Grant Information

USE OF RNAI TO MITIGATE RESPONSES OF CITRUS INFECTED WITH CANDIDATUS LIBERIBACTER ASIATICUS (CLAS), ON DEVELOPMENT OF HUANGLONGBING DISEASE (HLB)

Sponsoring Institution Agricultural Research Service/USDA
Status ACTIVE
Funding Source USDA COOPERATIVE AGREEMENT
Reporting Frequency Annual
Project Director MCCOLLUM T G
Accession Number 428190
Project Number 6034-21000-016-08S
Dates 2015-05-01 - 2016-03-31
Recipient Organization UNIVERSITY OF FLORIDA

LAKE ALFRED,FL 33850
Keywords abscission
callose
citrus
endo-glucanase
huanglongbing
polygalacturonase
pyrophosphorylase
rnai
starch
synthase
tristeza
udpg
vector
viral
virus
Research Effort Applied (30%)
Basic (70%)
Developmental (0%)
Classification Parameters
Knowledge AreaSubject of InvestigationField of SciencePercent
203 - Plant Biological Efficiency and Abiotic Stresses Affecting Plants 920 - Orange 1000 - Biochemistry and biophysics 50%
204 - Plant Product Quality and Utility (Preharvest) 999 - Citrus, general/other 1080 - Genetics (excludes breeding) 50%
Goals / Objectives

Determine the effects of RNAi-mediated down regulation of:

  1. callose synthase on callose accumulation in citrus phloem
  2. UDPG pyrophosphorylase on starch accumulation in citrus leaves
  3. enodo-glucanase and polygalacturonase on abscission

Each of these processes occurs in response to infection with involved in the development of Huanglongbing Disease (HLB).

Methods (unparsed)

Citrus tristeza virus (CTV) will be engineered to carry antisense RNA for four genes known to be involved in three HLB-related disorders: 1) callose plugging in phloem; 2) excessive starch accumulation in citrus leaves; and 3) excessive leaf and fruit drop. Citrus trees will be inoculated with CTV by grafting buds from trees infected with the CTV vector carrying the antisense RNA. Non-antisense CTV inoculated trees will be produced for comparisons. Following confirmation of infection with the viral vector, leaf extracts will be prepared and assayed for callose synthase activity, UDPG pyrophosphorylase, endoglucanase and polygalacturonase. Trees will subsequently be graft inoculated with CLas and the same assays will be used to determine if RNAi inhibition of the selected genes reduces Huanglongbing Disease (HLB) disease symptoms (callose plugging, excessive starch and abscission.