Investigating Non-Photochemical Quenching

Cailin Smith Author

07/27/2020 Added

141 Plays

Description

Poster presentation about research done during summer 2020 about non-photochemical quenching.

Searchable Transcript

Search:

[00:00:00.706]Hello, my name is Cailin Smith
[00:00:02.446]and this presentation is about
[00:00:04.103]investigating non-photochemical quenching.
[00:00:06.860]I will be presenting on 3 distinct
[00:00:08.688]projects, each at a different level of
[00:00:10.561]completion, yet all relating to the
[00:00:12.382]applications of improving non-photochemical
[00:00:14.631]quenching and photosynthesis.
[00:00:17.121]First, I will introduce the chloroplast
[00:00:18.882]project. Non-photochemical quenching,
[00:00:21.156]which I will now refer to as NPQ,
[00:00:23.107]is the mechanism plants use to protect
[00:00:25.206]themselves from high light intensity
[00:00:26.921]by redirecting solar energy into heat.
[00:00:29.673]The efficiency of NPQ is dependent upon
[00:00:32.000]the size and shape of the chloroplast,
[00:00:33.787]which is determined by the rate of
[00:00:35.324]plastid division.
[00:00:37.848]This figure depicts the proteins
[00:00:39.477]involved in the plastid ring division
[00:00:41.272]complex of land plants. I want to
[00:00:43.287]draw special attention to the proteins
[00:00:44.866]FtsZ and PDV1 and 2.
[00:00:49.628]In transgenic plants, perturbation of the
[00:00:52.017]levels of FtsZ and PDV results in
[00:00:54.680]plastid division defects and abnormal
[00:00:57.405]chloroplast size. For the chloroplast
[00:00:59.557]project, Arabidopsis FtsZ and S. lycopersicum
[00:01:03.012]PDV were overexpressed in transgenic
[00:01:05.570]N. tabacum in order to investigate
[00:01:07.225]how the manipulation of chloroplast size
[00:01:09.281]may improve NPQ and therefore photosynthesis.
[00:01:13.774]Cells from 4 transgenic lines of N. tabacum
[00:01:15.889]and corresponding wild types were all
[00:01:17.943]imaged using the same microscope. However,
[00:01:20.325]the chloroplasts within the images had to
[00:01:22.276]be analyzed using 2 different approaches,
[00:01:24.198]as summarized in table 1.
[00:01:26.585]Because the FtsZ mutants resulted in such
[00:01:28.880]large chloroplasts, those had to be
[00:01:30.939]measured by hand in a program called
[00:01:32.718]ImageJ. The PDV mutants and the wild type
[00:01:35.515]were all measured automatically using
[00:01:37.664]Weka Trainable Segmentation software.
[00:01:40.981]After analysis, the following results
[00:01:42.830]were elucidated.
[00:01:44.718]The overexpression of FtsZ resulted in
[00:01:47.143]much larger chloroplasts. Compared to the
[00:01:49.425]longest dimension in wild type, which is
[00:01:51.252]about 8, the longest dimension of the
[00:01:54.281]FtsZ mutants was about 2.6 times longer.
[00:01:58.207]The ratio of shortest-to-longest dimension
[00:02:00.480]is an indication of circularity, in which
[00:02:02.660]1 is a perfect circle. As for the PDV
[00:02:05.380]mutants, it was found that both PDV1 and
[00:02:08.317]PDV2 result in smaller chloroplasts, while
[00:02:11.570]the cross between PDV1 by PDV2 had the
[00:02:14.397]strongest effect on chloroplast size
[00:02:16.953]all around.
[00:02:20.152]Now, I will shift to the gene mapping
[00:02:21.831]project by explaining the results
[00:02:23.684]of a genome wide association study,
[00:02:25.347]or GWAS.
[00:02:27.700]This table summarizes the results from
[00:02:29.461]two GWASs. Here, a significant association
[00:02:32.389]between single nucleotide polymorphisms,
[00:02:34.851]or SNPs, and NPQ kinetics were detected
[00:02:37.783]in both Zea mays, which was grown in
[00:02:39.647]nitrogen deficient soil and in controlled
