Construction of a bacterial artificial chromosome (BAC) library for citrus and identification of BAC contigs containing resistance gene candidates

2001 ◽  
Vol 102 (8) ◽  
pp. 1177-1184 ◽  
Author(s):  
Z. Deng ◽  
Q. Tao ◽  
Y.-L. Chang ◽  
S. Huang ◽  
P. Ling ◽  
...  
Genome ◽  
1997 ◽  
Vol 40 (4) ◽  
pp. 420-427 ◽  
Author(s):  
L. Fredrick Marek ◽  
R. C. Shoemaker

We constructed a soybean bacterial artificial chromosome (BAC) library suitable for map-based cloning and physical mapping in soybean. This library consists of approximately 40 000 clones (4–5 genome equivalents) stored individually in 384-well microtiter dishes. A random sampling of 224 clones yielded an average insert size of 150 kb, giving a 98% probability of recovering any specific sequence. We screened the library for seven single or very low copy genie or genomic sequences using the polymerase chain reaction (PCR) and found between one and seven BACs for each of the seven sequences. When testing the library with a portion of the soybean psbA chloroplast gene, we found less than 1% chloroplast DNA representation. We also screened the library for eight different classes of disease resistance gene analogs (RGAs) and identified BACs containing all RGAs except class 8. We arranged nine of the class 1 RGA BACs and six of the class 3 RGA BACs into individual contigs based on fingerprint patterns observed after Southern probing of restriction digests of the member BACs with a class-specific sequence. This resulted in the partial localization of the different multigene family sequences without precise definition of their exact positions. Using PCR-based end rescue techniques and RFLP mapping of BAC ends, we mapped individual BACs of each contig onto linkage group J of the soybean public map. The class 1 contig mapped to the region on linkage group J that contains several disease resistance genes. The class 1 contig extended approximately 400 kb. The arrangement of the BACs within this contig has been confirmed using PCR. One end of the class 1 contig core BAC mapped to two positions on linkage group J and cosegregated with two class 1 RGA loci, suggesting that this segment is within an area of regional duplication.Key words: bacterial artificial chromosome, BAC library, soybean, contig, resistance gene analog.


Gene ◽  
2002 ◽  
Vol 295 (2) ◽  
pp. 247-254 ◽  
Author(s):  
Alexander Froschauer ◽  
Cornelia Körting ◽  
Takayuki Katagiri ◽  
Takashi Aoki ◽  
Shuichi Asakawa ◽  
...  

Genome ◽  
2004 ◽  
Vol 47 (2) ◽  
pp. 239-245 ◽  
Author(s):  
Yaping Qian ◽  
Li Jin ◽  
Bing Su

The large-insert genomic DNA library is a critical resource for genome-wide genetic dissection of target species. We constructed a high-redundancy bacterial artificial chromosome (BAC) library of a New World monkey species, the black-handed spider monkey (Ateles geoffroyi). A total of 193 152 BAC clones were generated in this library. The average insert size of the BAC clones was estimated to be 184.6 kb with the small inserts (50-100 kb) accounting for less than 3% and the non-recombinant clones only 1.2%. Assuming a similar genome size with humans, the spider monkey BAC library has about 11× genome coverage. In addition, by end sequencing of randomly selected BAC clones, we generated 367 sequence tags for the library. When blasted against human genome, they showed a good correlation between the number of hit clones and the size of the chromosomes, an indication of unbiased chromosomal distribution of the library. This black-handed spider monkey BAC library would serve as a valuable resource in comparative genomic study and large-scale genome sequencing of nonhuman primates.Key words: black-handed spider monkeys, Ateles geoffroyi, BAC library.


Genome ◽  
2001 ◽  
Vol 44 (2) ◽  
pp. 154-162 ◽  
Author(s):  
Meizhong Luo ◽  
Yi-Hong Wang ◽  
David Frisch ◽  
Tarek Joobeur ◽  
Rod A Wing ◽  
...  

Utilizing improved methods, two bacterial artificial chromosome (BAC) libraries were constructed for the multidisease-resistant line of melon MR-1. The HindIII library consists of 177 microtiter plates in a 384-well format, while the EcoRI library consists of 222 microtiter plates. Approximately 95.6% of the HindIII library clones contain nuclear DNA inserts with an average size of 118 kb, providing a coverage of 15.4 genome equivalents. Similarly, 96% of the EcoRI library clones contain nuclear DNA inserts with an average size of 114 kb, providing a coverage of 18.7 genome equivalents. Both libraries were evaluated for contamination with high-copy vector, empty pIndigoBac536 vector, and organellar DNA sequences. High-density filters were screened with two genetic markers FM and AM that co-segregate with Fom-2, a gene conferring resistance to races 0 and 1 of Fusarium wilt. Fourteen and 18 candidate BAC clones were identified for the FM and AM probes, respectively, from the HindIII library, while 34 were identified for the AM probe from filters A, B, and C of the EcoRI library.Key words: bacterial artificial chromosome (BAC) library, Fusarium wilt, melon, pCUGIBAC1, resistant gene.


