Browsing by Author "Qi, Xing"

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Phosphorus deficiency alleviates iron limitation in Synechocystis cyanobacteria through direct PhoB-mediated gene regulation
(2024) Qiu, Guo Wei; Zheng, Wen Can; Yang, Hao Ming; Wang, Yu Ying; Qi, Xing; Huang, Da; Dai, Guo Zheng; Shi, Huazhong (TTU); Price, Neil M.; Qiu, Bao Sheng
Iron and phosphorus are essential nutrients that exist at low concentrations in surface waters and may be co-limiting resources for phytoplankton growth. Here, we show that phosphorus deficiency increases the growth of iron-limited cyanobacteria (Synechocystis sp. PCC 6803) through a PhoB-mediated regulatory network. We find that PhoB, in addition to its well-recognized role in controlling phosphate homeostasis, also regulates key metabolic processes crucial for iron-limited cyanobacteria, including ROS detoxification and iron uptake. Transcript abundances of PhoB-targeted genes are enriched in samples from phosphorus-depleted seawater, and a conserved PhoB-binding site is widely present in the promoters of the target genes, suggesting that the PhoB-mediated regulation may be highly conserved. Our findings provide molecular insights into the responses of cyanobacteria to simultaneous iron/phosphorus nutrient limitation.
Transposon mutagenesis for cotton functional genomics
(2014-05) Qi, Xing; Wright, Robert J.; Zhang, Hong; Auld, Dick L.; Paré, Paul W.; Burow, Mark D.
To enable better reverse genetic strategies in cotton (Gossypium spp.) the creation of artificial mutations by transposon mutagenesis was investigated. The Dslox transposable element system is an enabling technology that combines the advantages of transposon-tagging using the maize Ac/Ds system to produce insertion mutants, but it also includes a lox sequence in the Ds element and another strategically placed upstream but within the T-DNA. This creates the opportunity to induce gross chromosomal rearrangements or deletions within the region flanked by the lox sites. The Dslox mutagenesis strategy gives us an unprecedented opportunity to unveil gene functions important to agronomic traits. Approximately 150 Dslox transgenic cotton (Gossypium hirsutum L.cv. Coker 312-317) lines, two Ac lines and one Cre line have been produced. Those Dslox and Ac lines were characterized at the molecular level to permit sorting into single full insertion lines. Results showed that higher than expected numbers of partial Dslox insertion events were produced. The poor recovery of full length Dslox events suggest that some factor(s) such as instability of the inserted T-DNA (event) or exceeding the physical size limits for efficient transformation are important. The Gossypium genome contains evidence of numerous transposable elements, so an endogenous mechanism leading to the transposition of Dslox without Ac would not be unexpected. Instability of the T-DNA insertion of subsequent inheritance is possible but would have occurred at a much higher rate than in other transformation projects in cotton. The large size of the Dslox T-DNA (11.9 Kb) may have exceeded the physical limits for efficient transformation in cotton.