Methods for producing hybrid seed

Abstract

This invention provides methods for producing a non-natural hybrid seed. Also disclosed are specific miRNAs and miRNA recognition sites useful for conferring inducible sterility on a crop plant, and recombinant DNA construct including such exogenous miRNA recognition sites.

Description

PRIORITY CLAIMS AND REFERENCE TO RELATED APPLICATIONS [0001] This application claims benefit of priority to U.S. Provisional Patent Applications No. 60 / 726,106, filed on 13 Oct. 2005, and 60 / 836,246, filed on 7 Aug. 2006, which are incorporated by reference in their entirety herein.INCORPORATION OF SEQUENCE LISTINGS [0002] The sequence listing that is contained in the file named “38-21(54232)C.rpt” which is 70 kilobytes (measured in operating system MS-Windows), was created on 19 Sep. 2006, and is located in computer readable form on a compact disk (CD-R), is filed herewith and incorporated herein by reference. The sequence listings contained in the files “38-21(54232)A.rpt” (file size of 61 kilobytes, recorded on 12 Oct. 2005, and filed with U.S. Provisional Application 60 / 726,106 on 13 Oct. 2005) and “38-21(54232)B.rpt” (file size of 68 kilobytes, recorded on 7 Aug. 2006, and filed with U.S. Provisional Application 60 / 836,246 on 7 Aug. 2006) are incorporated by reference in their ...

AI Technical Summary

Benefits of technology

[0018] In another aspect, this invention provides a method for producing a hybrid seed, including the steps of: (a) providing a first parent plant including a transgenic plant grown from a first transgenic plant cell containing in its genome a first recombinant DNA construct that transcribes to RNA including (i) at least one exogenous miRNA recognition site recognizable by a first mature miRNA, and (ii) a first messenger RNA encoding a protein imparting tolerance to a first herbicide, wherein the first mature miRNA is specifically expressed in male reproductive tissue of the first parent plant, thereby specifically suppressing expression of the protein in the male reproductive tissue, and wherein male sterility of the first parent plant is inducible by application of the first herbicide to the first parent plant; (b) providing a second parent plant including a transgenic plant grown from a second transgenic plant cell containing in its genome

Problems solved by technology

A major limitation in the production of hybrid seed for many crop species is the lack of simple, reliable and economical methods of generating sterility in at least one parent (especially the male parent, to result in male-sterility while leaving female gametes intact and accessible for pollination by a suitable pollen donor).

In some species, this is a straightforward although labor-intensive and therefore expensive process (e.g., detasselling in maize).

In other species, such physical emasculation is difficult because of the plant's anatomy.

However, the levels of glyphosate necessary to kill most of the male gametes while leaving a sufficient number of female gametes still capable of fertilization often resulted in stunting or chlorosis of the plants.

Thus, a major drawback of using glyphosate as a gametocide, as is generally true with most chemical gametocides, is the phytotoxic side effects resulting from lack of sufficient selectivity for gametes.

Commercial production of hybrid seed using chemical gametocides is limited primarily by their lack of selectivity for gametes in general.

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