Orobanche Inflorescences 25 Years Later Destructive Parasitic Weeds

Volcani Institute, Israel Newe Yaar Research Center Many centuries ago Orobanche inflorescences 25 years later Destructive parasitic weeds

Cuscuta campestris Broomrapes (Orobanche, Phelipanche) are root parasites The most destructive species

Orobanche cernua Phelipanche Orobanche cumana Orobanche ramosa crenata

Phelipanche aegyptiaca (o. minor)

Phelipanche ramosa

Attack more than 30 crops Including Ornamentals and weeds

This obligate holo parasite is widespread

Orobanche spp. is a host specific Parasitic weeds are difficult to control by traditional means

Seed setting

Inflorescence germination

Life cycle

Spider like tubercle Tubercles

Once conditions are optimal, the parasite seeds will germinate How the parasite starts its seeds germination?

Host Plant Inflorescence Flowering and development Seed setting

Aerial phase Seeds Phosphate starvation Emergence Root exudates From soil Seed dormancy Strigolactones

Conditioning

Seed Germination

Attachment to host root Mycorrhizal interaction Tubercle development Underground phase Sophisticated life style

arbuscular mycorrhizal

Strigolactone is a stimulant for the parasite seed germination Potato field damaged by P. ramosa O. crenata in carrot

In carrot SDEAH ELIAHO O. crenata in pea Sunflower field damaged by O. cumana P. aegyptiaca reduced quality and yield quantity in tomato fields Cabbage highly infested with P. aegyptiaca

Food crop losses from broomrape Could be estimated to reach more than 2 billion dollars annually in the Middle East alone Distribution

Several control strategies

Chemical Control  Preventive methods (Methyl bromide)

 Cultural methods

 Physical

 Host resistance Biological Control

 Genetic engineering Fumigation with methyl bromide Control – No fumigation The best long term strategy  Breeding for resistance  engineering resistant crops

– No chemicals to apply – No additional labor or complicated management. – No expensive equipment needed. – Deplete parasite seeds in the soil. • Only a few crop varieties with stable resistance have been developed after decades of conventional plant breeding. • Genetic engineering technology can help if we understand how the parasite and host interact.

Chemical control: Herbicides Foliar application (1-3 times) of glyphosate controlled O. crenata in carrot Application of sulfonylurea herbicides directly to the soil, pre-broomrape attachment, controlled Egyptian broomrape in tomato (Solanum lycopersicum) and potato Herbicides based on sulfonylurea, imidazolinone and glyphosate are effective for controlling Orobanche and Phelipanche spp. Chemical control Imazapic in potato

Persuit, three treatments, 1 gr. \ dunam

Surgery was successful but the patient died!!!

Underground video camera

Underground attachment using Chemical Control, disadvantages: Weeds, crop pests and diseases became resistant to chemical applications

Ideal broomrape control could be Other factors: achieved by new biotechnology

 Global warming Safety  Environmental Pollution  Availability  $ Cost Novel control strategy

Approaches

Plant arming by toxic Gene silencing and editing compounds

Non-transgenic Transgenic

(Aly et al., 2006); (Hamamouch et al., 2005) key-gene silencing of the parasite through the host plant

(b)

Non-Tr

Tr Non-Tr (a) (c) Activity at UC-Davis Geranylgeranyl pyrophosphate

PSY

Phytoene

PDS

ζ-Carotene

ZDS

Lycopene

LCY-B/LCY-E LCY-B

α-Carotene β-Carotene

Strategy: Editing CCD8 in the host plant Using CASPR/Cas 9 CCD7/8

Strigolactones Less infestation by the parasite WaNTED

Dead Not Alive