NDSU Dry Bean Breeding Update: What We Know Today About the

Slow-Darkening Gene?

JUAN M. OSORNO, Ph.D.Dry Bean Breeder/Geneticist

Department of Plant SciencesNorth Dakota State University

Fargo - ND

The Root of the Problem:“We Eat With Our Eyes”

The Problem With Darkening/Browning

• Public perception: – Consumer: dark beans = old - longer cooking time– Grower: dark beans = poor germination/vigor

• A common issue in:– Many market classes (pinto, cranberry, pink, LRK, etc.) – Other legumes/crops (soybean, faba beans)– Fruits/vegetables (grape, apple, potato, banana, avocado)

• Seed darkening negatively affect prices • Several factors may cause seed darkening:

– Environment: light, temperature, rainfall – Storage– Variety– Diseases

Beninger et al., 2005

https://grandpappy.org/hfoodbea.htm

2 Types of Dark Beans• 1- Beans get dark over time:

– Natural oxidative process.– Storage conditions will have a direct effect.

• 2- Fresh beans can get dark due to:– Harvest delays– Bad weather during harvest

Seed Darkening• Oxidative process of Proanthocyanidin

compounds within seed coat:– a.k.a. condensed tannins– polyphenolic compounds (kaempherol,

quercetrin, etc.)– Flavonoid pathway

• What are flavonoids and why plants have them?

– Family of secondary metabolites– ~5000 flavonoids discovered – Responsible for colors in food– Other functions?

• Chemical and induced defense mechanisms against plant stress

• UV light protection

Freixas et al., 2017

Chen et al., 2015

ProanthocyanidinsRelated to Seed

Darkening in Cranberry Bean(Freixas et al., 2017)

A Little Bit of History

• For humans, food color is important!• In the case of beans, Native Americans

recognized, appreciated, and selected beans with attractive and stable seed coat colors throughout the Americas (heirloom beans).

• Bright seed color is a common feature of most of the highly-priced landraces/market classes.

http://udg.mx/sites/default/files/img_noticias/150525_r.p._manual_el_cultivo_de_frijol_en_jalisco_ag_6.jpg

http://montalvans.com/wp-content/uploads/2015/01/LN_17640_FRIJOL_DE_SEDA_SALVADORENO_4LBS1.jpg

http://www.midia.com.co/sites/default/files/styles/product_detail/public/2016-07/fr%C3%ADjolGargamento.png?itok=yWexEw1W https://i.pinimg.com/474x/04/32/e2/0432e2f7225d55e5

c921a1130649eed5--beans.jpg

https://topnaturalremedies.net/wp-content/uploads/2014/10/White-Beans-morgue1.jpg

http://images.lider.cl/wmtcl?source=url[file:/productos/518265a.jpg]&sink

http://i.anunciosya.com.mx/i-a/6yyg-4.jpg

Flor de Mayo Yellow/Canario/Garbancillo

Cranberry

Coscorron

https://www.embrapa.br/bme_images/o/87240080o.jpg

Carioca

• 1980’s: Bean scientists (S. Singh) at CIAT-Colombia noticed some germplasm accessions maintaining good seed color after years of storage.

• 1990’s: First crosses made at CIAT mostly using landraces from the Mexican highlands – Pintos: G17341 and Zacatecano

Early Breeding Efforts

Early Breeding Efforts• Acosta-Gallegos et al. 2004:

– CIAT+INIFAP Mexico released the first slow darkening pinto cultivar ‘Pinto Saltillo’

– Still the most popular variety in Mexico today!• Junk-Knievel et al. 2005:

– Crop Develop. Center at Univ. of Saskatoon: breeding line 1533-15

– Commercially known as CDC-WM-1– Suggested J gene as responsible for sd trait

• Singh et al. 2006: – Univ. of Idaho release SDIP-1

Breeding for New Varieties• Junk-Knievel et al. 2008: Genetic control

of the slow darkening gene is understood– Single-recessive gene (sd), different from J– Same gene in Pinto Saltillo

• Elsadr et al. 2011: – Same gene in SDIP-1– Better understanding of gene interactions

• J gene: Non-darkening• sd gene: slow darkening gene• Recessive epistasis?

