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Plant Biotech Firm Venganza Secures US Patent on RNAi Technology


Plant biotechnology firm Venganza hit a major milestone last week, receiving a US patent on its core technology, which is based on the use of RNAi to create pest and pathogen resistance in crop plants.

With this key piece of intellectual property in hand, the company is now in the process of negotiating licenses to its technology with unnamed “major” companies working in the space, Venganza President Charles Niblett told Gene Silencing News this week.

The specific details about the Venganza’s efforts with these ag-bio firms have not been made public, he added. However, the recently issued patent provides some insights into the company’s focus.

The patent — No. 8,461,416 — covers the creation of plants that express RNAi constructs against genes essential to plant pests and diseases, and is based on proof-of-concept work the company conducted to address the effects of the fungus Phytophthora infestans in potatoes.

The fungus was the cause of the Irish Potato Famine in the late 19th century, which caused an estimated one million deaths and led to mass emigration. According to Niblett, the so-called late potato blight led to the establishment of plant pathology as a scientific field of study.

P. infestans remains a serious problem for potato growers, especially in developing nations such as India, Indonesia, and Bangladesh, where potatoes have become “an increasingly important nutritional source,” he said.

With funding from the United States Agency for International Development, and in collaboration with the International Potato Center, or CIP, in Peru and Kenya and with Cornell University, Venganza identified genes essential to the fungus, and created transgenic plants expressing double-stranded RNA constructs against those genes.

Niblett noted that the work developing P. infestans-resistant potato plants was primarily to establish proof of concept for Venganza’s RNAi approach. The company is currently identifying other genes essential to the fungus and creating constructs that will be sent to its collaborators at CIP and Cornell for use in creating the transgenic plants.

More advanced in Venganza’s pipeline is its transgenic banana program, which is being conducted in collaboration with Uganda’s National Agricultural Research Organization, also with USAID funding, Niblett said.

That effort is focusing on developing bananas resistant to two fungal threats: Black Sigatoka and Fusarium wilt.

The first, Niblett said can be addressed with fungicides, but doing so is expensive, accounting for up to 25 percent of the “cost of the bananas that you buy in the store.” Notably, the expense of combating Black Sigatoka can be prohibitive for small famers in local markets.

Fusarium wilt, meanwhile, has long been a problem for the banana industry, and led to a shift in the type of bananas grown during the 1950s from the Gros Michel cultivar to another, called Cavendish, that was resistant to the fungus.

However, a new strain of Fusarium that attacks Cavendish bananas has appeared, creating the need for alternate ways to control the disease, Niblett said.

“A tropical race of this fungus changed the banana industry once, [and] it looks like it’s going to be changed again,” he said. “We’re hopeful that the type of research we’re doing will have application, both as a provider of nutrition in developing countries … but also in sustaining the export banana industry in Latin America.”

Earlier this year, Venganza and its Ugandan collaborators published data on the antifungal activity of dsRNAs against the pathogens behind Black Sigatoka and fusarium wilt. According to those findings, which appeared in Pest Management Science, the dsRNAs were able to silence target genes in vitro, and the team was able to identify “promising targets for RNA-mediated resistance in banana.”

Niblett said that Venganza has now provided eight RNAi constructs to its collaborators at NARO, who have used them to create a number of transgenic plants currently being propagated for screenhouse and greenhouse testing, he said.

If all goes well, the plants could be ready for field testing — performed under both Ugandan and USAID regulations — in 2014, he added.

Venganza also has earlier-stage programs underway focused on fighting wheat and corn diseases and pests, including one looking at maize lethal necrosis, a corn disease that results from the synergistic interaction between two viruses: sugar cane mosaic virus and maize chlorotic mottle virus.

Niblett was part of the research group that first discovered this disease in Kansas during the 1970s, but he noted that it was ultimately controlled through the implementation of agricultural techniques such as crop rotation.

However, in 2011, maize lethal necrosis appeared in Kenya, where it has destroyed a significant portion of that country’s maize crops. “Now, it’s moved to Tanzania and Uganda, and it may have been found in Burundi,” he said.

In partnership with the International Maize and Wheat Improvement Center in Mexico and Kenya and with scientists at the US Department of Agriculture, Venganza is working to develop corn resistant to this disease.

Despite its success thus far in attracting interest in its technology — from non-profit and government organizations, as well as industry — Venganza aims to remain a small player in the plant biotech field, Niblett noted.

“We don’t have any intention to try to compete with large companies,” he said. “We simply want to collaborate through licensing arrangements, collaboration agreements, [and] research and development agreements. We see ourselves as a collaborator, not a competitor.”