[00:02:41.426]soil, and in Sorghum bicolor, which was
[00:02:44.003]grown in controlled soil.
[00:02:46.552]A SNP is a genetic marker, while the
[00:02:48.685]frequency indicates the minor allele
[00:02:50.401]frequency of that SNP in the population.
[00:02:53.332]In maize, the 2 candidate genes that
[00:02:55.344]stuck out from the GWAS are
[00:02:56.831]glutaredoxin, or GRXS1, and
[00:02:59.126]5-phosphomevalonate kinase, or PMK.
[00:03:03.105]In sorghum, the 2 candidates are the
[00:03:05.075]cofactor of complex C, or CCB4, and
[00:03:08.439]argonaute 101.
[00:03:11.140]I will now discuss the roles of the
[00:03:12.800]proteins that are the products of the
[00:03:14.310]candidate genes from the GWAS.
[00:03:17.499]GRXS1 is a CC-type glutaredoxin, or GRX,
[00:03:21.536]and is specifically responsive to plant
[00:03:23.560]nitrate status. It acts as a negative
[00:03:25.895]regulator of vertical root growth
[00:03:27.588]in response to nitrogen, as seen here.
[00:03:31.534]PMK is an enzyme of the mevalonate
[00:03:33.479]pathway, which produces isoprenoids.
[00:03:35.969]Note that xanthophyll and chlorophyll
[00:03:37.757]are both isoprenoids, and are especially
[00:03:39.786]important to NPQ and photosynthesis.
[00:03:42.861]Another isoprenoid, cytokinin, is a plant
[00:03:45.788]hormone involved in cell signaling.
[00:03:49.384]CCB4 is a subunit of the cytochrome b6f
[00:03:52.401]complex, which is a major step in the
[00:03:54.573]electron transport chain in chloroplasts.
[00:03:57.327]This figure depicts a simplified role of
[00:03:59.367]cytochrome b6f in the light reaction
[00:04:01.453]of photosynthesis. Studies have found
[00:04:03.810]that disrupting the CCB4 gene leads to
[00:04:06.436]photosynthesis impairment.
[00:04:09.208]Argonaute101 is the central protein
[00:04:11.822]of the RNA-induced silencing complex,
[00:04:14.232]and is characterized by its
[00:04:15.671]catalytic PIWI domain.
[00:04:19.080]Finally, I am brought to the phenotyping
[00:04:20.948]project, the purpose of which is to
[00:04:22.746]investigate how soil nitrogen levels
[00:04:24.615]affect the kinetics of NPQ in a diverse
[00:04:27.197]set of maize genotypes.
[00:04:29.389]So far in this project, leaf samples from
[00:04:31.759]1,680 individual plants have been collected.
[00:04:35.532]The fluorescence of each sample was
[00:04:37.028]recorded during a 10-minute period of
[00:04:38.862]high light in order to measure the
[00:04:40.458]kinetics of NPQ induction,
[00:04:42.179]followed by a 10-minute period of
[00:04:43.901]darkness in order to measure the kinetics
[00:04:45.739]of NPQ relaxation, the results of which
[00:04:48.511]can be visualized by this example graph
[00:04:50.616]of NPQ kinetics.
[00:04:53.724]Using this method, approximately 1,160,000
[00:04:57.566]individual data points have been obtained.
[00:04:59.841]The next step of this project will be
[00:05:01.454]to analyze the rates of NPQ across
[00:05:03.572]different levels of soil nitrogen in order
[00:05:05.822]to confirm the results of the GWAS
[00:05:07.476]from the gene mapping project.
[00:05:09.645]I would like to acknowledge that this work
[00:05:11.317]is supported by the National Science
[00:05:12.708]Foundation, EPSCoR, and the University of
[00:05:15.316]Nebraska-Lincoln Center for Root and
[00:05:17.269]Rhizobiome Innovation.
[00:05:18.951]Thank you for your attention, and
[00:05:20.367]I will now be taking any questions.

The screen size you are trying to search captions on is too small!

You can always jump over to MediaHub and check it out there.

Comments

0 Comments

Investigating Non-Photochemical Quenching

Description

Searchable Transcript

Comments icon comment

Related Channels

Comments