| Cotton is one of China’s dominant industries and its supply ranks the first in the world steadily in the past few years.With population increasing and arable land decreasing,the cost of planting keeps rising and the conflicts between cotton and cereals become more and more severe.Cultivating short-growthperiod cotton having good quality as well as high yield is crucial for optimizing the agricultural system and ensuring food security.There are some reports indicating that flowering time is relative to wholegrowth period positively,so studying the genes in flowering regulation and declaring its mechanism will help germplasm resource innovation a lot.FLOWERING PROMOTING FACTOR 1 was firstly cloned in mustard and the homologous gene in Arabidopsis thaliana AtFPF1 was then cloned and studied.Over expressing the gene would promote flowering via GA pathway whether in long daylight or in short daylight.Many studies identified that FPF1 had effects on flowering in Artemisia annua,Hordeum vulgare,Triticum aestivum,chrysanthemum,Brassica oleracea L.and Brassica napus L..The homologous gene Oryza sativa Root Architecture Associated 1(OsRAA1)in rice influences not the heading time but root development.We cloned a member of flowering promoting factors GhFLP5 in upland cotton and analysed its expression patterns and functions.The results were as below:1.According to the GhFLP5 sequence on NCBI,primers were designed and a 300 bp fragment was cloned from CCRI50.The protein sequence was analysed and multiple sequence alignment with flowering promoting factors of other species showed that there were three pretty conserved sections from amino terminal to carboxy terminal although GhFLP5 did’t own a domain which was characterized with a specific function.The phylogenetic tree suggested that GhFLP5 has a close relationship to those of Glycine max,Medicago truncatula and Polulus trichocarpa.2.Spatial expression patterns showed that GhFLP5 expressed predominantly in leaves.And it was transcribed at a higher level in early maturity variety CCRI50 than in later maturity variety Lu28.Temporal expression patterns showed that it hit a peak at three-true-leaf stage in CCRI50 but at four-trueleaf stage in Lu28.In different growth-period plants,GhFLP5 expressed the same at temporal patterns and varied in spatial patterns.3.Promoter region was analysed for cis-elements predictions.There were mainly two kinds of elements upstream the start codon.One was light-response elements and circadian elements,and the other was stress-response elements.4.On the basis of elements analyses,salicylic acid(SA),abscisic acid(ABA)and jasmonic acid(JA)were selected to spray the leaves in two-true-leaf stage.After 0 h,2 h,4 h,8 h,12 h and 24 h of the treatment,samples were collected to study the expreesion of GhFLP5.GhFLP5 can be upregulated in response to SA and ABA and downregulated to JA.5.The Arabidopsis thaliana lines over-expressing GhFLP5 bolted about 9 days earlier and flowered about 7 days earlier than the wild type and the rossette leaves decreased to a siginificant level.qRT-PCR showed that flowering promoting genes such as LEAFY(AtLFY)、SUPPRESSOR OF OVEREXPRESSION OF CONSTANS(AtSOC1)、FLOWERING LOCUS T(AtFT)、APETALA1(AtAP1)and FRUITFULL(AtFUL)in the transgenic lines were upregulated obviously and FLOWERING LOCUS C(AtFLC),a gene suppressed flowering was downregulated remarkably.Moreover,the auxin-responsive genes SMALL AUXIN UPREGULATED 20(AtSAUR20)and SMALL AUXIN UPREGULATED 22(AtSAUR22)were induced in transgenic Arabidopsis lines.GIBBERELLIN 20-OXIDASE 1(AtGA20OX1),a gene involved in gibberellin(GA)biosynthesis,was also up-regulated more than two folds.These results indicated that GhFLP5 may play dual roles in the transition to flowering via both GA and IAA signaling pathways. |
