Identification and characterization of novel QTL conferring internal detoxification of aluminium in soybean

Authors: LI, YANG - Nanjing Agricultural University; YE, HENG - University Of Missouri; SONG, LI - University Of Missouri; VUONG, TRI - University Of Missouri; Song, Qijian; ZHAO, LIJUAN - Nanjing Agricultural University; SHANNON, J. GROVER - University Of Missouri; LI, YAN - Nanjing Agricultural University; NGUYEN, HENRY - University Of Missouri

Submitted to: Journal of Experimental Botany
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/9/2021
Publication Date: 4/24/2021
Citation: Li, Y., Ye, H., Song, L., Vuong, T.D., Song, Q., Zhao, L., Shannon, J., Li, Y., Nguyen, H.T. 2021. Identification and characterization of novel QTL conferring internal detoxification of aluminium in soybean. Journal of Experimental Botany. 72(13):4993-5009. https://doi.org/10.1093/jxb/erab168.
DOI: https://doi.org/10.1093/jxb/erab168

Interpretive Summary: Earth's crust consists of 8% aluminum, mostly as harmless oxides and aluminosilicates. In acidic soil, however, aluminum can be solubilized into forms toxic to plants. Aluminum toxicity interferes with nutrient and water absorption, disrupts calcium homeostasis, inhibits root elongation and lateral root initiation and consequently reduces crop yield or causes plant death. Genes that help alleviate aluminum toxicity have been studied in model plants like Arabidopsis and rice but not in soybean. In this research, we identified aluminum tolerant soybean genetic resources and found two novel aluminum tolerance genes. We conclude that aluminum tolerance resulted from leaf tissue tolerance instead of aluminum exclusion or transport alteration. The soybeans and novel genes controlling aluminum tolerance are expected to provide breeders at private and public sectors new resources to help eliminate the effects of aluminum toxicity on commercial soybean production.

Technical Abstract: Aluminum (Al) toxicity is a serious abiotic stress limiting crop yield. Al toxicity inhibits plant root growth, leading to insufficient water and nutrient uptake. Soybean is sensitive to Al toxicity, exhibiting impaired root growth under elevated Al3+ concentrations. In this research, two soybean lines (Magellan and PI567731) differing in Al tolerance represented by primary root length ratio (PRL_Ratio), total root length ratio (TRL_Ratio), and root tip number ratio (RTN_Ratio) under Al stress were identified. Quantitative trait loci (QTL) mapping using a recombinant inbred line (RIL) population derived from these two lines detected three QTLs on chromosomes 3, 13, and 20 with Al tolerant-alleles from varietty "Magellan". qAL_Gm13 and qAL_Gm20 explained relatively large variations and mainly played roles in maintaining root elongation; while, qAl_Gm03 was mapped to be involved in maintaining root initiation under Al stress. This result suggested the importance of recruiting TRL and RTN traits in Al tolerance studies. Furthermore, qAl_Gm13 and qAL_Gm20 were confirmed in near-isogenic line (NIL) backgrounds and shown to epistatically regulate Al tolerance in tissue tolerance pathways instead of Al3+ exclusion or transport. The phylogenetic and pedigree analysis identified the tolerant alleles of both loci came from the US ancestor line, A.K.[FC30761] (PI 548297) originally from acidic soils in the northeast of China and close to North Korea. Our results provided novel genetic resources for breeding Al tolerant soybeans and confirmed Al tolerance QTLs in the NIL backgrounds and proposed Al3+ tissue tolerance underlying the natural variations in soybean for the first time.