Cloning, mutagenesis, and characterization of the microalga Parietochloris incisa acetohydroxyacid synthase, and its possible use as an endogenous selection marker

The use of herbicides is an effective and economic way to control weeds, but their availability for rapeseed is limited due to the shortage of herbicide-resistant cultivars in China. The single-point mutation in the acetohydroxyacid synthase (AHAS) gene can lead to AHAS-inhibiting herbicide resistance. In this study, the inheritance and molecular characterization of the tribenuron-methyl (TBM)-resistant rapeseed (Brassica napus L.) mutant, K5, are performed. Results indicated that TBM-resistance of K5 was controlled by one dominant allele at a single nuclear gene locus. The novel substitution of cytosine with thymine at position 544 in BnAHAS1 was identified in K5, leading to the alteration of proline with serine at position 182 in BnAHAS1. The TBM-resistance of K5 was approximately 100 times that of its wild-type ZS9, and K5 also showed cross-resistance to bensufuron-methyl and monosulfuron-ester sodium. The BnAHAS1544T transgenic Arabidopsis exhibited higher TBM-resistance than that of its wild-type, which confirmed that BnAHAS1544T was responsible for the herbicide resistance of K5. Simultaneously, an allele-specific marker was developed to quickly distinguish the heterozygous and homozygous mutated alleles BnAHAS1544T. In addition, a method for the fast screening of TBM-resistant plants at the cotyledon stage was developed. Our research identified and molecularly characterized one novel mutative AHAS allele in B. napus and laid a foundation for developing herbicide-resistant rapeseed cultivars.

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Development of a Simvastatin Selection Marker for a Hyperthermophilic Acidophile, Sulfolobus islandicus

Applied and Environmental Microbiology ◽

10.1128/aem.06095-11 ◽

2011 ◽

Vol 78 (2) ◽

pp. 568-574 ◽

Cited By ~ 33

Author(s):

Tao Zheng ◽

Qihong Huang ◽

Changyi Zhang ◽

Jinfeng Ni ◽

Qunxin She ◽

...

Keyword(s):

Selectable Marker ◽

Gene Knockout ◽

Plasmid Vector ◽

Selection Marker ◽

Content Type ◽

Sulfolobus Islandicus ◽

Gene Coding ◽

High Level ◽

Coa Reductase

ABSTRACTWe report here a novel selectable marker for the hyperthermophilic crenarchaeonSulfolobus islandicus. The marker cassette is composed of thesac7dpromoter and thehmggene coding for the 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase (Psac7d-hmg), which confers simvastatin resistance to this crenarchaeon. The basic plasmid vector pSSR was constructed by substituting thepyrEFgene of the expression vector pSeSD for Psac7d-hmgwith which theSulfolobusexpression plasmids pSSRlacS, pSSRAherA, and pSSRNherA were constructed. Characterization ofSulfolobustransformants carrying pSSRlacS indicated that the plasmid was properly maintained under selection. High-level expression of the His6-tagged HerA helicase was obtained with the cells harboring pSSRAherA. The establishment of two efficient selectable markers (pyrEFandhmg) was subsequently exploited for genetic analysis. AherAmerodiploid strain ofS. islandicuswas constructed usingpyrEFmarker and used as the host to obtain pSSRNherA transformant with simvastatin selection. While the gene knockout (ΔherA) cells generated from theherAmerodiploid cells failed to form colonies in the presence of 5-fluoroorotic acid (5-FOA), the mutant cells could be rescued by expression of the gene from a plasmid (pSSRNherA), because their transformants formed colonies on a solid medium containing 5-FOA and simvastatin. This demonstrates that HerA is essential for cell viability ofS. islandicus. To our knowledge, this is the first application of an antibiotic selectable marker in genetic study for a hyperthermophilic acidophile and in the crenarchaeal lineage.

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