Submitted to: Plant Cell Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/27/2007
Publication Date: 12/13/2007
Citation: Zhang, J., Turley, R.B., Stewart, J.M. 2007. Comparative Analysis of Gene Expression Between CMS-D8 Restored Plants and Normal Non-restoring Fertile Plants in Cotton by Differential Display. Plant Cell Reports. 27:553-561
Interpretive Summary: One method to improve cotton yields and quality is to produce hybrid plants which have increased vigor. Producing hybrid plants on a large scale becomes a problem since cotton is predominantly a self pollinated crop with pollen (male) from a flower fertilizing the egg cell (female) of the same flower. Mass production of cotton hybrids has been accomplished in third world countries by manually removing male parts of the flower and fertilizing with flowers from a different type of cotton plant which is very labor intensive and costly. We are researching an alternative method for producing hybrids using the cytoplasmic male sterility (CMS) trait, which is characterized by cotton plants which either produce sterile pollen or no pollen. Production of hybrid CMS cotton would be greatly simplified and would require planting a single line of pollen producing plants in close proximity and using natural insect pollination. We have identified a number genes which may be valuable in understanding CMS and in producing more CMS cotton lines. Facilitating the production of hybrid cottonseed would allow producers to benefit from improved yields and cotton quality while moderating cost of cottonseed production.
Technical Abstract: CMS-D8 and its restorer were developed by introducing the cytoplasm and nuclear gene Rf2 from the wild diploid Gossypium trilobum (D8) into the cultivated tetraploid Upland cotton (G. hirsutum). No information is available on how the Rf2 gene interacts with CMS-associated genes and how CMS-D8 cytoplasm affects nuclear gene expression. The objective of this study was to identify differentially expressed genes in anther tissues between the non-restoring fertile maintainer ARK8518 (rf2rf2) and its isogenic heterozygous D8 restorer line, ARK8518R (Rf2rf2) with D8 cytoplasm, by mRNA differential display (DD). Out of more than 3,000 DDRT-PCR bands amplified by 31 primer combinations from 12 anchor primers and eight arbitrary decamer primers, approximately 100 bands were identified as being qualitatively differentially displayed. A total of 38 cDNA fragments including 12 preferentially expressed cDNA bands in anther were isolated, cloned and sequenced. Reverse Northern blot analysis showed that only 4 genes, including genes encoding a Cys-3-His zinc finger protein and aminopeptidase, were up-regulated, while 22 genes, including genes for phosphoribosylanthranilate transferase (PAT), starch synthase (SS), 4-coumarate-CoA ligase, electron transporter, calnexin, arginine decarboxylase, and polyubiquitin, were down-regulated in the heterozygous restorer 8518R. The down-regulation of SS explains the lack of starch accumulation in sterile rf2 pollen grains in the heterozygous restored plants. The molecular mechanism of CMS and its restoration, specifically the possible roles of SS and PAT genes in relation to restoration of Rf2 to CMS-D8, are discussed. This investigation represents the first account of such an analysis in cotton.