PIF4 interacts with ABI4 to serve as a transcriptional activator complex to promote seed dormancy by enhancing ABA biosynthesis and signaling

Transcriptional regulation plays a key role in the control of seed dormancy,and many transcription factors(TFs)have been documented.However,the mechanisms underlying the interactions between different TFs within a transcriptional complex regulating seed dormancy remain largely unknown.Here,we showed that TF PHYTOCHROME-INTERACTING FACTOR4(PIF4)physically interacted with the abscisic acid(ABA)signaling responsive TF ABSCISIC ACID INSENSITIVE4(ABI4)to act as a transcriptional complex to promote ABA biosynthesis and signaling,finally deepening primary seed dormancy.Both pif4 and abi4 single mutants exhibited a decreased primary seed dormancy phenotype,with a synergistic effect in the pif4/abi4 double mutant.PIF4 binds to ABI4 to form a heterodimer,and ABI4 stabilizes PIF4 at the protein level,whereas PIF4 does not affect the protein stabilization of ABI4.Subsequently,both TFs independently and synergistically promoted the expression of ABI4 and NCED6,a key gene for ABA anabolism.The genetic evidence is also consistent with the phenotypic,physiological and biochemical analysis results.Altogether,this study revealed a transcriptional regulatory cascade in which the PIF4–ABI4 transcriptional activator complex synergistically enhanced seed dormancy by facilitating ABA biosynthesis and signaling.

Methods for Breaking Dormancy of Seeds of Tropical Forage Legumes

The aim of this study was to evaluate methods for breaking dormancy of seeds Neonotonia wightii (perennial soybean), Macrotiloma axilare (archer), Pueraria phaseoloides (tropical kudzu), Calopogonium mucunoides (calopo), which were subjected to the following treatments for physical breaks and physiological dormancy: 1) control;2) scarification with sandpaper;3) immersion in H2SO4 98% for five minutes and subsequent washing in water;4) preheating at 60°C for 150 minutes in an air circulating oven;5) 0.2% KNO3;and 6) gibberellic acid (GA3 0.5%). The results showed that using H2SO4 to break seed dormancy archer and perennial soybean and calopo scarification with sandpaper were the most recommended treatments. Tropical Kudzu presented physiological response to treatments with the use of gibberellic acid and physical treatment using immersion H2SO4. Thus, it is necessary to use techniques to make the breaking dormancy of seeds of legumes, resulting in an increase in the rate of seed germination and rapid deployment of the legume.