HLB, Lemons and Oranges

Ernie NeffResearch

A group of scientists working in California, New York and Washington has found that Lisbon lemon trees had less of a molecular response than Washington navel orange trees to the pathogen that causes HLB. That pathogen is Candidatus Liberibacter asiaticus (CLas). In part, this might be because leaves of infected lemons tended to accumulate micronutrients, which led to less of an impact on photosynthesis. Additionally, protease inhibitors, important for plant defense, were upregulated in lemons.

The findings were found via a comprehensive molecular analysis.

“These results may be important for developing varieties of citrus that are more tolerant or perhaps resistant to the HLB pathogen,” said Carolyn Slupsky, a University of California Davis-based systems biologist involved with the research. “Our research highlights some key features that differentiate more tolerant from more susceptible varieties of citrus and may be used to develop new cultivars that are resistant to the effects of this pathogen.”

This study is the first to analyze the impact of HLB, also called citrus greening disease, on citrus metabolism prior to symptom development. “Understanding early response is important, as it may also help in developing technologies to detect the disease earlier,” Slupsky said.  

Learn more about this research from an article titled Multi-omics Comparison Reveals Landscape of Citrus limon and Citrus sinensis Response to Candidatus Liberibacter asiaticus, published by the American Phytopathological Society. That article states that the information presented “may be important for developing varieties that are more tolerant to CLas, espcially in California, because the majority of fruit grown commercially is for fresh consumption.” The article notes that HLB was discovered in California in 2012, seven years after its discovery in Florida. It adds that California “is beginning to see a rapid increase of citrus greening disease.”

Florida’s citrus industry has suffered far more than the California and Texas citrus industries as a result of HLB.

Source: American Phytopathological Society.

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