Stable transformation and expression of GhEXPA8 fiber expansin gene to improve fiber length and micronaire value in cotton

Abstract

Cotton fiber is multigenic trait controlled by number of genes. Previous studies suggest that one of these genes may be responsible for switching cotton fiber growth on and off to influence the fiber quality produced from a cotton seed. In the present study, the Gossypium hirsutum GhEXPA8 fiber expansin gene was introduced into local cotton variety NIAB 846 by using an Agrobacterium-mediated gene transformation. The neomycin phosphotransferase (NPTII) gene was used as a selection marker for screening of putative transgenic cotton plants. Integration and expression of the fiber expansin gene in cotton plants was confirmed with molecular techniques including Southern blot analyses, real-time PCR. Cellulose assay was used for measurement of cellulose contents of transgenic cotton fiber. The data collected from 3 years of field performance of the transgenic cotton plants expressing GhEXPA8 showed that significant improvement has been made in fiber lengths and micronaire values as compared to control G. hirsutum variety NIAB 846 cotton plants. Statistical techniques were also used for analysis of fiber and agronomic characteristics. The results of this study support improvement of cotton fiber through genetic modification.

Genome-wide identification of expansin gene family reveals expansin genes are involved in fibre cells growth in cotton

“…The function of expansins has been reported in cotton fibre elongation [9,10,17]. GhEXPA4f, was highly consistent with the report of Harmer et al where GhExp1 transcripts were highly abundant in the fibre [15], and its homologous gene GhEXPA2 showed a similar expression pattern.…”

“…Many expansin gene families have been identified from eudicots and monocotyledons, including Arabidopsis, grape, jujube, Chinese cabbage, maize, and rice, [4,[27][28][29][30]. However, expansins have rarely been analysed in cotton, except for a few studies on the expression levels of GhEXP genes, transcriptional regulation, and genetic transformation studies [10,[15][16][17]. In recent years, the completion of the cotton genomic sequence through multiple sequencing technologies has provided powerful data support for analysing gene families [22,24,31,32], which will greatly facilitate the identification and analysis of cotton gene families at the whole genome scale.…”

“…At present, studies of expansins have shown that they can participate in many developmental processes, and are thought to function in cell growth and enlargement, pollen tube invasion of the stigma (in grasses), wall disassembly during fruit ripening, abscission, stress resistance, and other cell separation events [1,3,7,8]. Cotton is the most important natural fibre crop worldwide and expansins play an important role in fibre cells [9,10]. The mRNA levels of expansins were firstly reported to be high during cell elongation but decreased when cell elongation ceased [11].…”

“…The mRNA levels of expansins were firstly reported to be high during cell elongation but decreased when cell elongation ceased [11]. Field experiment data showed that expansins improved cotton fibre length and micronaire value [10].…”

“…Subsequently, some expansin genes preferentially expressed in cotton fibres were isolated and identified using several different approaches, including cDNA arrays, subtractive PCR, RT-PCR, and SNP-based chromosomal assignment [12,13], and researchers have a preliminary understanding of the function of these cotton expansin genes at the transcript level [12,14,15]. The functions of expansin genes have been further investigated in cotton fibre development [9,10,16,17]. For example, GhRDL1 is localized in the cell wall and interacts with GhEXPA1.…”