Plants with useful traits and related methods
The present invention provides methods for obtaining plants that exhibit useful traits by transient suppression of the MSH1 gene of the plants. Methods for identifying genetic loci that provide for useful traits in plants and plants produced with those loci are also provided. In addition, plants that exhibit the useful traits, parts of the plants including seeds, and products of the plants are provided as well as methods of using the plants.
1. A method for producing a plant exhibiting a useful trait comprising the steps of:
a. suppressing expression of an endogenous MSH1 gene(s) in a first parental plant by introducing into the first parental plant:
(i) a transgene comprising an MSH1 gene or MSH1 gene fragment of at least 18 to about 500 or more nucleotides that suppresses expression of the endogenous MSH1 gene(s) by providing a small inhibitory RNA (siRNA), a microRNA (miRNA), a co-suppressing sense RNA, or an anti-sense RNA directed against the endogenous MSH1 gene;
(ii) a mutation in the MSH1 gene(s) of the first parental plant; or,
(iii) a nucleic acid comprising an MSH1 gene fragment of 18 to about 500 or more nucleotides that is directed against the endogenous MSH1 gene;
b. selfing or crossing the parental plant of step (a), progeny of said parental plant of step (a), a plant obtained from said plant cell of step (a), or progeny of a plant obtained from said plant cell of step (a), wherein the cross is to a second plant wherein MSH1 had not been suppressed;
c. screening a population of progeny plants obtained from said self or cross of step (b) for at least one useful trait selected from the group consisting of improved yield under non-stress conditions, improved yield under abiotic stress conditions, or improved resistance to a fungal pathogen, wherein a portion of said population of progeny plants express MSH1;
d. selecting a progeny plant having improved yield under non-stress conditions, improved yield under abiotic stress conditions, or improved resistance to a fungal pathogen in comparison to a control plant, and
e. cultivating the selected progeny plant of step (d);
wherein the screening step (c) or the selecting step (d) comprises measuring the methylation status of chromosomal DNA of one or more altered chromosomal loci in the nucleus of plant cells of a progeny plant of step (c) or step (d), respectively, and the methylation status of chromosomal DNA in the nucleus of plant cells of a control plant that does not exhibit the useful trait, wherein said improved yield or resistance exhibits nuclear inheritance and correlates with one or more epigenetic changes in nuclear chromosomal loci of the progeny plant, and is not caused by substoichiometric shifting (SSS) in mitochondria of the selected progeny plant and wherein said selected progeny plant expresses MSH1, thereby producing a plant exhibiting the useful trait.
2. The method of claim 1 , wherein suppression of MSH1 expression is effected with a transgene or a nucleic acid comprising a polynucleotide of 21 or more nucleotides in length.
3. The method of claim 1 , wherein said method further comprises the step of producing seed from: i) a selfed progeny plant of step (d), ii) an out-crossed progeny plant of step (d), or, iii) from both of a selfed and an out-crossed progeny plant of step (d).
4. The method of claim 3 , wherein said method further comprises the step of assaying said seed or plants grown from said seed for the presence of said trait.
5. The method of claim 1 , wherein said transgene suppresses expression of MSH1 by providing a small inhibitory RNA (siRNA).
6. The method of claim 1 , wherein said first parental plant or plant cell is obtained by crossing an female plant with a distinct male plant, wherein at least one of said female or male plants comprise the transgene that suppresses expression of the endogenous MSH1 gene of said parental plant(s).
7. The method of claim 1 , wherein said first parental plant or plant cell was isogenic to said second plant prior to suppression of MSH1 in said first parental plant or plant cell.
8. The method of claim 1 , wherein said trait is improved yield under non-stress conditions or improved yield under abiotic stress conditions.
9. The method of claim 1 , wherein suppression of MSH1 expression is effected with a MSH1 nucleic acid fragment of 19 nucleotides to about 500 nucleotides.
10. The method of claim 1 , wherein said progeny plant in step (d) or progeny thereof exhibit an improvement in said trait in comparison to a plant that had not been subjected to suppression of MSH1 expression but was otherwise isogenic to said first parental plant or plant cell.
11. The method of claim 1 , wherein said plant is a crop plant.
12. The method of claim 11 , wherein said crop plant is selected from the group consisting of corn, soybean, cotton, canola, wheat, rice, tomato, tobacco, millet, and sorghum.
13. The method of claim 12 , wherein said crop is sorghum.
14. The method of claim 13 , wherein said yield trait is selected from the group consisting of increased panicle length, panicle weight, dry biomass, and combinations thereof in comparison to a control plant.
15. The method of claim 1 , wherein said MSH1 gene or MSH1 gene fragment in said transgene or nucleic acid in step (a) comprises a polynucleotide with at least 90% nucleotide sequence identity to SEQ ID NO:3, SEQ ID NO:4, SEQ ID NO:5, SEQ ID NO:6, SEQ ID NO:7, or SEQ ID NO:14 and wherein the MSH1 gene fragment is 19 nucleotides to about 500 or more nucleotides in length.
16. The method of claim 15 , wherein the plant is a soy, corn, tomato, sorghum, rice, or cotton plant and wherein said MSH1 gene or MSH1 gene fragment comprises a polynucleotide with at least 90% nucleotide sequence identity to the corresponding nucleotide sequence of SEQ ID NO:3, SEQ ID NO:4, SEQ ID NO:5, SEQ ID NO:6, SEQ ID NO:7, or SEQ ID NO:14, respectively.