10-Maydica Tani - Maydica 50 (2005): 19-23 DNA METHYLATION...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
ABSTRACT - Hybrid vigor or heterosis refers to the supe- riority in one or more characters of crossbred organisms relative to their inbred parents. This superiority can be re- lated to increase in size or growth rate and increase in yield. While the biological basis of heterosis remains un- known, accumulated data clearly suggest the significance of quantitative regulation of gene expression in heterotic phenomena. DNA methylation is an epigenetic, genome- wide general regulatory mechanism that affects the ex- pression of many genes important for the manifestation of heterosis. According to previous studies DNA methylation in maize varies among different genotypes (parental in- bred lines and hybrids) and developmental stages. Our recent studies indicate that growth conditions affect the level and pattern of DNA methylation. Parental inbred lines and hybrids were grown under two different plant densities: 1.5m (spread) and 0.25m (dense) distance be- tween individual plants with a density of 0.513 plants/m 2 and 18.5 plants/m 2 , respectively. The effect of density-in- duced stress on the pattern of methylation in certain sites of DNA was examined using the Coupled Restriction En- zyme Digestion and Random Amplification (CRED-RA) technique. The results suggested that hybrids are more re- sistant to density-related methylation alterations in com- parison to their parental inbreds. KEY WORDS: Heterosis; Methylation; Stress; CRED-RA. INTRODUCTION Heterosis is a genetic phenomenon, in which hybrids manifest superiority over the inbred parental genotypes for several quantitative charac- ters including yield. While plant breeders and agronomists achieved an impressive increase in maize yield utilizing heterosis, the biological basis of the phenomenon remains unknown. Previous at- tempts to understand physiological and biochemical aspects of heterosis demonstrated that maize hy- brids possess superior physiological and biochemi- cal properties than those of the parental lines (for review see T SAFTARIS , 1995). Farmers prefer F1 hy- brids for their high and stable yield while growing in different fields and in different years. Genetic sta- bility (homeostasis) refers to reduced genotype X environment interaction, particularly under stress conditions. The selection of adapted single crosses with high yield and high stability in high planting density has been responsible for the consistent in- crease in maize yields in USA since their introduc- tion in the early 1960s (D UVICK , 1997; F ASOULA and F ASOULA , 1997; J ANICK , 1998; T SAFTARIS and P OLIDOROS , 2000). High planting density is considered as a stress condition and it is worthy to examine the pa- rameters involved in hybrid resistance to density-in- duced stress. Research performed in different laboratories clearly suggests the significance of regulation of gene expression in manifestation of complicated phenomena such as heterosis (T SAFTARIS and P OLI - DOROS , 1993; DE V IENNE et al ., 1996; T SAFTARIS and K AFKA , 1998; S ONG and M ESSING , 2003; W U et al ., 2003). One mechanism involved in regulation of gene expression is DNA methylation. Nuclear DNA
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 09/13/2010 for the course DGPB 024e taught by Professor Alexiospolidoros during the Spring '10 term at Aristotle University of Thessaloniki.

Page1 / 6

10-Maydica Tani - Maydica 50 (2005): 19-23 DNA METHYLATION...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online