Organization and evolution of transposable elements along the 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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Wheat × maize hybridization

Canadian Journal of Genetics and Cytology ◽

10.1139/g86-046 ◽

1986 ◽

Vol 28 (2) ◽

pp. 313-316 ◽

Cited By ~ 129

Author(s):

D. A. Laurie ◽

M. D. Bennett

Keyword(s):

Triticum Aestivum ◽

Zea Mays ◽

Transposable Elements ◽

Bread Wheat ◽

Chromosome Elimination ◽

Wide Crosses ◽

Maize Chromosome ◽

Haploid Production ◽

Cytogenetic Evidence ◽

The Cross

Cytogenetic evidence is presented that the cross between hexaploid bread wheat (Triticum aestivum, 2n = 42) and maize (Zea mays, 2n = 20) results in a hybrid zygote with one complete haploid chromosome set from each parent. Maize chromosomes are subsequently eliminated. This sytem has potential for wheat haploid production and may also allow segments of maize DNA, including transposable elements, to be transferred to wheat.Key words: wide crosses, wheat, maize, chromosome elimination, haploids.

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