Development of Aluminium (Al)-Tolerant Soybean Using Molecular Tools: Limitations and Future Directions

Soybean is one of the most significant oilseed and vital food crops. Soybean growth and yield have been significantly affected by abiotic stresses. Heavy metal stress like Al toxicity is the most serious threat to soybean growth and yield and impairs plant growth and development. To counter the toxic effect of Al stress, breeders have used different breeding tools, including conventional breeding techniques, but the success ratio of these tools is limited because of the complex genetic mechanism of Al tolerance. Due to advancements in molecular biology, researchers have identified many potential genes and quantitative trait loci (QTL) involved in soybean response to Al stress. Some were successfully cloned and transformed to develop Al-resilient soybean genotypes. Genetic diversity has played a key role in improving the plant breeding program. Unfortunately, due to genetic erosion, the beneficial alleles have been threatened, and hence, significant efforts should be done to safeguard the plant germplasm for future use. As mentioned in this review, potential molecular techniques like transcription factors (TFs) and genetic engineering have been used to identify the molecular factors regulating Al tolerance and the development of transgenic soybean cultivars. The clustered regularly interspaced short palindromic repeats (CRISPR/Cas9) technique has been developed, which can alter the desired gene to bring targeted results in soybean, but it has not been broadly used to amend the Al-tolerant genes in soybean. Despite all these efforts, the Al tolerance mechanism has not been fully explored. Hence, more efforts are needed to adopt a more useful way to breed the Al-tolerant cultivars by targeting the identified genes/QTL, as mentioned in this review. This review will be a significant piece of information for future researchers to understand the genetic mechanism of Al tolerance in soybean.

Automated summary

Soybean, a significant oilseed and food crop, is vulnerable to abiotic stresses, with aluminum toxicity being the most serious threat. Advances in molecular biology have identified potential genes and QTL involved in soybean response to aluminum stress, but genetic erosion poses a risk to the beneficial alleles. Molecular techniques like transcription factors and genetic engineering have been used, but the understanding of aluminum tolerance mechanism is still incomplete. More efforts should be made to breed aluminum-tolerant cultivars by targeting the identified genes/QTL.