The effects and interaction of soybean maturity gene alleles controlling flowering time, maturity, and adaptation in tropical environments

Abstract

Background: Soybean is native to the temperate zones of East Asia. Poor yields of soybean in West African countries may be partially attributed to inadequate adaptation of soybean to tropical environments. Adaptation will require knowledge of the effects of allelic combinations of major maturity genes (E1, E2, and E3) and stem architecture. The long juvenile trait (J) influences soybean flowering time in short,~12 h days, which characterize tropical latitudes. Soybean plant architecture includes determinate or indeterminate stem phenotypes controlled by the Dt1 gene. Understanding the influence of these genetic components on plant development and adaptation is key to optimize phenology and improve soybean yield potential in tropical environments. Results: Soybean lines from five recombinant inbred populations were developed that varied in their combinations of targeted genes. The soybean lines were field tested in multiple environments and characterized for days to flowering (DTF), days to maturity (DTM), and plant height in locations throughout northern Ghana, and allelic combinations were determined for each line for associating genotype with phenotype. The results revealed significant differences based on genotype for DTF and DTM and allowed the comparison of different variant alleles of those genes. The mutant alleles of J and E1 had significant impact on DTF and DTM, and alleles of those genes interacted with each other for DTF but not DTM. The Dt1 gene significantly influenced plant height but not DTF or DTM.Conclusions: This research identified major and minor effect alleles of soybean genes that can be combined to control DTF, DTM, and plant height in short day tropical environments in Ghana. These phenotypes contribute to adaptation to a low latitude environment that can be optimized in a soybean breeding program with targeted selection of desired allele combinations. The knowledge of the genetic control of these traits will enhance molecular breeding to produce optimally adapted soybean varieties targeted to tropical environments.

Identifying new variation at the J locus, previously identified as e6, in long juvenile ‘Paranagoiana’ soybean

“…During amplification, it was found that the e6 lines did not produce a band for exons 3 and 4 (Fig. 2 b) similar to the non-amplification reported by Miranda et al ( 2020 ). By using TaKaRa LA Taq®, an unexpected ~10,000 bp band was produced in the new amplicons for the last 2 exons of the gene in the e6 lines, while a ~1500 bp band was seen for the wild type lines (Fig.…”

“…A recent study described a lack of amplification at the J locus in Paranagoiana and labeled it as the j−x allele. However, the study did not differentiate between both J and E6 loci (Miranda et al 2020 ).…”

“…Soybean is a short-day plant that is cultivated over latitudes ranging from 35° S to 50° N. Short days (12 h of day-length or less) allow the plant to flower and mature quickly. Phenology is delayed in long day conditions resulting in lower yields if maturity is not reached before frost, while in short days flowering can occurs early resulting in short low yielding plants (Kong et al 2014 ; Miranda et al 2020 ). Photoperiod sensitivity in soybean plays a key role in determining adaptation for a specific latitude by controlling time to flowering and maturity.…”

“…Soybean cultivation below 20° was hindered by extremely low grain yields before the discovery of the long juvenile (LJ) trait (Miranda et al 2020 ). The LJ trait, which became important in South America in the 1970s, expanded soybean production to tropical latitudes below 20˚ and even as far as the equator (Lu et al 2017 ).…”

Field-based Screening and Haplotyping of J Locus for Long Juvenile Trait in Tropical Soybean Genotypes

“…The present study mainly focused on identifying new long juvenile genotypes and verifying whether the J mutations are associated with delayed flowering in soybean. The long juvenile genetic mechanism in most tropical genotypes especially Sub-Sahara Africa is not known (Miranda et al 2020). Huaxia 3, the check variety, was introduced to some African countries and resulted in an increased productivity (Yue et al 2017).…”