Transgenic Sunflower - Genetics, Genomics and Breeding of Crop Plants - page 296

sexually-transferred to crops to create non-GM sunflowers, under the
commercial name of Clearfield ® (Tan et al. 2005). Another resistance source,
obtained from mutagenesis of domestic sunflower, is promising in order to
produce high yielding commercial hybrids, because of the absence of wild
background (Sala et al. 2008). Gene expression of tolerance in these new
varieties allows herbicide application at the advanced stages of crop
development, thus controlling the majority of weeds including broomrape
(Gressel et al. 1996). Some other groups of herbicides have also proven
effective against this weed, including glufosinate-ammonium (Valkov et al.
1998) and glyphosate (Collin 1999).
There are many cases in the world of weed populations displaying
resistance to herbicides that inhibit AHAS (95 cases, including wild
Helianthus , http://www.weedscience.org/summary/MOASummary.asp ) and also
to other herbicides. There is a need to keep on searching for new control
strategies. Given the absence of glufosinate-ammonium resistance among
weeds, a good long-term strategy could involve incorporating this tolerance
through GM sunflower. Moreover, two homologous “ bar ” and “ pat ” genes
that codify phosphinothricin acetyltransferase (PAT) enzyme have been
shown to be safe for this purpose as they do not cause allergy and are
rapidly degraded in the intestine (Hérouet et al. 2005). Glufosinate-
ammonium tolerance would also be a good strategy for the control of the
remaining weeds, mainly cosmopolitan, associated with sunflower crop,
with predominance of those of the same family Asteraceae ( Table 9-4 ).
Table 9-4 Research articles about sunflower crop biotic adversities published during five
years (CAB 2002-2007).
Group Species Articles

# Name # %

Weeds
Orobancheceae 6 Orobanche spp. 2 6 3 5

Chenopodiaceae 4 Chenopodium album 12 16

Amaranthaceae 5 Amaranthus spp. 11 1 5

Asteraceae 8 Ambrosia artemisiifolia 10 13

Total weeds 8 6 7 5 17

Pests
Lepidoptera

27 Helicoverpa armigera 22 11

Coleoptera (root) 2 0 Agriotes spp. 9 5

Coleoptera (shoot) 1 2 Zygogramma exclamationis 4 2

Birds (Icteridae) 8 Agelaius phoeniceus 3 2

Total pests 103 191 24

Diseases
Fungi

2 8 Sclerotinia sclerotiorum 70 19

Plasmopara helianthi 51 14

Diaporthe helianthi 41 11

Alternaria helianthi 39 10

Viruses 4 Sunflower necrosis virus (SNV) 1 9 5

Bacteria 3 Pseudomonas 5 1

Total diseases 3 5 260 59