Research update: The quest for new Pinotage clones

by | Jul 1, 2024 | Technical, Viticulture research

South Africa Wine research projects

P04000060 and P04000060-2019: Evaluation of induced mutation methods to increase the genetic variability of Pinotage and testing Pinotage mutation plants.

P04000060-2024: Analysing induced diversity in a collection of Pinotage plants after gamma irradiance.

Project leaders

Melané Vivier and Phyllis Burger.


Pinotage was developed in South Africa in 1924/1925 and planted commercially since the 1950s. Few commercial clones of Pinotage are available for planting, and their viticultural and oenological properties are quite similar. Given the importance of Pinotage for South Africa, the existence of only a few commercial clones is a limitation. The potential for a more diverse set of clones is desirable and crucial for this cultivar’s continued success and growth.


How clones occur

The occurrence of naturally varying traits within a cultivar is rooted in environmental influences, particularly light quantity and quality, which could induce somatic mutations over time. This process leads to noticeable differences from the original vine, such as yield, vine architecture, phenological progression, etc. These variations can also be reflected in the wine, affecting factors like phenolic content, sugar-acid ratios, aroma components, etc. When these mutations lead to pronounced differences, such as changes in berry colour and/or leaf shapes, the plant material is usually considered a new cultivar. More subtle variations in traits, for example, looser clusters or earlier/later ripening, would lead to potential new clones.

Clones and sometimes new cultivars typically arise in especially very old cultivars widely grown under diverse conditions. Well-known examples are the Pinot group (mutations for berry colour and leaf hairiness) and the Chasselas group (mutations for leaf shape, berry colour and aroma compounds).

Clonal selection programmes are typically employed to enhance a cultivar’s diversity by identifying and testing unique characteristics that offer subtle and desired diversity. Given the predominance of relatively few Vitis vinifera cultivars grown globally, clonal selection has been central to plant improvement strategies for wine grapes for years.

Gamma irradiance can enhance the rate of somaclonal mutations and the likelihood of observing potentially valuable changes that could enrich the cultivar in the form of unique clones. This technique has been widely used to generate variation in various plant species.


The Pinotage Diversity Project

A project was initiated under the leadership of Phyllis Burger (ARC Infruitec-Nietvoorbij) and Prof Melané Vivier (SAGWRI – South African Grape and Wine Research Institute) to attempt to enhance clonal diversity in Pinotage by accelerating mutations that typically lead to clonal diversity. The first phase of this multiphase project, conducted from 2017 to 2018, was dedicated to optimising the methodology to create mutations in three existing Pinotage clones. This established a gamma-irradiated Pinotage collection of approximately 1 500 plants with potential mutations.

The second phase of the project lasted from 2019 to 2023. This phase involved characterising the collection of plants that originated from irradiation and comparing them to the three original Pinotage clones. A subset of the plants was chosen to establish in a field trial of 500 plants, including controls. The collection was successfully planted in 2021 and evaluated over two seasons already. The residual plants were also planted in the field in 2022 for further analysis. The results from this phase of the project were presented to the Pinotage Association, requesting their input in the selection of desired traits in clones going forward.

The third phase, which started in 2024, aims to build on the previous work and conduct viticultural and oenological analyses on chosen subsets of the vines to identify potential material for new clonal selection of Pinotage. An overview of the project phases and the evaluations that form part of each of the stages are outlined in Figure 1.


Pinotage 1

FIGURE 1. An overview of the Pinotage Diversity Project and a timeline of completed, current and future stages of the project.


Results of the project so far

The study’s main findings were as follows:

  • In general, a tendency for a decreased rate of phenological development of irradiated grapevines compared to non-irradiated vines was observed in the early stages of the season, although there were differences between clones.
  • The ripening period of the grapes was significantly altered, with some individuals showing earlier and later ripening periods than the commercially available clones.
  • The population showed many phenotypic differences. The first bunch and berry characteristics observed point to an interesting mix of potentially valuable phenotypes, particularly regarding bunch architecture (looser bunches), bunch and berry sizes, as well as berry skin and flesh colours (Figures 2 and 3) and the overall growth and fruitfulness of the plants.
  • Overall, increased variation was observed in most parameters analysed in the irradiated populations.
  • The data obtained corroborate existing literature that indicates that gamma irradiance can be an effective mechanism to induce mutations in plants.


The phenotypic differences observed included:

  • Very large or very small canopies.
  • Very bushy or very upright growth habits.
  • Loose to very compact berry clusters.
  • Differences in berry size and shape.
  • Differences in skin and flesh colour.
  • Differences in seed number and appearance.


Pinotage 2

FIGURE 2. An example of differences in berry size observed.


Pinotage 3

FIGURE 3. Diversity of bunch architectures, skin and flesh colours, and pit characteristics observed in the population.


In the irradiated population, individuals showed significant changes to the normal skin and flesh colour, particularly the emergence of fruit with highly pigmented flesh. This could be due to a higher anthocyanin accumulation in the flesh, like that of teinturier grapes.

These promising results motivate a more in-depth analysis of the detailed phenology for the population, a time-course analysis of the grapes’ ripening progression, and a chemical analysis of the berry ripening indicators. All these aspects form part of the project’s next phase, which is geared at evaluating the population to identify candidate individuals who can be further selected for more in-depth analyses after being grafted and propagated for further study on the plant and wine level (Figure 1).


Significance of the project

More options regarding Pinotage clonal diversity are essential for the South African wine industry since the cultivar has originated in South Africa and is widely planted. Although Pinotage already has fantastic attributes that need to be ‘kept’ in new clones, clonal material with a slightly different phenological progression, and specifically ripening progression, favourable wine pH, acid balance, as well as phenolic maturity (to name only a few), could provide valuable options to producers and winemakers in terms of Pinotage production and wine styles. The project’s outcomes would be new plant material, either in the form of novel Pinotage clones, potentially new cultivars (for example, a white Pinotage), or breeding lines with novel characteristics that can be used in the ongoing traditional breeding programme. All of these outputs will directly benefit the wine industry.

The South African Pinotage Association supports the project in principle and financially. In addition, they provide all the wines needed to compare the chemical and sensory descriptions of the current Pinotage clones against the new material. The project also supports several postgraduate students participating in the research as part of their research activities towards their degrees.


For more information, contact Melané Vivier at


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