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Marker Assisted Transfer of Two Powdery Mildew Resistance Genes PmTb7A.1 and PmTb7A.2 from Triticum boeoticum (Boiss.) to Triticum aestivum (L.).

Elkot AF, Chhuneja P, Kaur S, Saluja M, Keller B, Singh K - PLoS ONE (2015)

Bottom Line: The resulting F1s of the cross T. durum/T. boeoticum//T. aestivum were screened with marker flanking both the PM resistance genes PmTb7A.1 and PmTb7A.2 (foreground selection) and the selected plants were backcrossed to generate BC1F1.These will be crossed to generate lines combining both the PM resistance genes but with minimal of the alien introgression.Analysis of selected plants with markers linked to Sr22 showed introgression of Sr22 from T. boeoticum in several BC2F1 plants.

View Article: PubMed Central - PubMed

Affiliation: School of Agricultural Biotechnology, Punjab Agricultural University, Ludhiana, 141 004, India.

ABSTRACT
Powdery mildew (PM), caused by Blumeria graminis f. sp. tritici, is one of the important wheat diseases, worldwide. Two PM resistance genes, designated as PmTb7A.1 and PmTb7A.2, were identified in T. boeoticum acc. pau5088 and mapped on chromosome 7AL approximately 48cM apart. Two resistance gene analogue (RGA)-STS markers Ta7AL-4556232 and 7AL-4426363 were identified to be linked to the PmTb7A.1 and PmTb7A.2, at a distance of 0.6cM and 6.0cM, respectively. In the present study, following marker assisted selection (MAS), the two genes were transferred to T. aestivum using T. durum as bridging species. As many as 12,317 florets of F1 of the cross T. durum /T. boeoticum were pollinated with T. aestivum lines PBW343-IL and PBW621 to produce 61 and 65 seeds, respectively, of three-way F1. The resulting F1s of the cross T. durum/T. boeoticum//T. aestivum were screened with marker flanking both the PM resistance genes PmTb7A.1 and PmTb7A.2 (foreground selection) and the selected plants were backcrossed to generate BC1F1. Marker assisted selection was carried both in BC1F1 and the BC2F1 generations. Introgression of alien chromatin in BC2F1 plants varied from 15.4-62.9 percent. Out of more than 110 BC2F1 plants showing introgression for markers linked to the two PM resistance genes, 40 agronomically desirable plants were selected for background selection for the carrier chromosome to identify the plants with minimum of the alien introgression. Cytological analysis showed that most plants have chromosome number ranging from 40-42. The BC2F2 plants homozygous for the two genes have been identified. These will be crossed to generate lines combining both the PM resistance genes but with minimal of the alien introgression. The PM resistance gene PmTb7A.1 maps in a region very close to Sr22, a stem rust resistance gene effective against the race Ug99. Analysis of selected plants with markers linked to Sr22 showed introgression of Sr22 from T. boeoticum in several BC2F1 plants. Thus, in addition to PM resistance, these progeny might also carry resistance to stem rust race Ug99.

No MeSH data available.


Related in: MedlinePlus

Schematic representation of the crossing strategy adopted for transferring powdery mildew resistance genes from T. boeoticum to hexaploid wheat T. aestivum cv. PBW343-IL and PBW621 using durum wheat as bridging species.
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pone.0128297.g001: Schematic representation of the crossing strategy adopted for transferring powdery mildew resistance genes from T. boeoticum to hexaploid wheat T. aestivum cv. PBW343-IL and PBW621 using durum wheat as bridging species.

Mentions: The PM resistant T. boeoticum acc 5088 (2n = 14, AbAb) was crossed as male to T. durum cv PBW114 (2n = 28, AABB). The F1 plants (2n = 21, AbAB) were crossed to hexaploid wheat genotypes PBW343-IL and PBW621 (2n = 42, AABBDD). The triploid F1 plants have both male as well as female sterility and only those gametes are viable which have near complete A and B genome chromosome complement [40]. Nearly 7000 florets of the F1 of the cross T. durum cv PBW 114/T. boeoticum pau5088 were pollinated with PBW 343-IL and 5300 florets pollinated with PBW621 and only 61 (0.87%) seeds were obtained after crossing with PBW343-IL and 65 (1.22%) seeds with PBW 621. resulting complex F1 plants primarily pentaploids (2n = 35, AABBD) have a D genome from hexaploid wheat, the B genome from both tetraploid and hexaploid wheat and the A genome from all the three species (Fig 1). These pentaploid F1 plants were expected to segregate for the target trait; PM resistance. The pentaploid F1 plants were analyzed with the markers flanking the PM resistance genes. The plants having introgression from T. boeoticum for the target markers were identified and backcrossed to hexaploid recurrent parent (RP). The selected BC1F1 progeny were planted during off-season at Keylong, Himachal Pradesh, India. These progeny were having varying chromosome number, ranging from 35–42, with modal class of 40–42. The BC1F1 plants were backcrossed to the RP to generate BC2F1, which were selfed to produce BC2F2 families from which homozygous resistant plants were selected (Fig 1).


