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Acta Agronomica Sinica ›› 2022, Vol. 48 ›› Issue (4): 812-824.doi: 10.3724/SP.J.1006.2022.14076


Function analysis of GmELF3s in regulating soybean flowering time and circadian rhythm

XU Xin(), QIN Chao(), ZHAO Tao, LIU Bin, LI Hong-Yu*(), LIU Jun*()   

  1. Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, Beijing 100081, China
  • Received:2021-04-25 Accepted:2021-07-12 Online:2022-04-12 Published:2021-08-11
  • Contact: LI Hong-Yu,LIU Jun E-mail:935816885@qq.com;82101181010@caas.cn;lihongyu@caas.cn;liujun02@caas.cn
  • About author:First author contact:**Contributed equally to this work
  • Supported by:
    Agricultural Science and Technology Innovation Program of Chinese Academy of Agricultural Sciences(2060302-2-20);Soybean Grain Storage Technology Program(CAAS-ZDRW202003)


Soybean is a typical short-day crop. Photoperiod sensitivity seriously affects flowering time, yield, and planting range of soybean, but the mechanism underlying photoperiod and circadian rhythm regulation is still unclear. In Arabidopsis thaliana, ELF3, together with ELF4 and LUX, forms the ELF4-ELF3-LUX complex (Evening Complex, EC), which plays an important role in circadian rhythm and flowering time regulation. In this study, soybean mutants of Gmelf3a/j, Gmelf3b-1, and Gmelf3b-2 were obtained by CRISPR/Cas9 gene editing system. We found that GmELF3b-1 regulated the flowering time in soybean under long-day conditions by observing flowering phenotypes in these mutants. The phenotypes of heterozygous double mutants revealed that there was functional redundancy among GmELF3a/J, GmELF3b-1, and GmELF3b-2 in regulating flowering time of soybean. Through detecting the expression of circadian related genes in soybean by using qRT-PCR, it was found that the relative expression patterns of GmCAB, GmPRR9a, and GmPRR7a were changed in soybean. In summary, these results suggested that GmELF3a/J, GmELF3b-1, and GmELF3b-2 may regulate the circadian rhythm and flowering time through GmPRR9a and GmPRR7a in soybean.

Key words: photoperiod, circadian clock, flowering time, Evening Complex, ELF3

Table 1

Primers for the construction of CRISPR/Cas9-ELF3 vectors"

Primer name
Primer sequence (5'-3')

Fig. 1

CRISPR/Cas9 vector diagram and phylogenetic analysis of GmELF3s A: CRISPR/Cas9 vector diagram; B: phylogenetic analysis of soybean GmELF3s with ELF3 in Arabidopsis, snap bean (Phaseolus vulgaris), azuki bean (Vigna angularis), mung bean (Vigna radiate), wheat (Triticum aestivum L.), maize (Zea mays L.), and rice (Oryza sativa L.)."

Fig. 2

Schematic diagram of the targeted sequences in GmELF3a (A), GmELF3b-1 (B), and GmELF3b-2 (C) The blue sequences are the protospacer adjacent motif (PAM) sequences, and the red sequences are the target genome sequences."

Fig. 3

Statistical analysis of flowering time and plant height of Gmelf3s mutants under short-day condition A: phenotype of Gmelf3a-1.1-1, Gmelf3a-1.8-1, Gmelf3a-1.8-2, Gmelf3b1-2.5-1, and Gmelf3b2-3.9-1 mutants under short-day conditions; B: statistical analysis of flowering time of Gmelf3a-1.1-1, Gmelf3a-1.8-1, Gmelf3a-1.8-2, Gmelf3b1-2.5-1, and Gmelf3b2-3.9-1 mutants under short-day conditions; C: statistical analysis of plant height of Gmelf3a-1.1-1, Gmelf3a-1.8-1, Gmelf3a-1.8-2, Gmelf3b1-2.5-1, and Gmelf3b2-3.9-1 mutants under short-day conditions. **: P < 0.01."

Fig. 4

Flowering phenotype of Gmelf3s mutants (A) and flowering time statistics (B) under long-day conditions * and ** represent significant difference at the 0.05 and 0.01 probability levels, respectively."

Fig. 5

Mutation sequences and flowering time of double mutant under short-day condition A-B: the mutation sequence of Gmefl3a, Gmefl3b-1, and Gmefl3b-3 in heterozygous double mutants; (A) the first two sequences are GmELF3a and mutated Gmelf3a, the last two sequences are GmELF3b-1 and mutated Gmefl3b-1; (B) the first two sequences are GmELF3a and mutated Gmelf3a, the last two sequences are GmELF3b-2 and mutated Gmefl3b-2. C-F: statistical analysis the flowering time of heterozygous double mutant; (C) flowering phenotype of Gmefl3a/b1-1-1 double mutant; (D) statistical analysis of flowering times in Gmefl3a/b1-1-1 double mutant; (E) flowering phenotype of Gmefl3a/b2-2-1 double mutant; (F) statistical analysis of flowering times in Gmefl3a/b2-2-1 double mutant. * and ** represents significant difference at the 0.05 and 0.01 probability levels, respectively."

Fig. 6

Circadian rhythm analysis of GmELF3a, GmELF3b-1, and GmELF3b-2 A, B: the relative expression pattern of GmELF3a under long-day and short-day conditions, respectively; C, D: the relative expression pattern of GmELF3b-1 under long-day and short-day conditions, respectively; E, F: the relative expression pattern of GmELF3b-2 under long-day and short-day conditions, respectively."

Fig. S1

Circadian rhythm analysis of GmELF3a, GmELF3b-1, and GmELF3b-2 in Tianlong 1 and Gmelf3s mutants"

Fig. S2

Regulation of circadian clock gene rhythm by GmELF3s on GmTOC1a, GmPRR5, GmELF4, GmLUX1, GmCCA3, and GmREV8a"

Fig. 7

Regulation of GmELF3s on the circadian clock genes of GmCAB, GmPRR9a, and GmPRR7a A: the relative expression levels of GmCAB in Gmelf3a, Gmelf3b-1, and Gmelf3b-2 mutant; B: the relative expression of GmPRR9a in Gmelf3a, Gmelf3b-1, and Gmelf3b-2 mutant; C: the relative expression levels of GmPRR7a in Gmelf3a, Gmelf3b-1, and Gmelf3b-2 mutant."

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