Genome-wide Analysis Of APX And 14-3-3gene Families In Four Gossypium Species

Cotton is an important economic crop in China,whose fiber is an important resource of textile industry.The main cotton cultivars include diploid Gossypium arboreum,tetraploid Gossypium hirsutum and Gossypium barbadense.Although diploid Gossypium raimondii does not produce cotton fiber,it is still of great significance as the ancestor of tetraploid Gossypium species.In this paper,a genome-wide analysis of the 14-3-3 gene family and APX gene family related to fiber development in the four Gossypium species mentioned above was performed,and the genes related to fiber development were screened through RNA-seq analysis and q PCR experiments.The main research results are as follows:A total of 91 14-3-3 genes and 72 APX genes were identified from the four Gossypium species.There is no significant difference in gene domain length and protein physicochemical properties among four cotton.According to the evolutionary tree,14-3-3 genes were divided into epsilon group and non-epsilon group;APX genes were divided into group I-V;each group contains four cotton genes;and genes closely related to evolution have similar gene structures.The genes of the two families were subdivided into 18 and 12 subgroups,respectively.The number of each tetraploid cotton genes in most subgroups is the sum of the number of two diploid cotton genes,and the few are less than that of the two diploid cotton genes.Most of the sister-clade genes come from two different cotton.The genes of the two families are unevenly distributed on the chromosomes,and each family has collinearity within and between the Gossypium species genomes,but there is no tandem duplication.The APX genes have similar position and equal number in At and Dt subgenomes of Gossypium barbadense.Most of the genes in the two families were selected by purification and a few were selected by positive selection.The two diploid cotton genes were isolated earliest.The 14-3-3 genes of Gossypium arboreum were separated from the two tetraploids earlier than the Gossypium raimondii,but the difference is not significant;while the APX genes of Gossypium hirsutum were separated from the two diploids earlier than the Gossypium barbadense.In conclusion,the two gene families were amplified mainly by segmental duplication,and they are very conservative in Gossypium species evolution.The genes amplification of tetraploid cotton mainly came from the polyploid process of heterohybridization between the two donor ancestors,but there were genes loss during the process.The APX gene family is particularly conserved in the evolution of Gossypium barbadense.RNA-seq analysis showes that the two families are abundantly expression in cotton tissues,and the sister clade genes have similar expression trend.79.17% and 45.45% of the colinear genes in the two families of Gossypium hirsutum are relatively high expression in fiber.The 14-3-3 genes selected forward are mostly tetraploid cotton genes and they have relatively high expression in fiber;while the APX genes selected forward do not have high expression in fiber.It is speculated that genes with close evolutionary relationship have similar gene functions;the genes of the two families in Gossypium hirsutum promote fiber production through segmental duplication;the 14-3-3 genes with positive selection play an important role in fiber development;and the APX genes with positive selection have functional differentiation.Finally,eight 14-3-3 genes and six APX genes related to Gossypium hirsutum fiber development are screened by q PCR experiments.The results of this study will be of great significance to elucidate and study the evolutionary mechanism and function of 14-3-3 and APX genes in Gossypium.It will provide a basis for the study of the evolution in Gossypium,and promote cotton molecular breeding.