Update:
Host-derived silencing for SCN:

Again this year we have field tests with our transgenic lines. Due to the wet spring, planting was delayed until the beginning of June. At the end of the funding cycle we observed germination and plant growth in all of our entries. SCN counts are planned for mid-July.

We have conducted crossing and backcrossing from the RNAi transgenic lines to two Kansas cultivars: K11-2363B and K12-2333, respectively. So far we have done three rounds crossing and one round backcrossing. The F2 seeds from crossing events (Prp17 X K11, Prp17 X K12, and Y25 X K12) have been increased and harvested. For K11XY25 and stacking two RNAi constructs (Y25 X Prp17, and Prp17 X Y25) into one transgenic line, we only have some F1 seeds ready, and need to be tested. Seeds availability is shown in the following table.

K11-2363B (mild resistance to SCN HG type7) and K12-2333 (mild tolerance)
Crossing (Female X pollinator) = Crossing results
K11 X Y25 = More F1 seeds to test
K11X Prp17 = F2 available
K12 X Y25 = F2 available
K12X Prp17 = F2 available
Y25 X Prp17 = More F1 seeds to test
Prp17 X Y25 = More F1 seeds to test

We have done one round of backcross with either K11 or K12 as parent for positive F2 plants, and get some pods with seeds. We need to grow these seeds and PCR test if the backcross is successful or not.

Currently, we will continue to set up crossing and backcrossing assays with available seeds, and will try to set up some available seeds for SCN bioassays in the greenhouse. It is anticipated that these lines could be used in field tests next year.

Host-derived RNAi silencing for the stem borer in soybean:

Dectes texanus is an important pest on soybean crops. When feeding with medium containing In Vitro RNAi, D. texanus showed the symptoms with expected phenotypes. Therefore, we have constructed three RNAi vectors targeting three different bug genes. They have been used for stable transformation in soybean, and for expression in hairy roots, named p35HK-DtPilot, p35HK_DtChtn, and p35HK_DtCP8E2, respectively.

Some putative tissues from stable transformation have been developed and selected, and we are going to extract gDNA for PCR confirmation.

For hairy root systems, we had generated a few chimeric plants, but not enough for bioassay test. Currently, the summer intern undergrad student and I try to establish a new protocol for generating transgenic hairy roots for these three RNAi constructs.

Improving soybean drought tolerance through genetic engineering GmNAC (NAM, ATAF and CUC transcription factors) gene family:

From analyses of soybean GmNAC gene family related to drought tolerance, we had selected several candidates for genetic engineering. Currently, we are working on four candidates on the list: GmNAC004, GmNAC174, GmNAC177 and GmNAC021. The gene fragments of GmNAC174 and GmNAC177 have been cloned, and we are going to make RNAi constructs to knocking down these two genes by stable transformation as well as in chemic hairy root plants. Those transgenic chemic plants will be tested for drought tolerance improvement.