Location: Temperate Tree Fruit and Vegetable Research
Project Number: 2092-22000-022-028-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: May 25, 2022
End Date: May 24, 2025
Objective:
Objective 1: Analyze feeding behavior and salivary gland transcriptomes of potato psyllid feeding from different host plants. We will test the hypotheses that a) gene expression plasticity allows psyllids to feed on different plant hosts, b) differences exist within both the genomes and transcriptomes of potato psyllid haplotypes, and c) Lso infection modifies psyllid feeding behavior and the salivary gland transcriptome.
Objective 2: Compare the expression of genes associated with previously identified effectors in different host plants. We will test the hypothesis that key candidate salivary gland genes are differentially expressed depending on the host plant and insect haplotype.
Objective 3: Evaluate the role of psyllid-secreted salivary proteins as “effectors” by expressing them in plants and evaluating effects on psyllid fitness.
Approach:
Objective 1: Lso-infected and uninfected potato psyllid adults of the northwestern or central haplotypes will be confined to potato, matrimony vine, or hairy nightshade. EPG: Feeding behavior of psyllids will be monitored using a four channel AC-DC EP monitor (Backus and Bennett 2009) following standard methodology for psyllids (Pearson et al. 2014). The total number of occurrences and mean duration of each waveform type representing different feeding and probing behaviors will be quantified and analyzed among combinations of psyllid haplotype, host plant, and Lso infection state. Transcriptome analysis: Salivary glands will be dissected from potato psyllids using methods developed by co-PIs Cooper and Tamborindeguy. The salivary glands will be pooled (at least 100 pairs) in RNALater and used for RNA purification. Three replicates per treatment will be sequenced and analyzed using methods optimized and routinely used by co-PI Tamborindeguy. We will sequence transcriptomes of potato psyllids which fed on potato and matrimony vine in year 1, reserving those which fed on hairy nightshade for sequencing in year 2.
Objective 2. Expression of secreted salivary protein genes that were previously identified by co-PI Tamborindeguy will be compared using real-time quantitative PCR among Lso-infected and uninfected psyllids of the northwestern and central haplotypes after feeding on potato, matrimony vine, and hairy nightshade. We expect to identify differences in the expression of key candidates depending on the host plant and insect haplotype.
Objective 3: We will transiently express candidate effectors in Nicotiana tabacum. Three to 5 days later, we will allow psyllids (adults and nymphs) to feed on the inoculated leaves. We will evaluate the effect of the effector in psyllid fitness as described in Xu et al. (2019).
