The image of the vine, and the closely associated term vineyard, were commonly used throughout the Mediterranean world. Most significant for our passage is the frequent use of vineyards/vine/branches in the Old Testament and in Judaism to symbolize God and Israelites i.e. The People of God. Furthermore, even the notion of a true vine shows up in the Old Testament: "I planted you as a fruitful vine, entirely true. How have you become a wild vine, turned to bitterness" (Jer. 2:21). Here, as also in Isaiah's Song of the Vineyard (Isa. 5:1-7], God, the Gardener, cared for His vineyard but got sour grapes. Consequently he will destroy the vineyard.
Therefore, when Jesus refers to himself as the true vine (John 15:1) He is once again taking an image for Israel and applying it to Himself. Jesus Himself is the true Israel. Given this strong association of the vine with Israel, when Jesus refers to Himself as the vine that is true He signals a contrast between Himself and the official Judaism as represented in the Jewish leaders who have rejected Him and thus cut themselves off from Him and His Father. The role of the Father as the gardener (John 15:1) continues the theme of Jesus' dependence on and subordination to the Father (cf. John 14:28) and also emphasizes again the contrast between Jesus' relationship with God and that of His opponents. The specific focus, however, is on the branches, who are in intimate contact with Jesus (John 15:2). The new community has been established and now must bear fruit for God, in contrast to Israel and its fruitlessness. As among the people of Israel, so among Jesus' disciples, there are those who bear fruit and those who do not (John 15:2).
What is this fruit we should bear? Some scholars suggest Jesus is referring to the fruit that comes from bearing witness to Jesus, that is, converts, the fruit of evangelism or displaying ethical values. Jesus says when they bear much fruit they demonstrate that they are His disciples (John 15:8), and elsewhere He states love as the evidence that one is a disciple (John 13:35; 14:21, 23) and is in union with God and with one another (John 17:21-23). Thus, the image of fruit symbolizes that which is at the heart of both Christian witness and ethics--union with God through Jesus’ Incarnation, Reconciliation, Atonement and Redemption.