An Ode to Chenin Blanc

We are back in our vineyard, our winter hibernation coming to an end, we're coming out of dormancy, reawakening muscles that have been on a long hiatus. Ouch!
I was looking for a reference paper for another blog that I am in the middle of writing and found something written by L. Peter Christensen titled Chenin Blanc, which is part of a book called Wine Grape Varieties in California written by Larry Bettiga.
Just looking at this photo of Chenin Blanc grapes got me inspired for the work ahead in the vineyard this year.
While I knew that Chenin Blanc is the white grape found in the Loire region of France, I did not know that this variety has been growing in Anjou since 845 A.D.
Here is the description of Chenin Blanc from Christensen's paper:

• Clusters: medium to large; long conical, compact, often winged; short to medium peduncles.
• Berries: medium; oval, yellow-green.
• Leaves: medium; 3- to 5-lobed with U-shaped petiolar sinus; inferior lateral sinuses often shallow; short teeth; moderately dense hair on lower leaf surface; leaf veins near the petiolar junction pink-red and noticeable on upper surface.
• Shoot tips: felty white; dense hair on young leaves makes them appear cream-white.
• Clones: FPS 02, 03, and 04 were derived from FPS 01 using heat therapy.
           →FPS 05 was established from a different California vineyard.
           →A comparative trial demonstrated that Chenin blanc FPS 04            was the most productive, followed closely by selection 01.
           →Selection 05 should not be planted because of its higher            bunch rot potential (75 percent increase over FPS Chenin            blanc 01 and 04), which is due to small, very compact            clusters in spite of its smaller berries.
• Harvest: Mid-season variety. In our area, we have been harvesting our Chenin Blanc during the third week in September.
• Grape attributes: Chenin blanc has moderately good acid level, attaining its best balance of sugar and acid in the cool to moderately warm growing regions.

2012 Zenato Ripassa

My husband chose this 2012 Zenato Ripassa to pair with his cassoulet that we shared with our friends this weekend. It was inky purple in color, full bodied with a hint of spice and dried fruit flavors. The wine brought up a discussion regarding how Ripasso is made. My husband knew that it was the passing of the juice over the pressed Amarone grape skins but that still felt a little vague so I did a little searching on the Internet to educate myself.
The first thing to know is that Ripassa is made in the Veneto region located in northeast Italy.¹

Ripasso is a blend of three regional native red grape varieties, Corvina, Rondinella and occasionally, Molinara. This blend is called Valpolicella. Ripasso comes from adding the basic Valpolicella wine into the cask containing the skins and lees left over from recently fermented Amarone wines. The resultant Ripasso has both the freshness and lightness of the Valpolicella, but also has some of the characteristics of Amarone such as flavors of blackberries, dried fruit such as raisins and black currents with a hint of spices.
My husband said this wine was less than $20.00, so I'll put it under my "Wines Under $20" tab.
References:
1. Map of Italian Wines Region is from Better Tasting Wine.
2. RIPASSO WINES - FOR THOSE WHO LOVE BIG REDS BUT CAN’T ALWAYS AFFORD AMARONE

BBC Story About Machiavelli and Wine

My husband is a global internet surfer and sent me this link Machiavelli's secret tunnel to fame that he found on the BBC. The story goes that there is a tavern in San Casciano called L’Albergaccio (translation: the 'bad' inn) that Machiavelli frequented after he was banished from the court of the Medici in 1512.

What is important about this tavern? This is where Machiavelli wrote "The Prince". How did Machiavelli get to the tavern? Through an underground tunnel lined with wine barrels that connected the farmhouse where he lived with the tavern. Now, that is some secret tunnel!

Maybe it's time for me to read "The Prince".

