Question: What is the significance of Jesus's action in sharing bread and wine?
About the article "Last Supper", section "Institution of the Eucharist".

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Bread has a significance beyond mere nutrition in many cultures in the West and Near and Middle East because of its history and contemporary importance.
Bread is also significant in Christianity as one of the elements (alongside wine) of the Eucharist; see sacramental bread.
The word "companion" comes from Latin "com-" "with" + "panis" "bread".
The political significance of bread is considerable.
In 19th century Britain, the inflated price of bread due to the Corn Laws caused major political and social divisions, and was central to debates over free trade versus protectionism.
The Assize of Bread and Ale in the 13th century demonstrated the importance of bread in medieval times by setting heavy punishments for short-changing bakers, and bread appeared in the "Magna Carta" a half-century earlier.
Like other foods, choosing the "right" kind of bread is used as a type of social signalling, to let others know, for example, that the person buying expensive bread is financially secure, or the person buying whatever type of bread that the current fashions deem most healthful is a health-conscious consumer.
As a simple, cheap, and adaptable type of food, bread is often used as a synecdoche for food in general in some languages and dialects, such as Greek and Punjabi.
There are many variations on the basic recipe of bread worldwide, including pizza, chapatis, tortillas, bocadillo, baguettes, brioche, pitas, lavash, biscuits, pretzels, naan, bagels, puris, and many others.
There are different types of traditional "cheese breads" in many countries, including Brazil, Colombia, Italy, and Russia. 
As introduced by Latter Day Saint prophet Joseph Smith, Jr., the sacrament included the use of fermented wine, though the Church now uses water in each congregation's weekly sacrament meeting.
Commanded in an 1830 revelation not to purchase alcohol from enemies, The Church of Jesus Christ of Latter-day Saints focused on producing its own wine, eventually owning and operating vineyards and wineries in Utah and California (including Napa Valley) during the 19th century.
In 1833 Joseph Smith received the revelation known as the Word of Wisdom, part of which states that alcohol consumption is harmful to a person's health and well-being.
Initially the Word of Wisdom was treated simply as counsel, and the early saints would still drink alcohol on occasion.
During the late 19th century, church leaders slowly started to take the Word of Wisdom as a commandment.
This increased respect for the Word of Wisdom, combined with the scripture in Doctrine and Covenants 27: "t mattereth not what ye shall eat or what ye shall drink when ye partake of the Sacrament, if it so be that ye do it with an eye single to my glory," led congregations to begin substituting water for the Sacramental wine.
(Water has also been used as a symbol of Christ and his mission at various times, including Jesus's 'living water' sermon.)
The practice was officially adopted church-wide in 1912.
Occasionally circumstances permit various other food substitutes as well.
Crackers and tortillas are sometimes used in outdoor, rugged settings, such as church sponsored Boy Scout camping trips.
The Church's official policy, however, is that Boy Scout troops not camp or hike on Sundays.
Stories abound of WWII impoverished European congregations using potato slices.
In the above situations, however, the word "bread" (in English) is typically used in the prayers. 
The symbolic food of the ancient Israelites continued to be important among Jews after the destruction of the Second Temple in 70 CE or AD and the beginning of the Jewish Diaspora.
Bread, wine, and olive oil were seen as direct links to the three main crops of ancient Israel — wheat, grapes, and olives.
In the Bible, this trio is described as representing the divine response to human needs () and particularly the need for the seasonal rains vital for the successful cultivation of these three crops.
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The significance of wine, bread and oil is indicated by their incorporation into Jewish religious ritual, with the blessings over wine and bread for Sabbath and holiday meals and at religious ceremonies such as weddings, and the lighting of Sabbath and festival lights with olive oil. 
Transubstantiation (in Latin, "transsubstantiatio", in Greek μετουσίωσις metousiosis) is the change whereby, according to Catholic doctrine, the bread and the wine used in the sacrament of the Eucharist become, not merely as by a sign or a figure, but also in reality the body and blood of Christ.
The Catholic Church teaches that the substance or reality of the bread is changed into that of the body of Christ and the substance of the wine into that of his blood, while all that is accessible to the senses (the outward appearances - "species" in Latin) remains unchanged.
What remains unaltered is also referred to as the "accidents" of the bread and wine, but this term is not used in the official definition of the doctrine by the Council of Trent.
The manner in which the change occurs, the Catholic Church teaches, is a mystery: "The signs of bread and wine become, in a way surpassing understanding, the Body and Blood of Christ.
"The Eastern Orthodox Church, Oriental Orthodox Church, and Church of the East have sometimes used the term "transubstantiation" ("metousiosis"); however, terms such as "divine mystery", "trans-elementation" (μεταστοιχείωσις "metastoicheiosis"), "re-ordination" (μεταρρύθμισις "metarrhythmisis"), or simply "change" (μεταβολή) are more common among them and they consider the change from bread and wine to flesh and blood a "Mystery". 
Luke 6 is the sixth chapter of the Gospel of Luke in the New Testament of the Christian Bible.
Jesus's teaching about the Sabbath enrages the religious authorities and deepens their conflict.
The recruitment of Jesus' first disciples is completed and followed by a sermon where key aspects of Jesus's teaching is presented.