Annual Progress Report on Malting Barley Research March, 2002

96
ATTEMPTS TO TRANSFORM NEWER CULTIVARS WITH GENES AFFECTING
TRICHOTHECENE TOXIN AND FHB LEVELS
Lynn S. Dahleen and M. Manoharan
Cereal Crops Research Unit, USDA-ARS and
Dept. of Plant Sciences, NDSU
Objective
To produce transgenic commercial barley cultivars that express anti-toxin genes which
reduce DON levels and Fusarium infection.
Introduction
Fusarium head blight (FHB), caused primarily by Fusarium graminearum, has been one of
the most destructive diseases of barley since the early 1990s, resulting in huge economic
losses for growers (McMullen et al.1997). Of particular concern is the production of
deoxynivalenol (DON), a potential pathogen virulence factor (Desjardins et al. 1996,
Proctor et al. 1995, 1997) that is harmful to humans and livestock (Busby and Wogan 1981).
Chemically modifying DON or transporting it out of cells could improve resistance to FHB
while at the same time reducing DON accumulation in grain. FsTri101 (TriR), isolated from
F. sporotrichioides, encodes a 3-OH trichothecene acetyltransferase that converts DON to a
less toxic acetylated form. PDR5, an ATP-binding cassette transporter isolated from
Saccharomyces cerevisiae, acts as an efflux transporter, shunting DON across the plasma
membrane from the interior of the cell. We have transformed the commercial malting barley
cultivar Conlon with the Tri101 and PDR5 genes with the aim of reducing DON level in
infected grain.
Methodology
Development of the transgenic lines was described in last year’s report. Experiments
have resulted in seven transgenic events for Tri101 and six events for PDR5. A
transformation event consists of all the plants regenerated from one callus clump that was
bombarded with the genes. Four of the events for each gene resulted in tetraploid plants.
Lines from the three diploid Tri101 events and the two diploid PDR5 events were
advanced two generations by self-pollination and seed used for field trials in 2001. Ten
lines each of the five diploid transformation events were planted in short rows in two
replicates. One replicate was planted in the misted, inoculated nursery at Langdon, ND
and one replicate was planted just outside the inoculated nursery, so each would have
different levels of FHB. Non-transgenic Conlon was planted every fifth row. Traits
measured included height, % FHB, seed weight per 100 spikes, and DON concentration.
Greenhouse tests are underway. Plants are spray inoculated, held in a mist chamber for
24 hours, and then scored for % FHB 14 days later. The two lines from each
transformation event that had the lowest FHB in the field have been tested and additional
lines are being grown for further testing. After harvest, seed will be sent to the NDSU
Barley Malt Quality Lab for DON measurements.