1998 ◽  
Vol 66 (5) ◽  
pp. 2221-2229 ◽  
Author(s):  
Roland Brosch ◽  
Stephen V. Gordon ◽  
Alain Billault ◽  
Thierry Garnier ◽  
Karin Eiglmeier ◽  
...  

ABSTRACT The bacterial artificial chromosome (BAC) cloning system is capable of stably propagating large, complex DNA inserts in Escherichia coli. As part of the Mycobacterium tuberculosis H37Rv genome sequencing project, a BAC library was constructed in the pBeloBAC11 vector and used for genome mapping, confirmation of sequence assembly, and sequencing. The library contains about 5,000 BAC clones, with inserts ranging in size from 25 to 104 kb, representing theoretically a 70-fold coverage of the M. tuberculosisgenome (4.4 Mb). A total of 840 sequences from the T7 and SP6 termini of 420 BACs were determined and compared to those of a partial genomic database. These sequences showed excellent correlation between the estimated sizes and positions of the BAC clones and the sizes and positions of previously sequenced cosmids and the resulting contigs. Many BAC clones represent linking clones between sequenced cosmids, allowing full coverage of the H37Rv chromosome, and they are now being shotgun sequenced in the framework of the H37Rv sequencing project. Also, no chimeric, deleted, or rearranged BAC clones were detected, which was of major importance for the correct mapping and assembly of the H37Rv sequence. The minimal overlapping set contains 68 unique BAC clones and spans the whole H37Rv chromosome with the exception of a single gap of ∼150 kb. As a postgenomic application, the canonical BAC set was used in a comparative study to reveal chromosomal polymorphisms between M. tuberculosis, M. bovis, and M. bovis BCG Pasteur, and a novel 12.7-kb segment present in M. tuberculosis but absent from M. bovis and M. bovis BCG was characterized. This region contains a set of genes whose products show low similarity to proteins involved in polysaccharide biosynthesis. The H37Rv BAC library therefore provides us with a powerful tool both for the generation and confirmation of sequence data as well as for comparative genomics and other postgenomic applications. It represents a major resource for present and future M. tuberculosis research projects.


1998 ◽  
Vol 10 (8) ◽  
pp. 671 ◽  
Author(s):  
Kurt A. Zuelke

The application of transgenic technologies in dairy cattle has been restricted largely to producing potential pharmaceutical or nutriceutical products in the mammary gland. Broader application of transgenesis in dairy cattle production will require identifying target traits that are both amenable to transgenic modification and economically important to the dairy industry. The casein proteins are the most valuable component of cows milk destined for value-added processing. The four bovine casein genes lie within a single, multi-gene locus of approximately 200 kb in length. The working hypothesis is that this multi-gene locus contains all of the DNA sequences required to regulate the coordinated expression of all four individual casein genes (i.e. a locus control region or LCR). The initial research aim is to clone the entire casein locus into a bacterial artificial chromosome (BAC) vector, thus preserving the extended 5′and 3′ regions that flank the locus, as well as maintaining the spatial integrity of the four individual casein genes that comprise the locus. The author's laboratory has prepared a bacterial artificial chromosome (BAC) library of genomic DNA from elite dairy cattle. Partial, non-elite BAC clones of the casein gene locus are being tested in transgenic mice to establish proof of concept. Advances in nuclear transfer of transfected somatic cells should improve the efficiency of producing transgenic calves that possess a BAC casein construct introduced into an elite genetic background.


Genome ◽  
2001 ◽  
Vol 44 (6) ◽  
pp. 1057-1064 ◽  
Author(s):  
K S Lewers ◽  
S D Nilmalgoda ◽  
A L Warner ◽  
H T Knap ◽  
B F Matthews

The soybean cyst nematode (SCN), Heterodera glycines Ichinohe, is the foremost pest of soybean (Glycine max L. Merr.). The rhg1 allele on linkage group (LG) G and the Rhg4 allele on LG A2 are important in conditioning resistance. Markers closely linked to the Rhg4 locus were used previously to screen a library of bacterial artificial chromosome (BAC) clones from susceptible 'Williams 82' and identified a single 150-kb BAC, Gm_ISb001_056_G02 (56G2). End-sequenced subclones positioned onto a restriction map provided landmarks for identifying the corresponding region from a BAC library from accession PI 437654 with broad resistance to SCN. Seventy-three PI 437654 BACs were assigned to contigs based upon HindIII restriction fragment profiles. Four contigs represented the PI 437654 counterpart of the 'Williams 82' BAC, with PCR assays connecting these contigs. Some of the markers on the PI 437654 contigs are separated by a greater physical distance than in the 'Williams 82' BAC and some primers amplify bands from BACs in the mid-portion of the connected PI 437654 BAC contigs that are not amplified from the 'Williams 82' BAC. These observations suggest that there is an insertion in the PI 437654 genome relative to the 'Williams 82' genome in the Rhg4 region.Key words: BAC, deletion, insertion, resistance gene, soybean cyst nematode.


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