State Key Laboratory of Cotton Biology, Institute of Cotton Research, the Chinese Academy of Agricultural Sciences, Anyang, 455000, China.
J Integr Plant Biol. 2013 Jul;55(7):643-53. doi: 10.1111/jipb.12068.
Sucrose synthase (Sus) is a key enzyme in plant sucrose metabolism. In cotton, Sus (EC 2.4.1.13) is the main enzyme that degrades sucrose imported into cotton fibers from the phloem of the seed coat. This study demonstrated that the genomes of Gossypium arboreum L., G. raimondii Ulbr., and G. hirsutum L., contained 8, 8, and 15 Sus genes, respectively. Their structural organizations, phylogenetic relationships, and expression profiles were characterized. Comparisons of genomic and coding sequences identified multiple introns, the number and positions of which were highly conserved between diploid and allotetraploid cotton species. Most of the phylogenetic clades contained sequences from all three species, suggesting that the Sus genes of tetraploid G. hirsutum derived from those of its diploid ancestors. One Sus group (Sus I) underwent expansion during cotton evolution. Expression analyses indicated that most Sus genes were differentially expressed in various tissues and had development-dependent expression profiles in cotton fiber cells. Members of the same orthologous group had very similar expression patterns in all three species. These results provide new insights into the evolution of the cotton Sus gene family, and insight into its members' physiological functions during fiber growth and development.
蔗糖合酶（Sus）是植物蔗糖代谢中的关键酶。在棉花中，Sus（EC 2.4.1.13）是将种子壳韧皮部中导入棉花纤维的蔗糖降解的主要酶。本研究表明，陆地棉（Gossypium arboreum L.）、雷蒙德氏棉（G. raimondii Ulbr.）和海岛棉（G. hirsutum L.）的基因组分别包含 8、8 和 15 个 Sus 基因。对它们的结构组织、系统发育关系和表达谱进行了分析。基因组和编码序列的比较鉴定出多个内含子，这些内含子在二倍体和异源四倍体棉花物种之间的数量和位置高度保守。大多数系统发育枝系都包含来自这三个物种的序列，表明四倍体 G. hirsutum 的 Sus 基因来源于其二倍体祖先。一个 Sus 组（Sus I）在棉花进化过程中发生了扩张。表达分析表明，大多数 Sus 基因在不同组织中差异表达，并在棉花纤维细胞中有发育依赖性的表达谱。同一直系同源基因家族的成员在所有三个物种中的表达模式非常相似。这些结果为棉花 Sus 基因家族的进化提供了新的见解，并深入了解了其成员在纤维生长和发育过程中的生理功能。
