Understanding the science

Creating value through unique plant opportunities.

Novel endophyte technologies

Harvesting and sowing seeds are activities as old as civilisation. Innovative products and technologies add value to these ancient practices, and bring new opportunities to New Zealand livestock farmers.

Grasslanz Technology Limited is a wholly owned subsidiary of AgResearch. Grasslanz Technology develops, promotes and licences proprietary forage grasses and legumes, endophytes, and applied biotechnology to seed companies. These products are sold to farmers under licence from Grasslanz Technology by the seed companies.

Endophyte developments have been a major focus for Grasslanz Technology in recent years. Research undertaken by AgResearch (Grasslanz Technology’s parent company) in the endophyte area is world leading, and the technology has provided millions of dollars of benefit to New Zealand primary industries since the release of the novel endophyte AR1 in 2000. The research for the development of AR1 was a major team effort by mycologists, chemists, agronomists, entomologists and plant breeders. Research into the identification, understanding, testing and commercialisation of an endophyte strain takes the best part of 20 years.

The endophyte programme undertaken by Grasslanz Technology and AgResearch goes through a number of key stages. Endophytes have been isolated from grasses collected from around the world. They are identified and classified, and over the years a picture has developed as to how individual endophyte strains are related to one another. Once an endophyte strain is identified, the spectrum of chemical compounds it produces is determined, along with the impact these have on insects. Endophyte strains with a good range of insect tolerance are agronomically evaluated in a number of environments and various management styles. Endophytes that are agronomically as good or superior to standard (common toxic) endophytes are then subjected to intensive animal safety and performance testing. To be commercialised novel endophyte strains need to be superior to standard endophytes in these aspects of testing.

The final process is to develop seed production, processing, prolonged storage, and quality assurance systems. This is to ensure that the correct and a viable endophyte can be delivered to the farmer. It is important to remember that endophytes are a perishable product and a lot of care is required at the seed production, processing, and storage phases to ensure farmers actually receive the novel endophytes they purchase in their seed on their farms.

What is an endophyte?

Endophyte is a naturally occurring fungus whose complete life cycle occurs within grasses such as perennial ryegrass and tall fescue. Most New Zealand ryegrass pastures are infected with endophyte. The endophyte fungus grows between the cells of the host plant, drawing nutrients from it but in return conferring resistance to insect pests, drought tolerance, and protection from overgrazing. Such a mutually beneficial relationship is known as symbiosis. Endophytes produce chemical compounds known as alkaloids, which confer pasture pest resistance, but which can also cause animal health problems. Peramine deters in particular feeding and egg laying of Argentine Stem Weevil, but has no known effects on animal health. LolitremB deter Argentine Stem Weevil larval feeding but cause Ryegrass Staggers. Ergovaline gives resistance to Black Beetle, but causes heat stress, especially in warm humid conditions

Novel endophytes

Novel endophytes are selected endophyte strains that have known and understood alkaloid chemical compound profiles. It is known what impact these compounds have on insect pests, the agronomic performance and persistence of the ryegrass and tall fescue plants, and the health and performance of animals grazing plants containing the novel endophyte strain. Novel endophytes can be incorporated into elite cultivar germplasm either by an inoculation process or by breeding and selecting with plants that contain the novel endophyte strain.

Endophyte strains commonly present in New Zealand ryegrass pastures contain the compounds lolitrems, peramines and ergovalines. The selected strain, ‘AR1’, contains peramine which gives tolerance to Argentine stem weevil and some tolerance to black beetle when plants are well established. AR1 does not contain lolitrem or ergovaline so that there is enhanced animal performance. Endo 5 contains peramine but no lolitrems. They do contain some level of ergovaline which allows for agronomic robustness, especially in areas where black beetle is an issue.

The most recent novel endophyte, ‘AR37’, does not contain lolitrems, peramine, or ergovaline, but does have a unique group of compounds called epoxy-janthitrems. Epoxy-janthitrems confer protection against a wide range of insect pests (Argentine stem weevil, black beetle, root aphid, pasture mealy bug and porina). A point of note is that AR37 controls the Black Beetle lifecycle at the adult stage rather than at the larval stage. Testing to date has shown ryegrass infected with AR37 to be more persistent and productive than pastures infected with standard endophyte, with livestock performance levels similar to AR1 and nil endophyte. While AR37 does not produce the alkaloid LolitremB it can cause ryegrass staggers in grazing livestock. In grazing trials at Lincoln the incidence of ryegrass staggers on pure ryegrass with AR37 has been less frequent and usually only half as severe as on ryegrass with standard endophyte. However, these trials have shown than spasmodically AR37 can cause serious staggers (Fletcher & Sutherland 2009: Proc NZGrassland Assn, 71: 127-33. However, to date no ryegrass staggers have been reported on any class of cattle on AR37 in trials or on commercial farms. Due to the fact that no trial work has been undertaken on deer and horses, pastures with AR37 are currently not recommended for those livestock classes or other untested species.

Novel endophytes are protected by patents
The development of novel endophytes is an expensive process over a long period of time, and they do offer farmers significant agronomic advantages and subsequent economic benefits. Due to these factors Grasslanz Technology and AgResearch have obtained Intellectual property protection in the form of patents.

What many farmers and seed growers may not be aware of, is that only companies who have a licence can produce or sell the cultivars containing novel endophytes. At the individual farmer level the patent means that seed containing novel endophytes like AR1 is protected by law. Farmers who harvest and re-sow or on-sell novel endophytes such as AR1 and AR37 to companies other than licence holders are very likely to be in breach of the patent and this may lead to prosecution under NZ law.

Choosing a Ryegrass Endophyte

Diploid ryegrasses

Insect	AR1	AR37	Standard endophyte	Without endophyte
Argentine stem weevil		1		-
Pasture mealybug				-
Black beetle				-
Root aphid	_2			-
Porina	-	()3	3	-

Tetraploid ryegrasses4

Insect	AR1	NEA2	AR37	Endo5	Without endophyte
Argentine stem weevil		1	1	1	-
Pasture mealybug		()			-
Black beetle					-
Root aphid	_2	()		()5	-
Porina	-	Not tested	Not tested	()3	-

Key to tables
-	No control
	Low level control: Endophyte may provide a measurable effect, but is unlikely to give any practical control.
	Moderate control: Endophyte may provide some practical protection, with low to moderate reduction in insect population.
	Good control: Endophyte markedly reduces insect damage under low to moderate insect pressure. Damage may still occur when insect pressure is high.
	Very good control: Endophyte consistently reduces insect populations and keeps pasture damage to low levels, even under high insect pressure.
( )	Provisional result: Further results needed to support the rating. Testing is ongoing.

Notes on tables:

1. These endophytes control Argentine stem weevil larvae, but not adults. While larvae cause most damage to pastures, adults can cause damage to emerging grass seedlings, so use of an appropriate seed treatment is recommended for sowings in stem weevil prone situations.
   
   
2. AR1 plants are more susceptible to root aphid than plants Without endophyte.
   
   
3. Control of porina in pastures only applies to the ryegrass component. Other species that are palatable to porina (such as white clover) will still be damaged.
   
   
4. There is much less information on their effect of endophyte in tetraploid ryegrasses on insects than for diploids. Tetraploids are generally more susceptible to Argentine stem weevil and the insect resistance provided by endophyte may not be as strong, although this may vary between varieties. These ratings are based on available data but require further confirmation.
   
   
5. Control of root aphid by tetraploid cultivars with Endo5 varies. Banquet II Endo5 has moderate control (), whereas Quartet II Endo 5 has no control.