On 4 May 2016 I reported in MyNews24 that 'Cabernet franc' was tentatively shown to be a parent of 'Jacquez', while the wild parent (an American Vitis aestivalis) still remained unknown.
The Vitis vinifera background of 'Jacquez' (formerly known as Lenoir or Black Spanish) was investigated by using Microsatellite DNA (Simple Sequence Repeat or SSR) analysis.
The original Jacquez cultivar was likely the result of a random natural hybridization event that took place between two grapevine species followed by successful selection in the field and is postulated to have occurred either in Georgia or South Carolina in colonial America at some point in the late 18th century. Later on, Jacquez became one of the first 'natural' direct-producers (grape-bearing varieties) to have been used on European soil and, as a rootstock, became a valuable cultivar that helped to save the European viticultural industry from total destruction by the phylloxera root-sucking aphid.
The phylloxera aphid was unwittingly introduced into France in 1863 carried on some phylloxera-infected roots of imported American Concord grapevines. It is significance to mention that the phylloxera scourge only arrived on the island of Madeira approximately 10 years later than in France, in 1872. As a result, Madeira also began employing the Jacquez grapevine, which was already being used there as a direct-producer, but had now found a new purpose, as a rootstock.
In 1859, that is, before the phylloxera outbreak, a consignment of Jacquez cuttings was 'exported' from America to Europe to help in the fight against powdery mildew (oïdium fungus). However, approximately 10 years later during the phylloxera infestation in Europe, the French vineyard farmers were in need of a new supply of the same Jacquez variety that had been previously imported from America, because that cultivar was found to be thriving as opposed to the vinifera vines which were dying off. However, it was reported in the Bushberg Catalogue of American Grape Vines of 1883 that the cultivation of the Jacquez variety had been totally abandoned and that there were none left.
However, an alternative 'Jacquez' cultivar, which was known in America as Black Spanish or Lenoir, was supplied to the French authorities instead. This variety of 'Jacquez' was offered to the French because an ampelographic examination (comparison of leaf shape, berry size, colour etc.) of the cultivar had indicated that it was similar (or even identical) to the original Jacquez cultivar that had previously been sent to France. Soon, France had sufficient 'Jacquez' cuttings available so that it was not necessary to import any longer. In fact, as news of this 'phylloxera- and powdery mildew-resistant' grapevine, Jacquez, spread to the New World, there was a big demand for it and many Jacquez cuttings were now being 'exported' to countries such as North America and South Africa among others.
In 1909 the American ampelographer T. V. Munson tells the story of: “…a small cutting of the Jacquez vine 'travelled' from the Madeira islands to the USA in a cigar box. This cigar box surfaced again in Cincinnati where it was supposed to be received by Mr. Longworth. The cutting was thereafter propagated, leading to the name 'Cigar Box Grape' for Jacquez”.
In retrospect, it is now very easy to imagine the total confusion that must have existed during those early years, when an important grapevine cultivar such as Jacquez assumed many different names. One did not really know whether one had the original cultivar or a more inferior and/or superior clone of that same cultivar.
The important message to be learnt here is that only a DNA analysis can provide definitive answers as to the true identity of those various grapevine cultivars, as will be illustrated in the following short story about Jacquez.
Please read the background to this article in the work that I have previously reported in MyNews24 - article dated 4 May 2016 at the following URL: http://www.news24.com/MyNews24/the-amazing-cabernet-franc-20160504.
However, the single most important revelation resulting from this piece of work is the fact that the SSR analysis has indicated that the original Jacquez cultivar was indeed the cultivar that found its way to the Madeira Islands and can now still be found also in South Africa as well as in a few other locations.
The experiment that I am about to briefly describe was one in which DNA fingerprinting analysis was performed on three 'previously identified' Jacquez cultivars albeit by using ampelography rather than by DNA protocols.
The three Jacquez cultivars have now been tested by having their Microsatellite (SSR) DNA analysed and some results are discussed below:
Sample (1) was a 'South African Jacquez' collected from a private garden in the Western Cape, South Africa.
Sample (2) was a 'Spanish Jacquez' which was the subject of a thesis in Spain (Tébar 2007).
Sample (3) was a 'French Jacquez' which is reported in the public Vitis International Variety Catalogue (VIVC) database (http://www.vivc.de/).
An accession (existing grapevine collection) of the ‘Spanish Jacquez’ is kept in a research facility near Madrid, Spain, whereas the 'French Jacquez' accession is kept at the INRA-Vassal grapevine facility in Montpellier, France.
From the SSR analyses it was discovered that both of the European accessions (i.e. the 'Spanish' and 'French' Jacquez cultivars) were originally derived from the 'oldest' known Jacquez cultivar (which is represented here as the 'South African Jacquez') from seedlings that 'originated' from self-pollinated 'South African Jacquez' individuals. This is an important revelation.
It is now quite obvious that the subsequent 'selection' of those seedlings must have been purposefully carried out by someone in the field somewhere on the East or Southeast coast of colonial America.
A quick lesson on DNA fingerprinting technology:
To illustrate how one can easily arrive at such a conclusion from SSR analysis results, one must first realize that a plant such as a grapevine, will have two 'sets' of DNA in its genome (its full complement of DNA). One 'set' has been inherited from the pollen parent and a second 'set' from the seed parent. The DNA are given code names that are followed by numbers (called alleles) indicating the short lengths of repeating DNA (the so-called SSR) that are given two 'sizes' in base pair lengths separated by a 'colon'. For example, VVMD7 is the abbreviation for the 'marker' called Vitis Vinifera Microsatellite DNA_7, and a particular grapevine might have VVMD7 alleles of 234:236. Note that the '234 base pair DNA' could be inherited from e.g. the mother and the '236 base pair' from the father. What one needs to remember is that the vinifera grapevine is hermaphrodite, meaning that it has both male and female sex organs so that it can self-pollinate (called 'selfing').
Now to the results proper:
One will now appreciate that the 'selfing' of a 'South African Jacquez' cultivar which has the VrZAG79 alleles 249:251 could result in an offspring with the VrZAG79 alleles 249:249 (e.g. found in the 'French Jacquez'), but it would not be possible to obtain the 'South African Jacquez' VrZAG79 alleles 249:251 from the selfing of the ‘French Jacquez’ because there is no 251 base pair allele in the 'French Jacquez' cultivar (in other words, it is not possible the other way around).
Similarly, the 'selfing' of the 'South African Jacquez' which has the VVMD7 alleles 237:239 could result in an offspring with VVMD7 alleles 239:239 (e.g. found in the 'Spanish Jacquez'), but it would not be possible to obtain the VVMD7 alleles 237:239 if the selfing occurred the other way around. In a blunt way one can say that the 'South African Jacquez' cultivar is the parent of both the 'French Jacquez' AND the 'Spanish Jacquez' cultivars BUT the latter two could never be parent to the 'South African Jacquez' cultivar.
So, in conclusion, it is fair to say that there are now accessible and practical DNA analytical methodologies available to farmers and plant breeders that will assist them to select their preferred grapevine cultivars and adapt them to their specific environment.
The story of the Jacquez cultivar has been one great lesson for all of us – that a chance pollination event that took place over 200 years ago did not go unnoticed by some unknown grape farmer and in so doing contributed significantly to saving the world’s grapevine germplasm for future generations.
By Dr. Jerry Rodrigues (PhD Biochemistry)
(1 August 2016)