1a. Objectives (from AD-416):
Ethylene is an essential hormonal signal for soybean leaf and flower abscission and nematode infection of roots. In addition, other hormones, e.g., auxin, and peptide signals, e.g., IDA, modulate the plants response to ethylene. Gene expression and proteins involved in developmental mechanisms associated with abscission and nematode colonization of roots will be identified and characterized. The goal is to better understand shared signaling paths in soybean in order to genetically engineer soybean with higher productivity and improved resistance to nematode infection.
1b. Approach (from AD-416):
Several experimental approaches including RNA sequencing and proteomics will be used to identify genes and proteins linked to abscission and nematode infection. Their functional role in these processes will be determined by over-expression and suppression of selected genes in transgenic plants. Transformation protocols include viral induced gene silencing (VIGS), transformation and regeneration of mature plants, and hairy root transformation of axenic roots maintained on culture media.
3. Progress Report:
We prepared gene constructs (viral induced gene silencing, VIGS, constructs) designed to inhibit 3 soybean genes with similarity to a gene in Arabidopsis (IDA) that is proposed to control cell wall degradation during flower petal drop. We conducted preliminary experiments to examine the effect of these gene constructs on leaf abscission (leaf separation) in soybean. Unfortunately, disease symptoms from the virus were too great to draw reliable conclusions. Plants were recently transformed with a milder version of the viral constructs. Previously, we identified a root-knot nematode (plant pathogen) gene with similarity to the plant IDA gene. We prepared gene constructs designed to determine the function of the root-knot nematode IDA in the infection of plant roots.