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Title: REGULATION OF THE MAIZE UBIQUITIN (UBI-1) PROMOTER IN DEVELOPING MAIZE (ZEA MAYS L.) SEEDS EXAMINED USING TRANSIENT GENE EXPRESSION IN KERNELS GROWN IN VITRO

Author
item Muhitch, Michael
item Shatters, Robert - Bob

Submitted to: Plant Cell Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/21/1997
Publication Date: N/A
Citation: N/A

Interpretive Summary: Corn seeds are susceptible to fungi that produce toxins which may compromise food or feed safety. We desire to add fungal resistance genes to corn to prevent seed fungal invasion. Testing new genes in corn seeds, however, is hampered by the need to wait until the plants have set seed to check the new trait. To get around this, we have adapted a system wherein developing seeds are taken from the plant and placed in a growth medium to use as a quick way to check newly introduced genes. To test the system, we demonstrated that when a natural gene was introduced into the seed, it behaved as expected. We will now use this system in future research to test the ability of introduced genes to prevent or delay fungal entry and subsequent toxin production in corn seeds.

Technical Abstract: Individual maize (Zea mays L.) kernels cultured on defined medium were used as an experimental system for testing the effects of stress and hormone treatment on the transient expression of maize ubiquitin (Ubi1) promoter-driven beta-glucuronidase (GUS) activity introduced by particle bombardment. Histochemical detection of beta-GUS activity in untreated kernels showed Ubi1/GUS transient expression to be confined to meristematic and newly differentiated cells, consequently, staining decreased dramatically with kernel maturation. Transient expression of Ubi/GUS in kernels was not affected by wounding, ethylene treatment, pathogen invasion, or heat shock, except under certain conditions where heat shock appeared to decrease histochemical staining moderately. In contrast, indole acetic acid and kinetin both stimulated transient expression, indole acetic acid stimulation being particularly intense in the endosperm subaleurone where storage protein synthesis occurs. These experiments demonstrate the utility of the in vitro kernel culture system for studying the effects of medium components, pathogen invasion or stress on transient gene expression in developing maize seeds.