Main conclusion <p>We generated triploid hybrids of <i>I. trifida</i> and <i>I. tabascana</i>, providing insights into sweetpotato evolution and bridge germplasm for genetic improvement.</p> Abstract <p>Sweetpotato [<i>Ipomoea batatas</i> (L.) Lam.] (2n = 6<i>x</i> = 90) is an important root crop whose genomic polyploidisation process remains incompletely understood and highly complex. Its wild relatives are favoured for the study of genome formation, polyploidy processes and genetic improvement in sweetpotato. In this study, we obtained two triploid hybrids via reciprocal crosses between the closest diploid (<i>I</i>. <i>trifida</i>, 2n = 2<i>x</i> = 30) and the closer tetraploid (<i>I</i>. <i>tabascana</i>, 2n = 4<i>x</i> = 60) wild relatives of sweetpotato. To verify the authenticity of these two hybrids, molecular marker analysis, flow cytometry analysis, chromosome counting, morphological characterisation, pollen viability testing and meiotic observation were performed. Through InDel marker analysis, nine primer pairs consistently amplified parent-specific bands in the hybrids. Ploidy characterisation showed that both hybrids were triploid with 45 chromosomes. Morphologically, the two hybrids inherited many traits from both parents whilst producing some variation, such as both round and pentagonal corollas and purple stigmas with two or three lobes. Some pollen grains from the hybrids were fertile. The hybrids showed many abnormalities during meiosis, such as lagging chromosomes and uneven chromosome distribution. The triploid hybrids produced in this study can be used to infer early triploid genomic events during the origin and evolution of sweetpotato and to develop bridge germplasm for its genetic improvement.</p>

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Characterisation and meiotic observation of triploid hybrids of Ipomoea trifida (2x) and Ipomoea tabascana (4x) by reciprocal crosses

  • Zongkuan Weng,
  • Lukuan Zhao,
  • Jiangong Li,
  • Yao Wang,
  • Yitong Deng,
  • Lingxiao Zhao,
  • Shizhuo Xiao,
  • Tianni Yang,
  • Xibin Dai,
  • Zhilin Zhou,
  • Qinghe Cao

摘要

Main conclusion

We generated triploid hybrids of I. trifida and I. tabascana, providing insights into sweetpotato evolution and bridge germplasm for genetic improvement.

Abstract

Sweetpotato [Ipomoea batatas (L.) Lam.] (2n = 6x = 90) is an important root crop whose genomic polyploidisation process remains incompletely understood and highly complex. Its wild relatives are favoured for the study of genome formation, polyploidy processes and genetic improvement in sweetpotato. In this study, we obtained two triploid hybrids via reciprocal crosses between the closest diploid (I. trifida, 2n = 2x = 30) and the closer tetraploid (I. tabascana, 2n = 4x = 60) wild relatives of sweetpotato. To verify the authenticity of these two hybrids, molecular marker analysis, flow cytometry analysis, chromosome counting, morphological characterisation, pollen viability testing and meiotic observation were performed. Through InDel marker analysis, nine primer pairs consistently amplified parent-specific bands in the hybrids. Ploidy characterisation showed that both hybrids were triploid with 45 chromosomes. Morphologically, the two hybrids inherited many traits from both parents whilst producing some variation, such as both round and pentagonal corollas and purple stigmas with two or three lobes. Some pollen grains from the hybrids were fertile. The hybrids showed many abnormalities during meiosis, such as lagging chromosomes and uneven chromosome distribution. The triploid hybrids produced in this study can be used to infer early triploid genomic events during the origin and evolution of sweetpotato and to develop bridge germplasm for its genetic improvement.