Location: Molecular Plant Pathology Laboratory
Project Number: 8042-21220-262-000-D
Project Type: In-House Appropriated
Start Date: Jun 21, 2023
End Date: Jun 20, 2028
Objective 1. Devise and develop advanced biotechnological approaches to address and improve SB pest and disease resistance, abiotic factors, yield, and quality. Objective 2. Decipher and understand molecular mechanisms of Sugarbeet root defense responses to pest and pathogen attack. Sub-objective 2A. Perform gene expression in SB to identify genes that relate to SB disease response. Sub-objective 2B. Perform gene expression studies in related systems that relate to the SB systems.
Sugar beet root defense genes incited by the root maggot, a destructive pest of sugar beet, will be functionally characterized in sugar beet and Nicotiana using molecular transformation approaches and genome editing (CRISPR-Cas9).Understanding of the genes’ role in defense will be used to develop screening protocols of sugar beet germplasm for resistance traits and to devise novel strategies for pest and disease control. The role of two genes that were demonstrated to enhance resistance and that preferentially respond to root maggot feeding in a resistant germplasm will be evaluated for resistance to insects and phytopathogens. Genetically modified sugar beet roots and Nicotiana plants that were demonstrated to be resistant to several different insects will be bioassayed for resistance to sugar beet fungal pathogens, and conversely modified plants that were shown to be resistant to several phytopathogens will be screened for resistance to insect pests. One of the sugar beet genes that codes for a serine proteinase inhibitor (PI; BvSTI) was shown to enhance resistance to several insect pests (beet and fall armyworm, tobacco hornworm). Another sugar beet gene that codes for a cell wall polygalacturonase inhibitor (PGIP, BvPGIP) was shown to enhance fungal resistance to Fusarium solani, Rhizoctonia solani and Botrytis cinerea. BvSTI is a wound inducible serine PI with specificity for the root maggot digestive enzymes that mediate release of nutrients from ingested plant tissues. BvPGIP codes for a leucine-rich repeat glycoprotein PGIP that is associated with cell wall structure and plant defense responses. A group of sugar beet genes encoding enzymes for fatty acid (lipid) biosynthesis were also isolated using a transcriptomic approach and shown to increase lipid accumulation by up to 45% in sugar beet roots and Nicotiana plants. To evaluate the effect of elevated lipids on resistance, plants producing the recombinant fatty acid transcription factors will be bioassayed for insect and fungal resistance using similar approaches as described above. To more precisely target the expression of beneficial genes to root cells and tissues most prone to pest and pathogen attack, BvPGIP and BvSTI gene promoters will be characterized in sugar beet hairy roots and model plants. Expression of a GUS reporter gene fused to the sugar beet promoters will be evaluated in response to various biotic and abiotic stresses that include insect infestation, phytopathogen infection and mechanical wounding. In complementary studies of insect responses, root maggot genes that were shown to be important for interaction of the pest with resistant or susceptible sugar beet roots will be characterized. Profiled, sequenced and functionally annotated root maggot genes will provide new knowledge of how insects adapt to host plants and surmount host resistance. With the newly discovered knowledge of sugar beet resistance and root maggot genes, genome editing approaches will be designed to improve plant resistance. Identified pest and root these genes will also be used to screen elite sugar beet germplasm for inherent resistance traits.