Marker Assisted Transfer of Two Powdery Mildew Resistance Genes PmTb7A.1 and PmTb7A.2 from Triticum boeoticum (Boiss.) to Triticum aestivum (L.).

Elkot AF, Chhuneja P, Kaur S, Saluja M, Keller B, Singh K - PLoS ONE (2015)

Schematic representation of the crossing strategy adopted for transferring powdery mildew resistance genes from T. boeoticum to hexaploid wheat T. aestivum cv. PBW343-IL and PBW621 using durum wheat as bridging species.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4466026&req=5

pone.0128297.g001: Schematic representation of the crossing strategy adopted for transferring powdery mildew resistance genes from T. boeoticum to hexaploid wheat T. aestivum cv. PBW343-IL and PBW621 using durum wheat as bridging species.
Mentions: The PM resistant T. boeoticum acc 5088 (2n = 14, AbAb) was crossed as male to T. durum cv PBW114 (2n = 28, AABB). The F1 plants (2n = 21, AbAB) were crossed to hexaploid wheat genotypes PBW343-IL and PBW621 (2n = 42, AABBDD). The triploid F1 plants have both male as well as female sterility and only those gametes are viable which have near complete A and B genome chromosome complement [40]. Nearly 7000 florets of the F1 of the cross T. durum cv PBW 114/T. boeoticum pau5088 were pollinated with PBW 343-IL and 5300 florets pollinated with PBW621 and only 61 (0.87%) seeds were obtained after crossing with PBW343-IL and 65 (1.22%) seeds with PBW 621. resulting complex F1 plants primarily pentaploids (2n = 35, AABBD) have a D genome from hexaploid wheat, the B genome from both tetraploid and hexaploid wheat and the A genome from all the three species (Fig 1). These pentaploid F1 plants were expected to segregate for the target trait; PM resistance. The pentaploid F1 plants were analyzed with the markers flanking the PM resistance genes. The plants having introgression from T. boeoticum for the target markers were identified and backcrossed to hexaploid recurrent parent (RP). The selected BC1F1 progeny were planted during off-season at Keylong, Himachal Pradesh, India. These progeny were having varying chromosome number, ranging from 35–42, with modal class of 40–42. The BC1F1 plants were backcrossed to the RP to generate BC2F1, which were selfed to produce BC2F2 families from which homozygous resistant plants were selected (Fig 1).

Bottom Line: The resulting F1s of the cross T. durum/T. boeoticum//T. aestivum were screened with marker flanking both the PM resistance genes PmTb7A.1 and PmTb7A.2 (foreground selection) and the selected plants were backcrossed to generate BC1F1.These will be crossed to generate lines combining both the PM resistance genes but with minimal of the alien introgression.Analysis of selected plants with markers linked to Sr22 showed introgression of Sr22 from T. boeoticum in several BC2F1 plants.

View Article: PubMed Central - PubMed

Affiliation: School of Agricultural Biotechnology, Punjab Agricultural University, Ludhiana, 141 004, India.

ABSTRACT
Powdery mildew (PM), caused by Blumeria graminis f. sp. tritici, is one of the important wheat diseases, worldwide. Two PM resistance genes, designated as PmTb7A.1 and PmTb7A.2, were identified in T. boeoticum acc. pau5088 and mapped on chromosome 7AL approximately 48cM apart. Two resistance gene analogue (RGA)-STS markers Ta7AL-4556232 and 7AL-4426363 were identified to be linked to the PmTb7A.1 and PmTb7A.2, at a distance of 0.6cM and 6.0cM, respectively. In the present study, following marker assisted selection (MAS), the two genes were transferred to T. aestivum using T. durum as bridging species. As many as 12,317 florets of F1 of the cross T. durum /T. boeoticum were pollinated with T. aestivum lines PBW343-IL and PBW621 to produce 61 and 65 seeds, respectively, of three-way F1. The resulting F1s of the cross T. durum/T. boeoticum//T. aestivum were screened with marker flanking both the PM resistance genes PmTb7A.1 and PmTb7A.2 (foreground selection) and the selected plants were backcrossed to generate BC1F1. Marker assisted selection was carried both in BC1F1 and the BC2F1 generations. Introgression of alien chromatin in BC2F1 plants varied from 15.4-62.9 percent. Out of more than 110 BC2F1 plants showing introgression for markers linked to the two PM resistance genes, 40 agronomically desirable plants were selected for background selection for the carrier chromosome to identify the plants with minimum of the alien introgression. Cytological analysis showed that most plants have chromosome number ranging from 40-42. The BC2F2 plants homozygous for the two genes have been identified. These will be crossed to generate lines combining both the PM resistance genes but with minimal of the alien introgression. The PM resistance gene PmTb7A.1 maps in a region very close to Sr22, a stem rust resistance gene effective against the race Ug99. Analysis of selected plants with markers linked to Sr22 showed introgression of Sr22 from T. boeoticum in several BC2F1 plants. Thus, in addition to PM resistance, these progeny might also carry resistance to stem rust race Ug99.

No MeSH data available.


Related in: MedlinePlus