Methods and Means to Modify Fiber Strength in Fiber-Producing Plants

Abstract

This invention relates to the field of agriculture, more specifically to the use of molecular biology techniques to alter fiber-producing plants, particularly cotton plants, and/or accelerate breeding of such fiber-producing plants. Methods and means are provided to alter fiber qualities, such as increasing fiber strength. Methods are also provided to identify molecular markers associated with fiber strength in a population of cotton varieties and related progenitor plants.

1 . A non-naturally occurring  Gossypium hirsutum  plant, and parts and progeny thereof, characterized in that the functional expression of at least one allele of at least one fiber-specific GLUC gene that is functionally expressed during the fiber strength building phase, in particular the fiber maturation phase, of fiber development is abolished, wherein the GLUC gene is a GLUC1.1A gene encoding a GLUC protein that has at least 97% sequence identity to SEQ ID NO: 4. 
     
     
         2 . The plant of  claim 1 , wherein the amount of functional GLUC protein is significantly reduced in fibers during the fiber strength building phase, in particular the fiber maturation phase, of fiber development compared to the amount of functional GLUC protein produced in fibers during the fiber strength building phase, in particular the fiber maturation phase, of fiber development in a plant in which the functional expression of the at least one GLUC allele is not abolished. 
     
     
         3 . The plant of  claim 1 , wherein the strength of the fibers is significantly increased compared to the strength of the fibers in a plant in which the functional expression of the at least one GLUC allele is not abolished. 
     
     
         4 . The plant of  claim 3 , wherein the strength of the fibers is on average
 a. between about 5% and about 10%, preferably about 7.5%, higher;   b. between about 1.6 g/tex and about 3.3 g/tex, preferably about 2.5 g/tex, higher;   c. between about 34.6 g/tex and about 36.3 g/tex, preferably about 35.5 g/tex.   
     
     
         4 . The plant of  claim 3 , which is characterized in that the functional expression of at least two alleles of at least one fiber-specific GLUC gene is abolished. 
     
     
         5 . A fiber obtainable from the fiber-producing plant of  claim 1 . 
     
     
         6 . A nucleic acid molecule encoding a non-functional GLUC1.1 protein having an amino acid sequence wherein at least one amino acid residue similar to the active site residues or to the glycosylation site residues of the GLUC1.1 protein of SEQ ID NO: 4 is lacking or is substituted for a non-similar amino acid residue. 
     
     
         7 . The nucleic acid molecule of  claim 6 , wherein the active site residues of the GLUC1.1 protein of SEQ ID NO: 4 are selected from the group consisting of Tyr48, Glu249, Trp252, and Glu308, and wherein the glycosylation site residue of the GLUC1.1 protein of SEQ ID NO: 4 is Asn202. 
     
     
         8 . The nucleic acid molecule of  claim 6 , comprising:
 d. a nucleic acid sequence having at least 92% sequence identity to SEQ ID NO: 3 from nucleotide 101 to 1078, wherein at least one nucleic acid residue is deleted, inserted or substituted;   e. a nucleotide sequence at least 92% identical to the nucleic acid sequence of SEQ ID NO: 54 from nucleotide 50 to 589;   f. the nucleic acid sequence of SEQ ID NO: 54 from nucleotide 50 to 589;   g. a nucleic acid sequence having at least 92% sequence identity to SEQ ID NO: 1 from nucleotide 2410 to 3499, wherein at least one nucleic acid residue is deleted, inserted or substituted;   h. a nucleotide sequence at least 92% identical to the nucleic acid sequence of SEQ ID NO: 5 from nucleotide 63 to 711;   i. the nucleic acid sequence of SEQ ID NO: 5 from nucleotide 63 to 711.   
     
     
         9 . A method for generating and/or selecting a non-naturally occurring  Gossypium hirsutum  plant, and parts and progeny thereof, wherein the functional expression of at least one allele of at least one fiber-specific GLUC gene that is functionally expressed during the fiber strength building phase, in particular the fiber maturation phase, of fiber development is abolished, comprising the step of:
 mutagenizing at least one allele of the GLUC gene, or   introgressing at least one allele of a non-functionally expressed ortholog of the GLUC gene or at least one allele of a mutagenized GLUC gene, or   introducing a chimeric gene comprises the following operably linked DNA elements:   a. a plant expressible promoter,   b. a transcribed DNA region, which when transcribed yields an inhibitory RNA molecule capable of reducing the expression of the GLUC allele, and   c. a 3′ end region comprising transcription termination and polyadenylation signals functioning in cells of the plant,   
       wherein the GLUC gene is a GLUC1.1A gene encoding a GLUC1.1A protein that has at least 97% sequence identity to SEQ ID NO: 4. 
     
     
         10 . The method of  claim 9 , wherein the non-functionally expressed ortholog of the GLUC1.1A gene is derived from a  Gossypium barbadense,    
     
     
         11 . A method for altering the properties of a fiber in a  Gossypium hirsutum  plant, particularly increasing the strength of a fiber, comprising the steps of:
 generating and/or selecting a non-naturally occurring fiber-producing plant, and parts and progeny thereof, wherein the functional expression of at least one allele of at least one fiber-specific GLUC1.1A gene that is functionally expressed during the fiber strength building phase, in particular the fiber maturation phase, of fiber development is abolished, according to  claim 9 ,   selecting a plant with an altered fiber strength, in particular an increased fiber strength.