Biology subjects

Pazouki, L.

Publications and source records attributed to Pazouki, L..

4 recordsLinked to original sources

bioRxiv2025

Functional relocation of the maize chloroplast atpB gene to the nucleus restores photosynthetic competence to a gene-edited non-photosynthetic mutant

We present a novel approach to photosynthetic gene engineering in maize using a nuclear-encoded, chloroplast-targeted TALE-cytidine deaminase enzyme to create non-photosynthetic knockout mutants of the chloroplast rbcL gene. An off-target mutation in the adjacent atpB gene, encoding the {beta} subunit of ATP synthase, was consistently found in all edited lines, identified as pigment-deficient in tissue culture. These double mutants, carrying mutations in both genes, were purified to homoplasmy using unique leaf-base regeneration techniques. To test mutation complementation and identify the causal gene, nuclear transgenic lines expressing chloroplast-targeted RbcL and AtpB proteins were generated. The results show that nuclear expression of AtpB restores chlorophyll accumulation and supports wild-type growth in tissue culture.

plant biology↗

bioRxiv2022

Comparative Phenotyping of Two Commonly Used Chlamydomonas reinhardtii Background Strains: CC-1690 (21gr) and CC-5325 (the CLiP Mutant Library Background)

The unicellular green alga Chlamydomonas reinhardtii is an excellent model organism to investigate many essential cellular processes in photosynthetic eukaryotes. Two commonly used background strains of Chlamydomonas are CC-1690 and CC-5325. CC-1690, also called 21gr, has been used for the Chlamydomonas genome project and several transcriptome analyses. CC-5325 is the background strain for the Chlamydomonas Library Project (CLiP). Photosynthetic performance in CC-5325 has not been evaluated in comparison with CC-1690. Additionally, CC-5325 is often considered to be cell-wall deficient, although detailed analysis is missing. The circadian rhythms in CC-5325 are also unclear. To fill these knowledge gaps and facilitate the use of the CLiP mutant library for various screens, we performed phenotypic comparisons between CC-1690 and CC-5325. Our results showed that CC-5325 grew faster heterotrophically in dark and equally well in mixotrophic liquid medium as compared to CC-1690. CC-5325 had lower photosynthetic efficiency and was more sensitive to heat than CC-1690. Furthermore, CC-5325 had an intact cell wall with comparable integrity to that in CC-1690, though appears to have reduced thickness. Finally, CC-5325 could perform phototaxis, but could not maintain a sustained circadian rhythm of phototaxis as CC160 did. Our results will be useful for researchers in the Chlamydomonas community to choose suitable background strains for mutant analysis and employ the CLiP mutant library for genome-wide mutant screens under appropriate conditions, especially in the areas of photosynthesis, thermotolerance, cell wall, and circadian rhythms.

plant biology↗

bioRxiv2021

Systems-wide Analysis Revealed Shared and Unique Responses to Moderate and Acute High Temperatures in the Green Alga Chlamydomonas reinhardtii

Different intensities of high temperatures affect the growth of photosynthetic cells in nature. To elucidate the underlying mechanisms, we cultivated the unicellular green alga Chlamydomonas reinhardtii under highly controlled photobioreactor conditions and revealed systems-wide shared and unique responses to 24-hour moderate (35{degrees}C) and acute (40{degrees}C) high temperatures and subsequent recovery at 25{degrees}C. We identified previously overlooked unique elements in response to moderate high temperature. Heat at 35{degrees}C transiently arrested the cell cycle followed by partial synchronization, up-regulated transcripts/proteins involved in gluconeogenesis/glyoxylate-cycle for carbon uptake, promoted growth, and increased starch accumulation. Heat at 40{degrees}C arrested the cell cycle, inhibited growth, resulting in carbon uptake over usage and increased starch accumulation. Both high temperatures induced photoprotection, while 40{degrees}C decreased photosynthetic efficiency, distorted thylakoid/pyrenoid ultrastructure, and affected the carbon concentrating mechanism. We demonstrated increased transcript/protein correlation during both heat treatments, suggesting reduced post-transcriptional regulation during heat may help coordinate heat tolerance activities efficiently. During recovery after both heat treatments, transcripts/proteins related to DNA synthesis increased while those involved in photosynthetic light reactions decreased. We propose down-regulating photosynthetic light reactions during DNA replication benefits cell cycle resumption by reducing ROS production. Our results provide potential targets to increase thermotolerance in algae and crops.

cell biology↗

bioRxiv2019

Plant seeds are primed by herbivore-induced plant volatiles

Mature plants can detect and respond to herbivore-induced plant volatiles (HIPVs) by priming or directly activating defenses against future herbivores. Whether other plant life stages can respond to HIPVs in similar manners is poorly understood. For example, seeds are known to respond to a variety of environment cues that are essential for proper germination timing and survival. Seeds may also be exposed to HIPVs prior to germination, and such exposure may affect the growth, development, and defense profiles when the seeds grow into mature plants. Here, we investigated the effect of seed exposure to common HIPVs on growth, reproduction and defense characteristics in the model plants Arabidopsis thaliana and Medicago truncatula. Of all the HIPVs tested, indole specifically reduced both beet armyworm growth on A. thaliana and pea 33 aphid fecundity on M. truncatula. Induction of defense genes was not affected by seed exposure to indole in either plant species, suggesting that seed priming operates independently of induced resistance. Moreover, neither species showed any negative effect of seed exposure to HIPVs on vegetative and reproductive growth. Rather, M. truncatula plants derived from seeds exposed to z-3-hexanol and z-3-hexenyl acetate grew faster and produced larger leaves compared to controls. Our results indicate that seeds are sensitive to specific HIPVs, which represents a novel ecological mechanism of plant-to-plant communication.

plant biology↗