Function Of DEK1 In The Regulation Of Vegetative Phase Change And Its Conservative Analysis In Horticultural Crops

The life cycle of a plant is generally composed of the embryonic,juvenile,vegetative and reproductive stages.Among them,the transition from juvenile to adult is also defined as the vegetative phase change,which is a pivotal developmental process of plant's life cycle.Previous studies have shown that miR156-SPL-miR172 pathway is the master regulatory pathway to regulate vegetative phase change in plants.To explore how miR156 itself is regulated,we did an Ethyl methanesulfonate(EMS)mutagenesis for p MIR156A::GUS plants,and a forward genetic screen was performed in the M2 population.Herein,an enhancer,pvt1(promoting vegetative transition 1),with early abaxial trichomes was yielded.Furthermore,we cloned this gene and studied its function in the regulation of vegetative phase change.Some original results have been acquired,as follow:1.The pvt1 has earlier abaxial trichomes on leaf 4.0 with lighter GUS staining and lower GUS expression than p MIR156A::GUS plants under short-day condition.2.Map-based cloning combined with whole-genome sequencing results showed that the mutant resembled dek1(defective kernel1)mutants,which encode a CALPAIN.Sequencing of the DEK1coding region showed that there was a substitution of a G by an A at the 5360-bp position in the CDS of DEK1,resulting in the replacement of a glycine by a glutamic acid in the Cys Pc function domain.3.The dek1 mutant exhibited earlier abaxial trichomes and flowering time,lower leaf emergence rate,and fewer rosettes leaves than Col-0,suggesting that the loss-of-function of DEK1 resulted in accelerated developmental transitions.4.The q RT-PCR results indicated that miR156 and its primary genes,including pri-MIR156A and pri-MIR156C were downregulated in dek1 compared with Col-0,whereas SPL9,pri-MIR172B,miR172,SOC1,AP1 and FT were significantly increased in dek1 plants.Moreover,the expression of DEK1 was reduced with age.5.GA₃-treated assay showed that GA accelerated the production of abaxial trichomes in both Col-0 and dek1 plants,indicating that GA and DEK1 regulated vegetative phase change by parallel pathway.6.Physiological assays showed that the contents of soluble sugar and total soluble protein were siganificantly elevated in dek1 plants compared with Col-0,whereas the content of anthocyanin was deduced in dek1 plants.In addition,the content of soluble sugar was lower in 35S::MIR156A plants and higher in 35S::MIM156 plant than that in Col-0.7.Phylogenetic analysis showed that DEK1 shared the highest similarity with other DEK1proteins in horticultural crops,including VIT?06S0004G00420 in Vitis vinifera?XP?025884542 in Solanum lycopersicum?LOC101213361 in Cucumis sativus and LOC103871041 in Brassica rapa,implying that this study possibly provided a new reference for the horticultural researches.Based on above results,we concluded that DEK1 affected the level of miR156 by regulating the transcripts of MIR156A/C,and further mediated the vegetative phase change.This study provides a theoretical basis for searching the upstream of miR156,and provides valuable information for crop improvement.