A Physical Map of the 1-Gigabase Bread Wheat Chromosome 3B

Although most flowering plants are polyploid, little is known of how the meiotic process evolves after polyploidisation to stabilise and preserve fertility. On wheat polyploidisation, the major meiotic gene ZIP4 on chromosome 3B duplicated onto 5B and diverged (TaZIP4-B2). TaZIP4-B2 was recently shown to promote homologous pairing, synapsis and crossover, and suppress homoeologous crossover. We therefore suspected that these meiotic stabilising effects could be important for preserving wheat fertility. A CRISPR Tazip4-B2 mutant was exploited to assess the contribution of the 5B duplicated ZIP4 copy in maintaining pollen viability and grain setting. Analysis demonstrated abnormalities in 56% of meiocytes in the Tazip4-B2 mutant, with micronuclei in 50% of tetrads, reduced size in 48% of pollen grains and a near 50% reduction in grain number. Further studies showed that most of the reduced grain number occurred when Tazip4-B2 mutant plants were pollinated with the less viable Tazip4-B2 mutant pollen rather than with wild type pollen, suggesting that the stabilising effect of TaZIP4-B2 on meiosis has a greater consequence in subsequent male, rather than female gametogenesis. These studies reveal the extraordinary value of the wheat chromosome 5B TaZIP4-B2 duplication to agriculture and human nutrition. Future studies should further investigate the role of TaZIP4-B2 on female fertility and assess whether different TaZIP4-B2 alleles exhibit variable effects on meiotic stabilisation and/or resistance to temperature change.

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Cytogenetic analysis and mapping of leaf rust resistance in Aegilops speltoides Tausch derived bread wheat line Selection2427 carrying putative gametocidal gene(s)

Genome ◽

10.1139/gen-2017-0107 ◽

2017 ◽

Vol 60 (12) ◽

pp. 1076-1085 ◽

Cited By ~ 2

Author(s):

M. Niranjana ◽

Vinod ◽

J.B. Sharma ◽

Niharika Mallick ◽

S.M.S. Tomar ◽

...

Keyword(s):

Leaf Rust ◽

Bread Wheat ◽

Rust Resistance ◽

Dominant Gene ◽

Puccinia Triticina ◽

Leaf Rust Resistance ◽

Aegilops Speltoides ◽

Lr Genes ◽

Gametocidal Gene ◽

Chromosome 3B

Leaf rust (Puccinia triticina) is a major biotic stress affecting wheat yields worldwide. Host-plant resistance is the best method for controlling leaf rust. Aegilops speltoides is a good source of resistance against wheat rusts. To date, five Lr genes, Lr28, Lr35, Lr36, Lr47, and Lr51, have been transferred from Ae. speltoides to bread wheat. In Selection2427, a bread wheat introgresed line with Ae. speltoides as the donor parent, a dominant gene for leaf rust resistance was mapped to the long arm of chromosome 3B (LrS2427). None of the Lr genes introgressed from Ae. speltoides have been mapped to chromosome 3B. Since none of the designated seedling leaf rust resistance genes have been located on chromosome 3B, LrS2427 seems to be a novel gene. Selection2427 showed a unique property typical of gametocidal genes, that when crossed to other bread wheat cultivars, the F1 showed partial pollen sterility and poor seed setting, whilst Selection2427 showed reasonable male and female fertility. Accidental co-transfer of gametocidal genes with LrS2427 may have occurred in Selection2427. Though LrS2427 did not show any segregation distortion and assorted independently of putative gametocidal gene(s), its utilization will be difficult due to the selfish behavior of gametocidal genes.

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A Physical Map of the Short Arm of Wheat Chromosome 1A

PLoS ONE ◽

10.1371/journal.pone.0080272 ◽

2013 ◽

Vol 8 (11) ◽

pp. e80272 ◽

Cited By ~ 22

Author(s):

James Breen ◽

Thomas Wicker ◽

Margarita Shatalina ◽

Zeev Frenkel ◽

Isabelle Bertin ◽

...

Keyword(s):

Physical Map ◽

Wheat Chromosome

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A cytogenetically based physical map of chromosome 1B in common wheat

Genome ◽

10.1139/g93-075 ◽

1993 ◽

Vol 36 (3) ◽

pp. 548-554 ◽

Cited By ~ 51

Author(s):

R. S. Kota ◽

K. S. Gill ◽

B. S. Gill ◽

T. R. Endo

Keyword(s):

Genetic Markers ◽

Common Wheat ◽

Hexaploid Wheat ◽

Genetic Linkage ◽

Genetic Linkage Map ◽

Physical Map ◽

Wheat Chromosome ◽

Homozygous Deletion ◽

Genetic Maps ◽

Rflp Markers

We have constructed a cytogenetically based physical map of chromosome 1B in common wheat by utilizing a total of 18 homozygous deletion stocks. It was possible to divide chromosome 1B into 17 subregions. Nineteen genetic markers are physically mapped to nine subregions of chromosome 1B. Comparison of the cytological map of chromosome 1B with an RFLP-based genetic linkage map of Triticum tauschii revealed that the linear order of the genetic markers was maintained between chromosome 1B of hexaploid wheat and 1D of T. tauschii. Striking differences were observed between the physical and genetic maps in relation to the relative distances between the genetic markers. The genetic markers clustered in the middle of the genetic map were physically located in the distal regions of both arms of chromosome 1B. It is unclear whether the increased recombination in the distal regions of chromosome 1B is due to specific regions of increased recombination or a more broadly distributed increase in recombination in the distal regions of Triticeae chromosomes.Key words: common wheat, chromosome 1B, homozygous deletion lines, physical map, RFLP markers.

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