Chromosome elimination by super-wide hybridization between wheat or oat and pearl millet:CENH3 dynamics in the hybrid embryo cells

摘要

Sustainable production of food is threatened by global climate change,expansion of the world population and water resource shortage.Plant breeding for the sustainable food production is performed all over the world.In wheat breeding,germplasm enhancement and development of genes to combat climate change and water shortage is required.Pearl millet(family Poaceae,sub-family Panicoideae)is a drought and salinity tolerant crop,and thus,it is important in the Africa and Indian semi-arid regions.Wheat and oat(family Poaceae,sub-family Pooideae)are important crops for human and animals.However,they do not have a strong tolerance to drought and salinity.We intended to introduce the millet tolerant genes to wheat and oat plants by super-wide cross method.First we crossed wheat and oat with pearl millet and observed the dynamics of millet chromosomes in the hybrid embryo cells seven days after pollination using the fluorescence in situ hybridization(FISH)method and immunostaining method with CENH3(centromere histone H3)antibody.In the cross between oat and pearl millet,all pearl millet chromosomes were retained,and CENH3 were located in the oat and pearl millet centromere.As a result,we could obtain true oat-pearl millet hybrids,but the hybrids showed sever necrosis.On the other hand,in the cross between wheat and pearl millet,the pearl millet chromosomes were gradually eliminated during embryogenesis.The eliminated chromosomes showed sever chromosome aberrations,such as breakage,chromosome bridge,non-disjunction and micronuclei formation.However,CENH3 were localized both on wheat and pearl millet centromere.These results indicated that the cause of the chromosome elimination in wheatpearl millet hybrids was not simply explained as a malfunction of the kinetochore binding to the spindles.The wheat and oat plants with a pearl millet chromosome may be used as breeding materials in wheat improvement for harsh environmental condition.