Sequestering Key Plant Hormone - C&EN Global Enterprise (ACS

Mar 29, 2013 - Researchers have long known that the plant hormone auxin, or indole-3-acetic acid, regulates a broad range of biological functions, inc...
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NEWS OF THE W EEK

SOLAR FIRMS SCALE BACK MANUFACTURING: First Solar,

SunPower cut production

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voltaics firm, said last week that it will restructure its operations to reduce capacity and shift production to more efficient facilities. The announcement came one day after a similar statement from SunPower, a maker of crystalline silicon solar cells with headquarters in San Jose, Calif. First Solar will close a plant in Frankfurt in the fourth quarter. It will also idle four production lines in Kulim, Malaysia, on May 1. The shutdowns, along with additional personnel reductions in Europe and the U.S., will reduce the company’s workforce by 2,000 positions, or about 30%. The company blamed subsidy reductions in Europe for the changes. Interim CEO Michael J. Ahearn said First Solar is scaled to operate at higher volumes than the market currently deFIRST SOL AR

First Solar will idle four production lines in Malaysia.

IRST SOLAR, an Arizona-based thin-film photo-

NATURE

SEQUESTERING KEY PLANT HORMONE MOLECULAR BIOLOGY: Family of

protein transporters controls auxin levels in plant cells

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ESEARCHERS have long known that the plant

When plants produce PILS proteins (green), indole-3-acetic acid is sequestered inside the endoplasmic reticulum.

hormone auxin, or indole-3-acetic acid, regulates a broad range of biological functions, including flowering, fruit ripening, and root elongation. But they didn’t realize the sophistication and complexity with which plants coordinate the levels and location of this potent hormone in cells, says Jürgen Kleine-Vehn, a plant biologist at the University of Natural Resources & Life Sciences, in Vienna. Kleine-Vehn and his colleagues have discovered a new family of proteins that fine-tunes the levels and location of auxin in plant cells by reversibly sequestering it inside the endoplasmic reticulum (Nature, DOI: 10.1038/nature11001). In addition to clarifying WWW.CEN-ONLIN E .ORG

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mands. “The solar market has fundamentally changed, and we are quickly adapting our market approach and operations to maintain and build upon our competitive advantage,” he explained in a press release. Meanwhile, SunPower executives told investors that the firm is accelerating its shift to production lines that produce photovoltaics at lower costs, including the consolidation of two facilities in the Philippines into one. Last November, the company said it planned to cut costs by 10% in the next year to deal with sinking prices and demand. The average selling price of crystalline silicon photo­ voltaic modules fell from $1.80 per watt to 90 cents in 2011, according to GTM Research, a market analysis firm. First Solar’s cadmium telluride thin-film modules enjoy a price advantage over traditional modules, but cheap supplies of polysilicon and competition from Chinese solar-cell makers have narrowed the difference. The company plans to shrink manufacturing costs to 70 cents per watt by the end of the year. SunPower expects to reduce its cost to 86 cents per watt by then. First Solar may be able to weather the pricing storm thanks to revenues from utility-scale solar projects it is developing, pointed out Jonathan Dorsheimer, an analyst at investment bank Canaccord Genuity, in a note to investors. But for all producers, reducing costs is a must, he wrote. “While difficult, right-sizing the business and attempting to lower the cost structure is clearly the right thing to do: This market has been ruthless to higher cost suppliers—see the bankruptcies of Evergreen Solar, Q-cells, Solon, etc.”—MELODY BOMGARDNER

the biology of an important plant hormone, the work may eventually enable scientists to use the newly discovered transporters to control growth of agricultural crops. Kleine-Vehn’s team guessed that plants might have a previously unrecognized level of regulation for auxin. They used bioinformatics to search the genome of the flowering plant Arabidopsis thaliana for proteins capable of binding auxin or auxin derivatives and discovered what they call the PILS family of seven genes. Then they looked in plant cells for locations where PILS proteins are expressed and discovered them embedded in the endoplasmic reticulum. The PILS transport proteins help control levels of the auxin indole-3-acetic acid in the plant cell’s cytosol without degrading the valuable hormone. Each of the seven different transporters is expressed to control different aspects of auxinrelated plant biology, from stem growth to root branching. “Auxin is so critical to plant development,” comments Mark Estelle, a plant biologist at the University of California, San Diego. “But until now we’ve known almost nothing about where auxin is in a plant cell. It’s really exciting” to learn where it’s found, he says.—SARAH EVERTS

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