Functional Assignment Of A Photoperiod Sensitive Gene ZmCOL3 In Maize

Photoperiod-sensitivity is an important factor in regulation of florescence in maize,the existence of photoperiod-sensitivity limits severely the use of tropical and sub-tropical maize germplasm in temperate regions.Understanding the mechanism of maize flowering regulation,and exploring photoperiod-sensitive genes,provide likely a theoretical basis for genetic improvement to maize.In our previous genome-wide association study,we found that one of the photoperiod-sensitive genes,i.e.ZmCOL3(C2C2-CO-like-transcription factor 3),was tightly to maize flowering stage.However,it is still unknown whether ZmCOL3 functions in regulation of maize flowering stage.Therefore,we performed the following studies and the results obtained:1.The maize inbred line B73 was used to isolate ZmCOL3 gene from the genome.Sequence analysis of ZmCOL3 revealed that its full-length DNA is 1545 bp constituting two transcripts: ZmCOL3 T01 and ZmCOL3 T02.Respectively,a B-box-type zinc finger and a CCT(CO,CO-LIKE and TIMING OF CAB1)domain.2.We constructed ZmCOL3 expression vector fussed with the green fluorescent protein gene,gfp,and transformed it into maize protoplasts.Observation by laser confocal microscopy proved that.ZmCOL3 appeared to localize inside nucleus.This result is consistent with bioinformatics study.3.We constructed ZmCOL3-overexpression vector and the RNAi vector and transformed them respectively into maize using agrobacterium-mediated maize technology.The transgenic plants were verified by PCR,qRT-PCR and phenotypic chacterization in field under long and short daylight.The results showed that: the ZmCOL3-overexpressed maize exhibited a 2-3 days postponed development of corn tassel,pollen and silk in long-day and short-day.In addition,overexpression of ZmCOL3 in long and short days increased plant height,ear height,number of stem nodes and total leaf number in the transgene maize.Taking the above results together,it may conclude that ZmCOL3 functions likely in regulation of flowering period of maize in a multifunctioning pattern,such that the gene affects not only the flowering period,but also the plant height,the ear height,the stem node number and the total leaf number.Current observation of ZmCOL3 provides preliminary information for possible genetic improvement of maize.