A transcription factor STOP1-centered pathway coordinates ammonium and phosphate acquisition in Arabidopsis

Phosphorus(P)is an indispensable macronutrient required for plant growth and development.Natural phosphate(Pi)reserves are finite,and a better understanding of Pi utilization by crops is therefore vital for worldwide food security.Ammonium has long been known to enhance Pi acquisition efficiency in agriculture;however,the molecular mechanisms coordinating Pi nutrition and ammonium remains unclear.Here,we reveal that ammonium is a novel initiator that stimulates the accumulation of a key regulatory protein,STOP1,in the nuclei of Arabidopsis root cells under Pi deficiency.We show that Pi deficiency promotes ammonium uptake mediated by AMT1 transporters and causes rapid acidification of the root surface.Rhizosphere acidification-triggered STOP1 accumulation activates the excretion of organic acids,which help to solubilize Pi from insoluble iron or calcium phosphates.Ammonium uptake by AMT1 transporters is downregulated by a CIPK23 protein kinase whose expression is directly modulated by STOP1 when ammonium reaches toxic levels.Taken together,we have identified a STOP1-centered regulatory network that links external ammonium with efficient Pi acquisition from insoluble phosphate sources.These findings provide a framework for developing possible strategies to improve crop production by enhancing the utilization of non-bioavailable nutrients in soil.

Understandings and future challenges in soybean functional genomics and molecular breeding

Soybean(Glycine max)is a major source of plant protein and oil.Soybean breeding has benefited from advances in functional genomics.In particular,the release of soybean reference genomes has advanced our understanding of soybean adaptation to soil nutrient deficiencies,the molecular mechanism of symbiotic nitrogen(N)fixation,biotic and abiotic stress tolerance,and the roles of flowering time in regional adaptation,plant architecture,and seed yield and quality.Nevertheless,many challenges remain for soybean functional genomics and molecular breeding,mainly related to improving grain yield through high-density planting,maize-soybean intercropping,taking advantage of wild resources,utilization of heterosis,genomic prediction and selection breeding,and precise breeding through genome editing.This review summarizes the current progress in soybean functional genomics and directs future challenges for molecular breeding of soybean.