Utilization of plant architecture genes in soybean to positively impact adaptation to high yield environments

Authors: KIM, JEONG-HWA - University Of Missouri; SCABOO, ANDREW - University Of Missouri; PANTALONE, VINCENT - University Of Tennessee; LI, ZENGLU - University Of Georgia; Bilyeu, Kristin

Submitted to: Frontiers in Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/20/2022
Publication Date: 5/24/2022
Citation: Kim, J., Scaboo, A., Pantalone, V., Li, Z., Bilyeu, K.D. 2022. Utilization of plant architecture genes in soybean to positively impact adaptation to high yield environments. Frontiers in Plant Science. 13. Article 891587. https://doi.org/10.3389/fpls.2022.891587.
DOI: https://doi.org/10.3389/fpls.2022.891587

Interpretive Summary: Two major soybean stem termination types are currently utilized to maximize harvestable yield by modifying overall plant architecture of soybean; soybeans are indeterminate in northern production zones and determinate southern production zones in the United States. Determinate soybeans have fewer pod-forming nodes but resist lodging and thus protect harvestable yields under long production seasons. To identify new avenues for yield increase while maintaining lodging resistance, we characterized the previously underutilized soybean stem termination types, tall determinate and semi-determinate, in the genetic context applicable to southern production zones in the United States. The results revealed the exact changes in the gene that controls the tall determinate stem architecture types. New soybean germplasm lines with combinations of maturity genes with different stem termination genes were developed and tested in one northern and two southern production zones. Importantly, tall determinate soybean germplasm adapted to southern production zones produced more pod bearing nodes than the typical determinate types. The lodging resistance results were more complicated and will require additional study to distinguish the effects of the different plant architecture types. The impact of this work is a “Green Revolution” avenue to efficiently design tall determinate soybeans with the potential to increase yields.

Technical Abstract: Optimization of plant architecture by modifying stem termination and timing of flowering and maturity of soybean is a promising strategy to improve its adaptability to specific production environments. Therefore, it is important to choose a proper stem termination type and to understand morphological differences between each stem termination type under various environmental conditions. Variations in abruptness of stem termination have been generally classified into three classical genetic types, indeterminate (Dt1), determinate (dt1), and semi-determinate (Dt2). However, an additional stem termination type, termed tall determinate, and its genetic symbol, dt1-t, were introduced about 25 years ago. The tall determinate soybean lines show delayed cessation of apical stem growth and about 50% taller plant heights than the typical determinate soybeans, even though the genetic control of the tall determinate phenotype was found to be allelic to dt1. Despite the potential agronomic merits of the alternative stem termination type, knowledge about the tall determinate soybean remains limited. We clarified the molecular basis of the tall determinate stem termination type and examined potential agronomic merits of the alternative stem type under three different production environments in the US. Sequence analysis of the classical tall determinate soybean lines revealed that the dt1-t allele responsible for tall determinate stem architecture is caused by two of the identified independent missense alleles of dt1, dt1-t1 (R130K), and dt1-t2 (R62S). Also, from the comparison among soybean accessions belonging to each of the genotype categories for stem termination types, soybean accessions with tall determinate alleles were found to have a high discrepancy rate in phenotyping. Newly developed tall determinate late-maturing soybean germplasm lines had taller plant heights and a greater number of nodes with a similar stem diameter and similar pod density at the apical stem compared to typical determinate soybeans having dt1 (R166W) alleles in Southern environments in the US. The phenotype of increased pod-bearing nodes with lodging resistance has the potential to improve yield, especially grown in high yield environments. This study suggests an alternative strategy to remodel the shape of soybean plants, which can possibly lead to yield improvement through the modification of soybean plant architecture.