| ’Daqing’ grape is an excellent native fresh grape variety in Ningxia with excellent fruit quality,but its poor bud differentiation in facility cultivation is significant and has become a prominent problem limiting the development of the ’Daqing’ grape.To address this issue,this study was conducted in two cultivation modes:solar greenhouse and open field,using paraffin sectioning to observe the process of bud differentiation,determination and analysis of endogenous hormones,nutrient content and mineral elements in the basal 2-3 nodes of winter buds,and transcriptome sequencing analysis in open field cultivation,The results showed that:(1)Significant differences in bud differentiation in ’Daqing’ grape between two cultivation patterns.Under the two cultivation modes,the flowering capacity of ’Daqing’ grape 2-3 nodes was higher than that of 4-5 nodes.In addition,under the open field cultivation conditions,the winter buds at the 2-3 nodes of ’Daqing’ grape had good flowering ability,and their flower bud differentiation time was concentrated,with good sequence and regularity,and finally formed a high proportion of good quality flower buds(53.26%).However,under the solar greenhouse cultivation conditions,the flowering ratio of ’Daqing’ grape was poor(5.98%),the flower bud differentiation process was slow,and the duration of each differentiation stage was long.(2)The endogenous hormone content and ratio of ’Daqing’ grape differed significantly between the two cultivation modes of solar greenhouse and open field.The GA3 content of openfield cultivation(1.49 μg/g)was significantly higher than that of solar greenhouse cultivation(0.33μg/g)in the undifferentiated stage,and the lower GA3 content and lack of change in the undifferentiated stage may be one of the reasons limiting the formation of inflorescences in solar greenhouse.Compared with open field cultivation,the ABA content of ’Daqing’ grape new shoots decreased before the top differentiation stage,and the IAA content of new shoots increased from the hemispheric stage to the primitive differentiation stage,which was an important reason why the winter buds of ’Daqing’ grape cultivated in solar greenhouse could not form good flower buds.Antihormonal balance interacts to regulate flower bud differentiation of grapes.The balanced interaction of hormones regulates the flower bud differentiation of grapes,and the low GA3/IAA ratio(37.11)limits the flower bud differentiation process of solar greenhouse cultivation ’Daqing’grape in the hemispheric stage and the top differentiation stage,while maintaining a stable high ratio of ABA/GA3(0.88)in the inflorescence development stage is conducive to ’Daqing’ grape flowering.(3)The level of soluble sugar and starch in the branches was closely related to the flowering of grapes in solar greenhouse.The drastic decrease in soluble sugar and starch content during the fruit setting stage is one of the reasons that limits the formation of flower buds in solar greenhouse.In open field cultivation with good flowering,it was found that the high soluble protein content(4.16%)was one of the limiting factors for the flowering of ’Daqing’ grape in solar greenhouse.(4)The low C/N ratio(7.23)before the fruit expansion period(hemispheric peak)was the main factor limiting the flowering of ’Daqing’ grape in the solar greenhouse,and the higher-level N and lower levels of P and K content inhibit the flowering of the ’Daqing’ grape in the solar greenhouse during the whole flower bud differentiation process.(5)Transcriptome analysis under open field cultivation conditions showed that a total of 859,3814,4377 and 5464 DEGs were found in the differentiation stages of GP2,GP3,GP4 and GP5 compared with GP1,of which 428 were co-expressed genes.GO analysis showed that DEGs were involved in plant metabolism,enzyme activity,and cellular composition.Through the KEGG enrichment analysis of DEGs,it was found that DEGs were mainly enriched in plants in the biosynthesis of phenylpropane compounds,the signaling of plant hormones,the MAPK signaling of plants,the biorhythm-physiological rhythm of plants,and the metabolic pathways of starchsucrose of plants.(6)The number of transcription factor family genes in different treatments varied significantly,and the bHLH family genes had the highest correlation with other genes,which participated in grape flower bud differentiation,which provided a basis for further study of candidate genes in flower bud differentiation mechanism.In summary,poor flowering in solar greenhouse,low levels of GA3,soluble sugar,C/N ratio,P,K content and high IAA content,soluble protein and N content of in the stage of fruit expansion(hemispheric differentiation stage)were the main factors limiting the flowering transformation of’Daqing’ grape in solar greenhouse.Under the open field cultivation mode,the number of DEGs in the late stage of winter bud differentiation of ’Daqing’ grape was large,and the transcription factor bHLH family genes were the most related to other genes. |
