Impact of Induced Sorghum Defense Mechanisms on Aphid Reproduction

Jessica Ayala Author

07/28/2021 Added

13 Plays

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Nebraska Virtual Summer Research Symposium 2021. “ Impact of Induced Sorghum Defense Mechanisms on Aphid Reproduction.”

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[00:00:01.110]Hello.
[00:00:01.980]My name is Jessica Ayala and my poster is on the impact of induced sorghum
[00:00:06.510]defense mechanisms on aphid reproduction. To start- sorghum is a
[00:00:11.460]widely used cereal crop that is severely impacted by aphid infestation.
[00:00:16.170]Aphids feed on sorghum via a stylet,
[00:00:18.390]that they use to pierce the plant tissue and manipulate to circumvent other cells
[00:00:22.710]In order to reach the phloem.
[00:00:24.940]Aphids try to do as little damage to the plant as possible in order to avoid
[00:00:28.920]inciting a defense response in the plant,
[00:00:31.350]which can increase their resistance to insect attacks. the objectives of this
[00:00:36.270]study,
[00:00:36.870]are to determine the effects of sequential aphid attacks on sorghum
[00:00:40.710]plants,
[00:00:41.160]as well as to understand the differential defense responses in sorghum
[00:00:44.910]following sugarcane aphid and Greenbug attacks. Sequential
[00:00:49.740]herbivory is an important factor in this study because while most research
[00:00:53.160]studies focus on the effect of a specific insect in, the field
[00:00:57.060]plants are subject to predation from multiple species of insects
[00:01:01.170]at a time. My research was divided into two experimental methods,
[00:01:06.030]a bioassay and gene expression studies. For the bioassay
[00:01:10.090]I had four experimental groups: control, sugarcane aphids, control
[00:01:14.230]green bugs, and green bugs to sugarcane aphids and sugarcane
[00:01:18.150]aphids to green bugs.
[00:01:20.190]Each group was infested with either 10 sugarcane aphids or 10 green bugs,
[00:01:24.450]which were then removed after 48 hours and re-infested with the other species of
[00:01:28.770]aphid. After 96 hours,
[00:01:31.710]the remaining aphids were counted on each plant. For the gene
[00:01:36.510]expression studies
[00:01:37.440]We collected samples from plants that had been infested with either sugarcane,
[00:01:40.890]aphids or green bugs for a 48 hour period.
[00:01:45.390]We use samples from un-infested plants as the control group. We performed RNA
[00:01:50.160]extraction followed by cDNA synthesis,
[00:01:52.980]and then analyze the samples using QRT PCR. For
[00:01:57.300]QRT PCR,
[00:01:58.920]we use a housekeeping primer, tubulin, and compared it to the pathogenesis
[00:02:02.940]related target genes, PR1 and PR10.
[00:02:06.930]The reason we used pathogenic related target genes is because they code for
[00:02:10.500]salycilic acid.
[00:02:12.420]Salycilic acid is more indicative of aphid responses in plants because plants
[00:02:17.250]treat aphids as a pathogen rather than an external threat,
[00:02:20.850]such as a caterpillar.
[00:02:23.430]The results from the bioassay indicate that green bug infested sorghum plants
[00:02:27.900]are more resistant to sugarcane aphids. Figure one B
[00:02:32.730]illustrates that the number of sugarcane aphids found after green bug pre
[00:02:36.240]infestation is significantly lower than the number of sugarcane aphids found
[00:02:40.740]on the control plants.
[00:02:42.480]Comparatively figure one D indicates that there is no significant difference
[00:02:46.890]between the number of green bugs on sugarcane aphid pre infested plants,
[00:02:51.300]and the control plants. The results from
[00:02:54.690]The gene expression studies indicate that green bugs induced stronger defense
[00:02:59.380]responses in sorghum plants than sugar cane aphids figure two A shows that
[00:03:03.970]there is a significant difference between the salycilic acid produced between
[00:03:08.140]the control sugarcane aphids and green bugs. Here
[00:03:12.070]We see that PR one expression is actually lower in sugarcane
[00:03:15.490]aphids than in the control,
[00:03:17.200]which means that sugarcane aphids are able to suppress the defense response in
[00:03:21.460]sorghum.
[00:03:22.570]We can also see that green bugs induce a significantly stronger defense
[00:03:26.920]response in sorghum,
[00:03:28.360]about 81 times stronger in fact. Figure two B
[00:03:32.830]illustrates that there is also a significant difference in the expression of the
[00:03:36.250]PR 10 gene. Here,
[00:03:38.770]we can see the green bugs still induce a stronger defense response than sugarcane
[00:03:42.670]aphids do by about twenty-five times. From these results,
[00:03:47.290]we can conclude that green bug infested plants provide enhanced resistance to
[00:03:51.880]sugarcane aphid infestations,
[00:03:54.430]as well as that sugarcane infested plants,
[00:04:00.700]support similar numbers of green bug aphids as undamaged plants.
[00:04:05.740]We can also conclude that the expression level of salycilic acid marker
[00:04:10.630]genes PR one and PR10 are 81 and 25 times
[00:04:15.160]stronger respectively in green bug infested plants compared to sugar
[00:04:20.050]cane aphid infested the plants.
[00:04:22.630]The significance of these studies is that it aids in the designing
[00:04:27.550]aphid resistant crops.
[00:04:29.470]It reduces the need for chemical applications on crops,
[00:04:32.890]as well as contributes to sustainable sorghum pest management strategies.
[00:04:37.960]Future prospects of these studies could be to determine the difference
[00:04:41.200]between sugar cane aphids and green bug aphid salivary components,
[00:04:45.340]as well as to further explore the other underlying molecular and biochemical
[00:04:49.300]defense mechanisms to insects.
[00:04:53.380]I also want to acknowledge that this research was supported by the national
[00:04:56.590]science foundation CAREER grant awarded to Dr. Joe Lewis.
[00:05:00.910]And I want to thank you for listening to my presentation,
[00:05:03.250]and I hope you learned something. Thank you.

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Impact of Induced Sorghum Defense Mechanisms on Aphid Reproduction

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