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Allopolyploidization in Cucumis contributes to delayed leaf maturation with repression of redundant homoeologous genes
Author(s) -
Yu Xiaqing,
Wang Xixi,
Hyldgaard Benita,
Zhu Zaobing,
Zhou Rong,
Kjær Katrine Heinsvig,
Ouzounis Theoharis,
Lou Qunfeng,
Li Ji,
Cai Qingsheng,
Rosenqvist Eva,
Ottosen CarlOtto,
Chen Jinfeng
Publication year - 2018
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/tpj.13865
Subject(s) - biology , cucumis , gene , genetics , chloroplast , chlorophyll , homologous chromosome , phenotype , botany
Summary The important role of polyploidy in plant evolution is widely recognized. However, many questions remain to be explored to address how polyploidy affects the phenotype of the plant. To shed light on the phenotypic and molecular impacts of allopolyploidy, we investigated the leaf development of a synthesized allotetraploid ( Cucumis × hytivus ), with an emphasis on chlorophyll development. Delayed leaf maturation was identified in C . × hytivus , based on delayed leaf expansion, initial chlorophyll deficiency in the leaves and disordered sink‐source transition. Anatomical observations also revealed disturbed chloroplast development in C . × hytivus . The determination of chlorophyll biosynthesis intermediates suggested that the chlorophyll biosynthesis pathway of C . × hytivus is blocked at the site at which uroporphyrinogen III is catalysed to coproporphyrinogen III . Three chlorophyll biosynthesis‐related genes, HEMA 1 , HEME 2 and POR , were significantly repressed in C . × hytivus . Sequence alignment showed both synonymous and non‐synonymous substitutions in the HEMA 1 , HEME 2 and POR genes of the parents. Cloning of the chlorophyll biosynthetic genes suggested the retention of homoeologs. In addition, a chimeric clone of the HEMA 1 gene that consisted of homologous genes from the parents was identified in C . × hytivus . Overall, our results showed that allopolyploidization in Cucumis has resulted in disturbed chloroplast development and reduced chlorophyll biosynthesis caused by the repressed expression of duplicated homologous genes, which further led to delayed leaf maturation in the allotetraploid, C . × hytivus . The preferential retention/loss of certain types of genes and non‐reciprocal homoeologous recombination were also supported in the present study, which provides new insights into the impact of allopolyploidy.