Genome-wide investigation and expression profiling of APX gene family in Gossypium hirsutum provide new insights in redox homeostasis maintenance during different fiber development stages

Chengcheng Tao,Quanliang Xie,Hongbin Li,Xiang Jin,Xuchu Wang,Liping Zhu

doi:10.1007/s00438-017-1413-2

Chengcheng Tao, Quanliang Xie + Show 4 more

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https://doi.org/10.1007/s00438-017-1413-2

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Abstract

Ascorbate peroxidase (APX) is a member of heme-containing peroxidases which catalyze the H2O2-dependent oxidation of a wide range of substrates in plants and animals. As is known, H2O2 acts as a signaling molecule in the regulation of fiber development. Our previous work reported that ascorbate peroxidase 1 (GhAPX1) was important for cotton fiber elongation. However, knowledge about APX gene family members and their evolutionary and functional characteristics in cotton is limited. Here, we report 26 GhAPX genes by genome-wide investigation of tetraploid cotton Gossypium hirsutum. Phylogenetic and gene structure analyses classified these APX members into five clades and syntenic analysis suggested two duplication events. Expression profiling of the 26 APXs revealed that ten members are expressed in cotton fibers. Notably, GhAPX10A, GhAPX10D, GhAPX12A, and GhAPX12D showed high expression levels in 30-day fiber, while GhAPX1A/D, GhAPX3A/D, and GhAPX6A/D showed very low expression levels. The enzyme activity and H2O2 content assays revealed that cotton fiber kept high enzyme activity and the lowest H2O2 level in 30-day fibers, indicating that other than GhAPX1, the newly reported APX members are responsible for the reactive oxygen species homeostasis in the cotton fiber maturation stages. Expression profiling of ten fiber-expressed APXs after phytohormone treatments revealed their regulation patterns by different stimuli, suggesting that GhAPX1, GhAPX12A, and GhAPX12D are responsible to most phytohormone treatments. Our data provided evolutionary and functional information of GhAPX gene family members and revealed that different members are responsible to redox homeostasis during different cotton fiber development stages.

Highlights

Tetraploid upland cotton (Gossypium hirsutum) is the most widely cultivated cotton plants, which is the most important resource of natural fiber for textile industry (Zhu 2016)
Several reports indicated that GhAPX1 plays important roles during cotton fiber initiation and elongation stages (Fig. S1) (Shi et al 2006; Li et al 2007; Yang et al 2008; Zheng et al 2014; Guo et al 2016)
All the fiber-expressed GhAPX members except for GhAPX3A/D illustrated significant induced expression after H2O2 treatment (Fig. 7f). These results suggested that GhAPX genes may perform multiple functions in the process of H2O2 and phytohormone regulated cotton fiber development

Summary

Introduction

Tetraploid upland cotton (Gossypium hirsutum) is the most widely cultivated cotton plants, which is the most important resource of natural fiber for textile industry (Zhu 2016). Benefit from the publication of the genome of upland cotton (70,478 predicted protein coding genes), a large number of functional genes and their gene family members involved in cotton fiber development have been reported (Huang et al 2015; Guo et al 2016; Zhang et al 2016; Wu et al 2017). Reactive oxygen species (ROS) can be continuously produced in all aerobic organisms to take important role as regulator for cellular response to environmental factors in plants (Alscher et al 1997; Pandey et al 2017). Despite the vital role in cell development, ROS accumulation could cause severe damages, plants developed a complex antioxidant system to prevent cellular damage generated by ROS, such as ascorbic acid (AsA), glutathione (GSH), and carotenoids (Smirnoff 2000)

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