The citrus disease Huanglongbing (HLB), meaning "yellow shoot disease" in Chinese and also called citrus greening in English-speaking countries, is the most destructive disease threatening the citrus industry worldwide. Powerful diagnostic tools and management strategies are desired to control it. A new study, 'Small RNA profiling reveals phosphorus deficiency as a contributing factor in symptom expression for citrus Huanglongbing disease', published online today (Friday) in the journal Molecular Plant profiled small Ribonucleic Acids (sRNAs) from both diseased and healthy plants and found that some of these tiny molecules could potentially be developed into early diagnosis markers for HLB. More importantly, the study demonstrates that the diseased trees suffered from severe phosphorus (P) deficiency and that application of phosphorus solutions to the diseased trees significantly alleviated HLB symptoms and thus improved fruit yield in a three-year field trial in southwest Florida.
HLB is caused by the bacteria of the genus "Candidatus Liberibacter". Symptoms of the disease include blotchy mottled leaves, sections of yellow and underdeveloped vegetative growth, premature fruit drop, and in some cases, off-flavoured fruit with aborted seeds. In areas affected by HLB, citrus management costs have increased dramatically in the last few years: in the US alone, annual HLB management-related costs have totalled around $1.2 billion and it has been estimated that HLB management has increased citrus production costs by 40-50% in affected areas. These high costs are largely due to the need for more additional treatments to mitigate the disease's effects, and therefore early, rapid, and robust detective methods are required, especially presymptomatic diagnosis.
The study's author, Dr Hailing Jin of The University of California, Riverside, explains, "sRNAs are important gene expression modulators, some of which regulate plant responses to
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