Seven Stages of Shoot Growth

Awhile back, I was doing some digging around to try to answer the question Why Does a Grape Cane Shred Its Bark and came upon many words such as phellogen, phellem and phelloderm, that were not in my ordinary/limited lexicon. During that search, I came upon a really great diagram that merited another look.
Since I did the initial search in 2014, I forgot where I got this diagram from and it took a little directed search on the internet to find the source. Originally, the diagram came from J. C. Fournioux, but I found it in Biology of the Grapevine, on page 51.¹
While we wait for budbreak to come to our neck of southeastern Connecticut, I thought I would revisit the shoot diagram. According to the authors, Mullins et al. shoot growth can be divided into 7 stages. The 7 stages are labeled and the parts of the shoot that forms during those stages are also annotated. I found the diagram to be very helpful to my understanding of shoot growth.

A rapidly growing shoot increases by 3-4 centimeters per day and produces a new leaf (or tendril) every 2 to 3 days. In looking back at some of the photos I took in 2016, grape shoots definitely do grow very quickly.

While my husband and I anxiously wait for budbreak, we're back in the vineyard, as another season begins.
Reference:
1. Michael G. Mullins, ‎Alain Bouquet, ‎Larry E. Williams, Biology of the Grapevine, 1992.

2010 Kir Yiannis Ramnista Xinomavro

Staying on the same Greek wine theme from a few nights ago, my husband brought out this Xinomavro from Kir Yianni. He said that he was saving this wine to share with our Greek friends because they have a son named "Yiannis". Too bad. We broke into it. This wine is already 7 years old. This is a wine made from the Xinomavro grape. The color was very dark purple in the glass and it was dry with rounded tannins. The wine still tasted very youthful to me.

Xinomavro means "acid-black" in Greek and is a grape grown in northern Greece. Ktima Kir Yianni is located in Naoussa, which enjoys Mediterranean climate with continental influences, featuring mild winters and relatively hot summers. The Xinomavro grape is the second most planted red variety in Greece, after the Agiorgitiko grape.

Last Word: Why We Have White Grape Varieties

I wrote a series of science heavy blogs about Why We Have White Grapes: VvmybA1 Gene Silencing, I wanted to write just one more blogpost about the topic. This really boggled my mind!
The first thing to know is that there is a family of transcription factors called Myb. Transcription factors decode the information contained in the nuclear DNA to produce a single strand of messenger RNA. In grapes, Myb-related genes such as VvmybA1 regulate anthocyanin biosynthesis by controlling expression of the gene for UFGT (UDP glucose-flavonoid 3-o-glucosyl transferase).¹

In fact, there are three alternate forms (alleles) of the VvmybA1 gene.

The VvmybA1a allele contains a retrotransposon, Gret1, upstream of the VvmybA1-coding sequences. Mutations caused by retrotransposon insertions in or near genes can alter gene expression or the structure of the encoded proteins.³ Since no VvmybA1 transcript was detected, the Gret1 insertion in VvmybA1a must block expression of the gene. In addition, the lack of berry color was due to homozygousity of the VvmybA1 containing the Gret1 retrotransposon insertion. In contrast, the alleles VvmybA1b and VvmybA1c were found to be functional.
Cocktail Party Conversation: If you ever find yourself at a cocktail party holding a glass of white wine and needing something to talk about, you might say something like this: "I love white wines. Isn't it cool to know that if it wasn't for a mutation in the gene encoding a transcription factor, we might only have had red wines in this world."
References:
1. Azuma, A., Kobayashi, S., Yakushiji, H., Yamada, M., Mitani, N., and Sato, A., "VvmybA1 genotype determines grape skin color", Vitis 46 (3), 154–155 (2007).
2. Yung-Fen Huang, Sandrine Vialet, Jean-Luc Guiraud, Laurent Torregrosa, Yves Bertrand,Veronique Cheynier, Patrice This and Nancy Terrier, A negative MYB regulator of proanthocyanidin accumulation, identified through expression quantitative locus mapping in the grape berry, New Phytologist, (2014) 201: 795–809 doi: 10.1111/nph.12557.
3. Lijavetzky et al., Molecular genetics of berry colour variation in table grape, 2006, Mol. Genet. Genomics, 2006: 427-435.