How the Gene Works?• Naturally occurring gene (non-GMO)• Used/transferred via conventional

breeding• Recessive gene:

– (SD x RD) = F2 :1 out of 4 plants will be SD• Gene related to flavonoid production

pathway is “broken” (loss of function)• Good analogy: Albinism

UVC-light Fast TestJunk-Knievel et al., 2007

Felicetti et al., 2012

Breeding for new varieties• Felicetti et al., 2012:

– sd gene mapped in chromosome Pv07– Diagnostic DNA markers developed

• Bett et al. 2014: CDC-WM-2• Osorno, Miklas, et al., 2016: Joint release

between NDSU and USDA-ARS: – ND-Palomino

• Provita 2016: – Radiant and Vibrant (ADM-Seedwest)

• Brick et al., 2017: Staybright

Current Status of Slow Darkening Pinto Varieties

• Pinto Saltillo: – Photo-period sensitive (won’t flower in long days)

• SDIP-1– Poor agronomic performance + bad seed shape

• At least 6 varieties commercially available: CDC-WM-1*, CDC-WM-2*, ND-Palomino, Staybright, Radiant, Vibrant.

• In most cases, either 1533-15 or SDIP-1 is the source for the sd gene!– They all go back to CIAT G17341: very small seed!

*Canada only?

CIAT G17341 is a Small Seeded Pinto

ND-PalominoG17341

Current Status of Slow Darkening Pinto Varieties

• Seed yield of these varieties is similar to commercial regular darkening pintos commonly grown in the region.– Superior agronomic performance compared to

original sources of the sd gene shows that genetic progress has been accomplished!

– Improvements in:• Higher seed yield• Larger seed size• Upright plant architecture

• More/new genetics in bean pipelines!

ND-Palomino

ND-Palomino Buster

2012 harvest – Photo taken in 2017

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La Paz Windbreaker ND-Palomino Lariat Stampede SDIP-1 1533-15

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Seed Yield (Cwt/Acre) of Pinto Bean Varieties Across 54 Environments (2012-2017)

Original sources

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Environment or Location

Yield Stability of ND-Palomino and Other Commercial Varieties Across 41 Environments (2012-2016) in ND and MN

ND-Palomino

Stampede

Lariat

La Paz

Windbreaker

Mean

• SD pintos tend to cook faster– K. Cichy: ~4 min. faster than RD

pintos– Important for canning industry!

• SD pintos tend to germinate faster – Flavonoids are related to seed

dormancy– Quicker water absorption?– Effect on days to maturity

• SD pintos tend to be earlier?

Freixas et al., 2017

Current Status of Slow Darkening Pinto Varieties

Under controlled conditions

Current/Future Challenges• Need to keep SD pintos separated has created

some challenges for the industry– Avoid comingling SD + RD– Careful handling during seed milling/conditioning– Similar cases occurred in sunflower and peanut

• Lack of flavonoids could make SD pintos less resilient to: – Diseases?– Abiotic stress (cold, flooding, drought)?– Early vigor?

J. Jones, ADM-Seedwest

Soil Temperature at Planting

More Research is Needed to Answer all These Questions:

• Role/function of flavonoids (plant/human nutr.)• Are SD less resilient than RD pintos?

– Biotic/abiotic stress– Harvest/Seed conditioning

• Moving the sd gene into other market classes (cranberry, pink, LRK, etc.)– New SD carioca bean in Brazil

• Using the Non-Darkening gene (J) instead of the Slow Darkening (sd)?– Univ. of Guelph: focused on J only!

We Are Not the Only Ones Trying to Solve Darkening/Browning

https://www.arcticapples.com/

Thank you!

• Research Specialists:– Jody Vander Wal– Mike Kloberdanz (Res. Feb. 2017)– John Posch (May 2017)

• Postdoctoral Scientists:– Dr. Ali Soltani (Res. Feb. 2017)– Dr. Stephan Schroder (Res. Oct. 2017)

• Graduate Students:– Katelynn Walter, Luz Montejo, Carlos Maldonado, Daniel Restrepo,

Federico Velazquez, Edgar Escobar

• Summer interns/workers