Articles
Breeding impatiens for resistance to impatiens downy mildew (Plasmopara obducens)
Article number
1435_21
Pages
159 – 164
Language
English
Abstract
Impatiens walleriana, commonly known as impatiens, is one of the most popular annual bedding plants and an important source of income for many greenhouse growers and landscapers in the United States and Europe.
However, the advent of impatiens downy mildew (IDM), Plasmopara obducens, changed the plant’s status and economic value. P. obducens is a pathogen that has become virulent against this species of impatiens and is very difficult to manage.
It leaves plants defoliated and commercially unviable.
Oospores allow reinfection to occur and can remain in soil for up to 10 years.
Commercial fungicides are ineffective at eradicating the disease and only temporarily prolong the health of the plant.
By 2011, the pathogen had spread worldwide and become a significant problem in the landscape.
This disease results in wilting, leaf and flower drop and ultimately death of this important bedding plant.
In the past 10 years, sales of Impatiens walleriana have plunged because of this devastating disease.
Due to the downy mildew epiphytotic, there was a critical need for breeding research with impatiens to develop resistance to IDM. We began a breeding program at Cornell University with the objective of generating impatiens with good ornamental traits, in addition to IDM resistance.
In 2015, we successfully confirmed that IDM-resistance is genetically inherited with impatiens.
A traditional breeding program was started to hybridize Impatiens walleriana plants with resistant impatiens species.
We demonstrated that the popular Impatiens walleriana is compatible for cross-fertilization with other impatiens species that are resistant to IDM and that the ornamental qualities of the common impatiens can be combined with the disease resistance of the wild relatives to produce improved plants.
By 2016, two hybrid plants were developed that were resistant to the disease.
These two plants were used for further breeding with the goal of developing seed-propagated lines of impatiens that are resistant to IDM. The new plant products that have been generated from this research will have great potential for the ornamental horticulture industry.
However, the advent of impatiens downy mildew (IDM), Plasmopara obducens, changed the plant’s status and economic value. P. obducens is a pathogen that has become virulent against this species of impatiens and is very difficult to manage.
It leaves plants defoliated and commercially unviable.
Oospores allow reinfection to occur and can remain in soil for up to 10 years.
Commercial fungicides are ineffective at eradicating the disease and only temporarily prolong the health of the plant.
By 2011, the pathogen had spread worldwide and become a significant problem in the landscape.
This disease results in wilting, leaf and flower drop and ultimately death of this important bedding plant.
In the past 10 years, sales of Impatiens walleriana have plunged because of this devastating disease.
Due to the downy mildew epiphytotic, there was a critical need for breeding research with impatiens to develop resistance to IDM. We began a breeding program at Cornell University with the objective of generating impatiens with good ornamental traits, in addition to IDM resistance.
In 2015, we successfully confirmed that IDM-resistance is genetically inherited with impatiens.
A traditional breeding program was started to hybridize Impatiens walleriana plants with resistant impatiens species.
We demonstrated that the popular Impatiens walleriana is compatible for cross-fertilization with other impatiens species that are resistant to IDM and that the ornamental qualities of the common impatiens can be combined with the disease resistance of the wild relatives to produce improved plants.
By 2016, two hybrid plants were developed that were resistant to the disease.
These two plants were used for further breeding with the goal of developing seed-propagated lines of impatiens that are resistant to IDM. The new plant products that have been generated from this research will have great potential for the ornamental horticulture industry.
Authors
M.P. Bridgen, J.E. Keach, V.A. Zayas
Keywords
plant breeding, embryo culture, micropropagation, disease resistance, interspecific hybridization, plant tissue culture
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