Genetic profile of South Africa's US-VIT 8-7 Vitis hybrid revealed

2019-07-04 12:11
(Netwerk24)

(Netwerk24)

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Introduction:

Jacquez and its berry colour mutant clone, Herbemont, were imported into the Cape Colony (now South Africa) in 1892 to be used as rootstocks to counter the Phylloxera attacks on grapevine roots.

Until recently, Jacquez was thought to be a natural crossing of V. aestivalis x V. cinerea x V. vinifera.  This assumption originated from ampelographic descriptions of the Jacquez by some prominent French viticultural scientists such as Pierre Galet. 

The Jacquez legacy:

For over 200 years most viticultural scientists were of the opinion that the principal wild American seed parent of Jacquez (and Herbemont) was an unknown wild V. aestivalis Michx. species (a.k.a. the summer grape).

However, using microsatellite DNA fingerprinting techniques, an international team of scientists from the USA, France and Hungary have determined that the elusive American wild grapevine parent of Jacquez is V. berlandieri (Planch.) and not V. aestivalis Michx.

The V. berlandieri (Planch.) species is also known as V. cinerea (Engelm.) var. helleri.

It is very likely that some confusion (with V. aestivalis) might have arisen in the past as the result of another "synonym" which has been used to designate V. cinerea, namely, V. aestivalis var. cinerea (Engelm.).

The Vitis berlandieri connection:

The recent publication (Riaz, S. et al.) referred to above, is titled: "Genetic diversity and parentage analysis of grape rootstocks" and was published in the journal of Theoretical and Applied Genetics (March 2019).

Their publication confirms my theory which I published on ResearchGate in 2018. The title of my paper is: "A view into the grapevine history of Jacquez and its connection to the Madeira Islands – Vitis vinifera cv. Cabernet franc is a possible parent of Jacquez".

It was the introduction into France of V. berlandieri as a breeding partner in the late 19th century that led to the development of lime-tolerant rootstocks that were needed to reconstitute/replant their vineyards.

In 1887 the French government imported cuttings of the native V. berlandieri after T.V. Munson (Texas, USA) had recommended that they should use them in their crossings with the riparia and rupestris as part of their rootstock-breeding program.

In 1888, Munson was the second American, after Thomas Edison, to be named a Chevalier du Mérite Agricole of the French Legion of Honour by the French government.

This was in recognition of his work on rootstock development and for his important contribution in saving the French viticultural industry.

The Vitis vinifera content of Jacquez:

Finally, we now have confirmation of the V. vinifera content of the Jacquez hybrid grape cultivar as reported by Riaz et al.,  which is given as follows (percentages):

V. vinifera: 69%

V. berlandieri: 21%

V. rupestris: 7%

V. riparia: 3%

Enter US-VIT 8-7 ... Jacquez x 99 Richter (99R):

The South African rootstock breeding program was initiated under the leadership of Professor Chris Orffer of the University of Stellenbosch (US) in 1949 (exactly 70 years ago).

Many of his rootstock hybrids (US crossings of Jacquez x 99R) were included in field trials from 1974 onwards. The most successful local rootstock crossing has been the US-VIT 8-7.

Now, because 99R is a V. berlandieri var. Rességuier 2 x V. rupestris var. du Lot crossing, and since we now know the genetic content of the Jacquez, it is a relatively simple task to determine the genetic profile of the US 8-7 rootstock.

The following approximate percentages have been calculated:

V. vinifera: 35%

V. berlandieri: 35%

V. rupestris: 30%

Conclusion:

The success of the US-VIT 8-7 as a preferred modern rootstock can be attributed to its well-balanced genetic content (vinifera-berlandieri-rupestris) as highlighted below:


V. vinifera - enables easy rooting of cuttings; improves compatibility between graft and scion.

V. berlandieri - shows some resistance to rootknot nematode; is tolerant to the deadly Pierce's Disease (PD); improves tolerance in lime-rich soils.

V. rupestris - roots easily from cuttings; shows good resistance against the Phylloxera.  

The US 8-7 rootstock has strong vigour, can be cultivated in a wide variety of soil types and features among the 8 most popular South African rootstock cultivars, including: 99R, 110R, Ramsey, 101-14 Mgt, 140 Ruggeri, 1103 Paulsen and SO4.

Dr Jerry Rodrigues (PhD Biochemistry, UCT)

4 July 2019

 

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