Regulation of Mu element copy number in maize lines with an active or inactive Mutator transposable element system

Abstract

In the progeny of an active Mutator plant, the number of Mu elements increases on self-pollination and maintains the average parental Mu content on outcrossing to a non-Mutator line; both patterns of transmission require an increase in the absolute number of Mu elements from one generation to the next. The same average copy number of Mu elements is transmitted through the male and female, but there is wide variation in the absolute copy number among the progeny. In inactive Mutator plants-defined both by the loss of somatic instability at a reporter gene (bronze2-mu1) and by modification of the HinfI sites in the terminal inverted repeat sequences of Mu elements - the absolute copy number of Mu elements is fixed in the parent. Thus, in outcrosses Mu element number is halved, and on self-pollination Mu copy number is constant. Reactivation of somatic mutability at cryptic bz2-mu1 alleles in inactive individuals by crossing to an active line seems not to involve an increase in Mu element copy number transmitted by the inactive individual. These and other results suggest that increases in Mu copy number occur late in plant development or in the gametophyte rather than after fertilization.

Maintaining and restoring cytoplasmic male sterility systems in pepper (Capsicum annuum L.)

“…Total DNA was extracted from the fresh leaves of each plant (Walbot and Warren, 1988). The primers were designed according to the method of Gulyas et al (2006).…”

Analysis of Fertility Restoration by Using Cytoplasmic Male-sterile Red Pepper (Capsicum annuum L.) Lines

“…Genomic DNA was isolated from young leaf tissue by the crude nuclear pellet method (Walbot and Warren 1988). Primers specific to the restorer gene (Yanagawa et al 1996, Gene Bank Accessions: E15678 and E15679) were used for PCR amplification with the following nucleotide sequences: CRF3-S 5′-ATTTTCAGATTGTGGCGACG-3′ and CRF1-S 5′-CGACCATCACGACGAGG-3′.…”

Mutator and MULE Transposons

“…Lines carrying large numbers of these elements can exhibit mutation frequencies 50 to 100 times that of background (1,2). This is due to a very high transposition frequency, which can exceed one new insertion per element per generation (3,4), as well as a propensity to insert into or near genes (5). Because they are so mutagenic, Mutator elements have been very useful in both forward and reverse genetic screens in maize and recent high-throughput methodologies have only made the system more so (6).…”