GmPTF1 modifies root architecture responses to phosphate starvation primarily through regulating GmEXPB2 expression in soybean

Abstract

Summary Though root architecture modifications may be critically important for improving phosphorus (P) efficiency in crops, the regulatory mechanisms triggering these changes remain unclear. In this study, we demonstrate that genotypic variation in GmEXPB2 expression is strongly correlated with root elongation and P acquisition efficiency, and enhancing its transcription significantly improves soybean yield in the field. Promoter deletion analysis was performed using 5′ truncation fragments (P1–P6) of GmEXPB2 fused with the GUS gene in soybean transgenic hairy roots, which revealed that the P1 segment containing three E‐box elements significantly enhances induction of gene expression in response to phosphate (Pi) starvation. Further experimentation demonstrated that GmPTF1, a basic‐helix‐loop‐helix transcription factor, is the regulatory factor responsible for the induction of GmEXPB2 expression in response to Pi starvation. In short, Pi starvation induced expression of GmPTF1, with the GmPTF1 product directly binding to the E‐box motif in the P1 region of the GmEXPB2 promoter. Plus, both GmPTF1 and GmEXPB2 highly expressed in lateral roots, and were significantly enhanced by P deficiency. Further work with soybean stable transgenic plants through RNA sequencing analysis showed that altering GmPTF1 expression significantly impacted the transcription of a series of cell wall genes, including GmEXPB2, and thereby affected root growth, biomass and P uptake. Taken together, this work identifies a novel regulatory factor, GmPTF1, involved in changing soybean root architecture partially through regulation of the expression of GmEXPB2 by binding the E‐box motif in its promoter region.

Overexpression of AcEXPA23 Promotes Lateral Root Development in Kiwifruit

“…In this study, transformation experiments demonstrated that overexpression of AcEXPA23 could significantly enhance the number of lateral roots in kiwifruit ( Figure 7 and Figure 8 ), which was in line with findings of previous studies [ 18 , 57 , 58 , 59 , 60 ]. A recent study on maize yield found that 48% of the yield gain was associated with a decadal climate trend, 39% with agronomic improvements, and only 13% with improvement in genetic yield potential [ 61 ].…”

Cooperative interactions between nitrogen fixation and phosphorus nutrition in legumes

“…By contrast, limited carbohydrates are mostly invested in roots but not in nodules, for acquiring more P directly from soils when P deficient and/or N sufficient. Thereby, increasing root : shoot ratios in low P while reducing nodulation and decreasing SNF efficiency in sufficient N are usually observed (Høgh‐Jensen et al ., 2002; Kleinert et al ., 2014; Li et al ., 2015; Chen & Liao, 2017; Yang et al ., 2021). Under both P‐ and N‐deficient conditions, large amounts of carbohydrates are allocated to both roots and nodules, resulting in the inhibition of the whole plant growth (Hu et al ., 2019; Ueda & Yanagisawa, 2019).…”

“…For example, GmPAP12 and acid phosphatase gene GmACP1 involved in P cycling and nodule P homeostasis under P‐deficiency conditions might be the targets for the improvement of SNF (Zhang et al ., 2014, 2017; Li et al ., 2017). It has been demonstrated that the overexpression of genes involved in root growth or nodule development such as GmPTF1 , GmEXPB2 , and GmINS1 enhanced SNF and yield (Li et al ., 2015, 2018; Yang et al ., 2021). In addition, overexpression of GmSPX5 increased nodule number and nodule size and thus increased SNF efficiency (Xue et al ., 2017; Lu et al ., 2020; Zhuang et al ., 2021), demonstrating that they also could be good targets for the improvement of P use efficiency and SNF.…”

GmEIL4 enhances soybean (Glycine max) phosphorus efficiency by improving root system development

“…Wang et al, 2020), GmPTF1 (Z. Yang, Gao, et al, 2021), and GmETO1 (H. Zhang et al, 2020), few QTLs have been applied in soybean production. Therefore, it is far from enough to elucidate the regulatory mechanism of soybean P use efficiency.…”

“…Soybean P efficiency is a complex quantitative trait regulated by multiple genes (D. Zhang, Song, et al, 2014). Although many quantitative trait loci (QTLs) related to P efficiency have been reported and some genes have been studied, such as GmACP2 (D. Zhang et al, 2017), GmPAP12 (Y. Wang et al, 2020), GmPTF1 (Z. Yang, Gao, et al, 2021), and GmETO1 (H. Zhang et al, 2020), few QTLs have been applied in soybean production. Therefore, it is far from enough to elucidate the regulatory mechanism of soybean P use efficiency.…”