The RAV transcription factor TEMPRANILLO1 involved in ethylene‐mediated delay of chrysanthemum flowering

Abstract

SUMMARYTEMPRANILLO1 (TEM1) is a transcription factor belonging to related to ABI3 and VP1 family, which is also known as ethylene response DNA‐binding factor 1 and functions as a repressor of flowering in Arabidopsis. Here, a putative homolog of AtTEM1 was isolated and characterized from chrysanthemum, designated as CmTEM1. Exogenous application of ethephon leads to an upregulation in the expression of CmTEM1. Knockdown of CmTEM1 promotes floral initiation, while overexpression of CmTEM1 retards floral transition. Further phenotypic observations suggested that CmTEM1 involves in the ethylene‐mediated inhibition of flowering. Transcriptomic analysis established that expression of the flowering integrator CmAFL1, a member of the APETALA1/FRUITFULL subfamily, was downregulated significantly in CmTEM1‐overexpressing transgenic plants compared with wild‐type plants but was verified to be upregulated in amiR‐CmTEM1 lines by quantitative RT‐PCR. In addition, CmTEM1 is capable of binding to the promoter of the CmAFL1 gene to inhibit its transcription. Moreover, the genetic evidence supported the notion that CmTEM1 partially inhibits floral transition by targeting CmAFL1. In conclusion, these findings demonstrate that CmTEM1 acts as a regulator of ethylene‐mediated delayed flowering in chrysanthemum, partly through its interaction with CmAFL1.

SmRAV1, an AP2 and B3 Transcription Factor, Positively Regulates Eggplant’s Response to Salt Stress

“…Transcription factors are proteins that help to turn specific genes “on” or “off” by binding to nearby DNA [ 45 , 46 , 47 , 48 , 49 ]. Accumulating evidence has revealed the various functions of RAV transcription factors in the processes of seed germination [ 17 , 21 , 29 ], seedling growth and development [ 16 , 17 , 18 , 50 ], flowering [ 11 , 19 ], and abiotic and biotic stresses [ 22 , 23 , 24 , 29 , 34 , 51 ]—salt stress in particular [ 26 , 27 , 28 , 30 , 50 ]. Among the multiple abiotic stresses, salt stress is one of the most important factors threating plants during their entire growth processes.…”

“…Transcription factors play vital roles in plant growth and plant responses to abiotic stresses [ 9 , 10 ]. The RAV transcription factors contain a B3 DNA-binding domain and/or an APETALA2 (AP2) DNA-binding domain [ 11 , 12 , 13 ]. RAV transcription factors regulate the transcript expression of downstream target genes by binding to core sequences of 5′-CAACA-3′ and 5′-CACCTG-3′ [ 14 ] and function in regulating vegetative growth [ 15 , 16 , 17 ], flowering [ 11 , 18 , 19 ], phytohormone signal transduction [ 20 , 21 ], biotic stresses response [ 22 , 23 , 24 , 25 ], and abiotic stresses response such as salt [ 21 , 26 , 27 , 28 ], and drought [ 21 , 29 ].…”

“…The RAV transcription factors contain a B3 DNA-binding domain and/or an APETALA2 (AP2) DNA-binding domain [ 11 , 12 , 13 ]. RAV transcription factors regulate the transcript expression of downstream target genes by binding to core sequences of 5′-CAACA-3′ and 5′-CACCTG-3′ [ 14 ] and function in regulating vegetative growth [ 15 , 16 , 17 ], flowering [ 11 , 18 , 19 ], phytohormone signal transduction [ 20 , 21 ], biotic stresses response [ 22 , 23 , 24 , 25 ], and abiotic stresses response such as salt [ 21 , 26 , 27 , 28 ], and drought [ 21 , 29 ]. To date, RAV gene family members have been identified in multiple plant species, such as six RAV genes in Arabidopsis thaliana [ 13 ], 26 in wheat [ 30 ], 33 in Gossypium hirsutum [ 31 ], 11 in pear [ 32 ], 15 in rice [ 33 ], 13 in soybean [ 34 ], and five in peach [ 35 ].…”

“…The overexpression of Arabidopsis RAVs ( RAV1 , RAV1L , RAV2 ) decreased the tolerance of Arabidopsis plants to drought and salt stresses in an ABA-independent manner [ 21 ]. The CmTEM1 overexpression delayed chrysanthemum flowering by directly binding to the flowering integrator CmAFL1 promoter, thus repressing this gene’s expression [ 11 ]. In addition, RAV transcription factors also played an important role against pathogenic microorganism attacks in plants.…”

Genome-Wide Analysis of the Related to ABI3/VP1 Family Genes in Chrysanthemum seticuspe Reveals Their Response Patterns to Exogenous Ethylene Treatment

“…For instance, the RAV family genes ETHYLENE RESPONSE DNA BIND-ING FACTOR1 to 4 (EDF1-EDF4) in Arabidopsis are involved in ethylene-mediated petal abscission [30], and the AtEDF1/2/4 genes, which act downstream of the embryonic leaf identity gene FUSCA3, participate in ethylene-mediated developmental transitions [37]. In addition, recent findings have revealed that the chrysanthemum RAV family transcription factor CmTEM1 takes part in the ethylene-mediated floral repression by targeting the APETALA1/FRUITFULL-like1 (CmAFL1) gene directly [38]. Although all of the above studies revealed that RAV genes are involved in ethylene-mediated growth and developmental processes, whether they are involved in ethylene-mediated stress responses needs to be followed up.…”