Sunday, November 22, 2015
Drought-resistant pineapple has clues for drought resistance in other crops
Drought is responsible for most of the world’s crop losses,
and researchers say that new work on drought-resistant pineapple is providing clues.
“Understanding the mechanisms that plants have evolved to
survive water stress is vital for engineering drought tolerance in crops,”
write the authors of a new study in the
journal Nature Genetics.
(Image: Pineapple [Ananas comosus {L.} Merr.]. Source: University of Hawai`i.)
Pineapple, the world’s second most important tropical fruit
after bananas, is a member of the bromeliad family—the only bromeliad to
produce a commercially important fruit. The bromeliads and the grasses are
descended from a common ancestor.
An international team of researchers, including two from the
University of Hawai`i at Mānoa, sequenced the pineapple genome. The two are Nancy
Jung Chen and Robert Paull, with the university’s Department of Tropical Plant
and Soil Sciences in the College of Tropical Agriculture and Human Resources. The
project’s leader, Ray Ming, is a former University of Hawai`i researcher who is
now with the University of Illinois.
They sequenced wild pineapple as well as two commercial
species—an old high acid variety used in canned pineapple and a newer low-acid
variety used primarily for fresh fruit sales. Pineapple has the scientific name Ananas
comosus.
The researchers are looking at flower metabolism, sugar
production and other features, but an important research objective is
understanding pineapple’s drought tolerance, according to the University of
Hawai`i’s press release on the project.
“The plant possesses an alternate photosynthetic pathway
that concentrates carbon dioxide during the night when water loss is less. This
reduced water loss leads to high water-use efficiency,” the release says.
The name scientists use for this process is crassulacean
acid metabolism or CAM.
Pineapples convert carbon-dioxide into malic acid at night ,
and then use it in the daytime while they keep their stomata closed to preserve
moisture.
Here’s how the scientists say that: “CAM plants can keep
their stomata closed during the daytime while the stored malic acid is
decarboxylated and the carbon dioxide released is refixed through the
Calvin-Benson cycle, greatly reducing water loss through evapotranspiration.”
Stomata are plant pores from which gases, including
moisture, can be exchanged. Closing them in daylight can prevent moisture loss during hot,
dry, sunny periods. Malic acid is an organic acid found in all fruits,.
The authors suggest that the drought resistance of pineapple
could be conveyed via genetic engineering into other crops: “This work provides
the first detailed analysis of the expression and regulation patterns of genes
associated with CAM and could ultimately be used to engineer better (water-use
efficiency) and drought tolerance in crop plants.”
Drought tolerance has been a key goal of crop plant breeding and genetic engineering worldwide.
Pineapple is originally a Central American plant, first reported by Europeans on Christopher Columbus' voyage. It once was one of Hawai`i's economic mainstays, second to sugar.
"Today, pineapple is cultivated on 1.02 million hectares of land in over
80 countries worldwide, and 24.8 million metric tonnes of fruit are
produced annually with a gross production value approaching $9 billion. Pineapple has outstanding nutritional and medicinal properties," the paper's authors write.
© Jan TenBruggencate 2015
Posted by Jan T at 9:53 AM
Labels: Agriculture, Botany, Climate Change, Solar, Sustainability, technology, Weather, Wind
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