New Tab: Trellis System

This blog is about my efforts to collate the various blogposts that I've written regarding similar topics. One thing that we found out early on, after we originally planted our 6800 tall grafts is that our vines took off and needed to be supported STAT!

Looking at the photo above reminds me of how far we have come. You can check out the Trellis System Tab, under which you will find the following posts:
Checking Out Black Locust for Fence Posts
Our Vineyard, Next Steps
Endpost Designs
More Things to Do: Trellis Installation
We're Lineposting
Post Progress
Days of Pounding End Posts
End Post Pounding Help in the Vineyard
The End of End Post Pounding
Augering Anchors
How Long Does It Take to Put in Ground Anchors
Anatomy of an Endpost
Installing Our Trellis System
Linepost Pounding Help in the Vineyard
Installing Our Fruiting Wire
Installing Our Trellis System
In the last blogpost, I summarized how long it took to pound in the lineposts, endposts and earth anchors. All in all, it took us from May 2014 to June 2015 to install our trellis system, this is not including stringing our trellis wires.

The lesson that we learned is that for our south vneyard, we will put in all of our trellising material before we plant our vines!

2000 Chateau Yon-Figeac

My husband brought out that 2000 Yon-Figeac recently when our son, daughter-in-law and new baby James came for a visit. Chateau Yon-Figeac is a right bank Bordeaux located in St. Emillon.
I listened to a Youtube video to learn about Chateau Yon-Figeac. They have 25 acres planted with Cabernet Franc, Merlot and as of 2005, Petit Verdot. They produce 80,000 bottles, initially fermented in stainless steel and then aged in oak.
This wine is now 17 years old. The color was dark purple, I didn't discern much fruit notes, and the wine was very dry and it went well with the vegetarian lasagna.

Why We Have White Grapes: VvmybA1 Gene Silencing

At the end of my blogpost Genes Involved in Anthocyanin Synthesis, I let the cat out of the bag:
       the Myb gene called VvmybA1 is likely the gene underlying the mapped        locus controlling berry colour in grapes.¹
Now we are really close to answering the question Why Do We Have White Grape Varieties?
In 2004, Kobayashi and his fellow researchers published a brief report in the journal Science that presented the results of experiments that they did. They took two white cultivars, Italia (It) and Muscat of Alexandria (Al) to create two red cultivars, Ruby Okuyama (Ru) and Flame Muscat (Fl) and looked at the genetic transcripts. Here is what they found:

They looked for the presence of the VvmybA1 gene. The results illustrated that the white cultivars in lanes 1-8 showed no expression of VvmybA1, whereas in lanes 9-15, the red cultivars showed expression of VvmybA1.
These experiments showed that the colour phenotype is due to the combined additive effect of the VvMybA gene and its alleles. They showed that a cluster of three MYB-type transcription factor genes, VvMybA1 and VvMybA2 were functionally involved in berry pigmentation. They also identified a third expressed gene, VvMybA3.
Long awaited for answer to why we have white grapes:
Kobayashi et al. discovered the existence of a retrotransposon insertion upstream of the VvmybA1, which they named Gret1 for grape retrotransposon 1, is responsible for the silencing of the first two functional genes creating the white grape!

References:
1. Kobayashi, S., Goto-Yamamoto, N., and Hirochika, H., Retrotransposon-induced mutations in grape skin color. Science, 304, 982 (2004).

2015 Sigalas Assyrtiko

I'm waiting on a reference paper so I can finish up my odyssey regarding how the world came to get white wines. So, in the meantime, I thought I would blog about this 2015 Sigalas Assyrtiko that we drank a few nights ago.
Drinking this wine brings back some fond memories from 2004 of going to Sigalas located on Santorini. We went there in August and the weather was hot, hot, hot and dry. We came upon Sigalas Winery and stopped to relax, have a glass of wine and a bite of food. We had heard that the grape vines in Santorini were fashioned like a basket on the ground to protect the grapes from the heat and winds that are prevalent on Santorini. Sadly, Sigalas seemed to have given up that type of grape growing, in favor of the more conventional trellising.

