 460 down-regulated genes.
• 100 and 148 genes were exclusively up- and down-regulated, respectively, in the tolerant soybean cultivar.
• 38 SNPs in abiotic stress-responsive genes were found in the tolerant genotype and absent in the sensitive one. Five SNPs were identified as potentially related to flooding tolerance.

Conclusions:

• This study provides valuable insights into the genetic basis of soybean flooding tolerance.
• Identified genes and SNPs can be utilized for marker-assisted selection to breed soybean varieties better adapted to poorly drained or flood-prone soils.
• The findings contribute to developing more resilient soybean production systems in affected regions worldwide.