Agriculture : Crop production


Soybeans with Increased Resistance to Sclerotinia Stem Rot and Drought Tolerance

UW–Madison researchers have demonstrated that knocking down expression of a specific soybean respiratory burst oxidase homolog protein (GmRBOH-VI) leads to enhanced resistance to S. sclerotiorum and confers drought tolerance.

Using protein sequence similarity searches, the researchers identified seventeen GmRBOHs and studied their contribution to Sclerotinia disease development, drought tolerance and nodulation. Transcript analysis of all seventeen GmRBOHs revealed that out of the six identified groups, group VI (GmRBOH-VI) was specifically and drastically induced following S. sclerotiorum challenge. Virus-induced gene silencing of GMRBOH-VI resulted in enhanced resistance to the fungus and, coincidently, drought stress.

Based on these discoveries, the researchers have developed modified soybeans and production methods available for licensing.

Shade-Resistant, Higher-Yield Crops with Modified Phytochromes

UW–Madison researchers have enhanced the light sensitivity of plants by modifying their Phytochrome B (PhyB) gene. Using standard techniques, the researchers made several mutations to the gene sequence. One important change was the substitution of a different amino acid for Tyrosine 361. The modified seedlings grew smaller, exhibiting decreased height, stem diameter, petiole and internode length.

Singlet Oxygen-Resistant Technologies

UW-Madison researchers have developed a method of altering the response of cells to 1O2 by modulating the interaction between an anti-sigma factor, ChrR, and σE, or by altering the expression of a gene product required for viability in the presence of 1O2. The growth of phototrophic bacteria exposed to 1O2 may be inhibited by administering an anti-sigma agent, such as ChrR, to reduce the availability of σE On the other hand, a bacterium or other organism may be protected from damage from 1O2 by modifying the genes in the σE regulon or by modifying ChrR to alter binding between it and σE.

Vernalization-Related Molecules and Methods for Inducing Permanent Changes in Plant Gene Expression

UW-Madison researchers have identified a novel polypeptide, VIN3, that plays a role in vernalization. During exposure to cold, VIN3 represses FLC, one of the two main genes responsible for flowering in plants. High FLC expression levels inhibit flowering; thus, by repressing FLC, VIN3 helps promote flowering. During vernalization, VIN3 likely represses FLC by hypoacetylating FLC chromatin, triggering histone modifications that result in a stable, repressed heterochromatin state.

This VIN3-mediated process can be applied in other organisms to cause a permanent change in gene expression. The components of the process, including VIN3, can be used to transform a host organism in which a selected gene has been modified to contain certain FLC sequences. These components are preferably under the control of an inducible promoter, which allows the user to trigger at will the development of stable repressed or active chromatin at the target gene. This, in turn, results in an alteration in gene expression that is stable through subsequent plant cell mitotic cycles.