The Assyrtiko grape is indigenous to Santorini and is an ancient variety that grows on the volcanic soils of the island. This wine was fruity, but it also had acidity and minerality to balance and round out the flavors. What's more, it brought back some wonderful memories spent in the company of good friends.

Genes Involved in Anthocyanin Synthesis

Have you ever wondered why we have red and white wines? I found a really good research paper that explained this phenomenon almost a year ago and then I fell into a rabbit hole. I needed to explain first, why we have red grapes, and it took me a few blogposts to get there.
In my previous blogpost Why Do We Have White Grape Varieties?, I wrote that white grapes appear to lack anthocyanins because they did not express UFGT (UDP glucose-flavonoid 3-o-glucosyl transferase). Then, I finished the post with a cliff hanger. In 1996, when Boss et al.,¹ did their seminal experiments they didn't really know the underlying genetic reasons why white grapes did not contain anthocyanins in their skins.
Ten years later in 2006, Lijavetzky and fellow collaborators answered the question in their research paper titled Molecular genetics of berry colour variation in table grape.²
The Role of Transcription Factors
To get a handle on what they did, requires some knowledge of transcription factors. The Wikipedia defines a transcription factor as a protein that controls the conversion of genetic information from DNA to messenger RNA, by binding to a specific DNA sequence.(For a really good explanation on transcription factors check out Khan Academy on Transcription Factors.)
Two groups of transcription factors called MYB and bHLH are the main regulatory genes associated with the control of anthocyanin biosynthesis in plants. In 2014, Huang et al. mapped out that phylogenetic tree for the MYB transcription factors involved in the phenylpropanoid pathway.³

In the diagram shown above, the main character implicated in anthocyanin production in the grape berry skin is the gene called VvmybA1 located on chromosome 2.⁴ The details of the investigation into how the gene VvmybA1 is responsible for color will sadly, need to be postponed for another blogpost. Please stay tuned, it's pretty cool.
References:
1. Boss P, Davies C, Robinson S (1996b), "Expression of anthocyanin biosynthesis pathway genes in red and white grapes", Plant Mol Biol, 32:565 - 569.
2. Lijavetzky et al., Molecular genetics of berry colour variation in table grape, 2006, Mol. Genet. Genomics, 2006: 427-435.
3. Yung-Fen Huang, Sandrine Vialet, Jean-Luc Guiraud, Laurent Torregrosa, Yves Bertrand,Veronique Cheynier, Patrice This and Nancy Terrier, A negative MYB regulator of proanthocyanidin accumulation, identified through expression quantitative locus mapping in the grape berry, New Phytologist, (2014) 201: 795–809 doi: 10.1111/nph.12557.
4. A Fournier-Level, T Lacombe, L Le Cunff1, J-M Boursiquot1, and P This, Evolution of the VvMybA gene family, the major determinant of berry colour in cultivated grapevine (Vitis vinifera L.), Heredity (2010) 104, 351–362; 18 November 2009, doi:10.1038/hdy.2009.148.

Why Do We Have White Grape Varieties?

Is your favorite wine a Chardonnay, Riesling, or one of our favorites, Chenin Blanc? I did not know this until I took the U.C. Davis online course, that if it was not for a certain genetic phenomenon, the world would be full of only red grape varieties. I looked into this a little further and learned some interesting factoids.
First of all, the red color in grapes is attributable to the anthocyanins located in the grape berry skin.¹
Just as I did when blogging about red wine color, I'm going to break up this blog about white grapes into little pieces otherwise the blog will become too long and difficult to follow.
So, to recap: The production of anthocyanin, which is responsible for red color in wine is after the enzyme leucocyanidin dioxygenase or LDOX. In the figure below, the expression of mRNAs homologous to each of the anthocyanin biosynthesis genes was determined in the white varieties Riesling, Muscat Gordo, Semillon, Chardonnay, and Sultana as well as the red varieties Cabernet Sauvignon, Pinot Noir and Shiraz using northern blot analysis.¹

The northern blot experiment clearly showed that none of the white varieties expressed anthocyanins as shown by the lack of expression of UFGT (UDP glucose-flavonoid 3-o-glucosyl transferase. Furthermore, there was a difference in expression of genes in the white varieties between Riesling, Semillon and Chardonnay versus Muscat Gordo and Sultana.
When this paper was written in 1996, the authors speculated that:

• It is quite likely that the white grape has arisen independently a number of times from different red varieties
• The mutations could be different in each case so it is not surprising that patterns of gene expression were different in the various white varieties
• Loss of anthocyanin synthesis can arise by mutations in individual structural genes in the flavonoid pathway
• Loss of anthocyanin synthesis can arise by alterations of regulatory genes controlling expression of a number of the structural genes

In the world of scientific investigation, this is ending the experimental work in a mystery. Stay tuned for updated experiments that give more insight into why white grape varieties exist in our world today.
References:
1. Boss P, Davies C, Robinson S (1996b), "Expression of anthocyanin biosynthesis pathway genes in red and white grapes", Plant Mol Biol, 32:565 - 569.
2. Lijavetzky et al., 2006, Mol. Genet. Genomics, 2006: 427-435.
3. José Tomás Matus, Felipe Aquea and Patricio Arce-Johnson, BMC Plant Biology, 2008, 8:83.
4. Yung-Fen Huang, Sandrine Vialet, Jean-Luc Guiraud, Laurent Torregrosa, Yves Bertrand,Veronique Cheynier, Patrice This and Nancy Terrier, A negative MYB regulator of proanthocyanidin accumulation, identified through expression quantitative locus mapping in the grape berry, New Phytologist, (2014) 201: 795–809 doi: 10.1111/nph.12557.

Recap: Why Do We Have Red Wines?

About a year ago, I learned the answer to why we have white wines. (One answer: they come from white grape juice or from red grapes where there was no skin contact in the making of the wine.)
I found a very well written research paper and started to create a blog about it and the blog became a mile long. I decided to approach what seems to be an easy answer in a stepwise fashion so I took the opposite approach, writing first about how red wines get their color:
       Anthocyanins Give Red Wine Their Color
I couldn't stop at there because I wanted to explain how anthocyanins were produced and so I wrote the following blogposts about anthocyanin production beginning with the amino acid phenylalanine and proceeding through the Flavonoid Pathway:
       Why is Red Wine Colored Red
I then found another reference that looked at both the General Phenylpropanoid Pathway and the Flavonoid Pathway in more detail and felt compelled to share this:
       General Phenylpropanoid/flavonoid Pathway
Finally, I was able to blog about how Boss et al. determined that anthocyanin was produced only in the grape berry skin, based on some elegant Northern blot experiments:
       Anthocyanin Production in Grape Berry Skins
Stay tuned for the next blogpost which will use this information on red wine color to explain how the world came to have white grapes and white wine.
References:
1. Boss P, Davies C, Robinson S (1996b), "Expression of anthocyanin biosynthesis pathway genes in red and white grapes", Plant Mol Biol, 32:565 - 569.
2. Lijavetzky et al., 2006, Mol. Genet. Genomics, 2006: 427-435.
3. José Tomás Matus, Felipe Aquea and Patricio Arce-Johnson, BMC Plant Biology, 2008, 8:83.
4. Yung-Fen Huang, Sandrine Vialet, Jean-Luc Guiraud, Laurent Torregrosa, Yves Bertrand,Veronique Cheynier, Patrice This and Nancy Terrier, A negative MYB regulator of proanthocyanidin accumulation, identified through expression quantitative locus mapping in the grape berry, New Phytologist, (2014) 201: 795–809 doi: 10.1111/nph.12557.