Reference "The complete sequence of 340 kb of DNA around the rice Adh1-adh2 region reveals interrupted colinearity with maize chromosome 4"

Reference ID

4486

Title

The complete sequence of 340 kb of DNA around the rice Adh1-adh2 region reveals interrupted colinearity with maize chromosome 4

Source

The Plant cell, 2000, vol. 12, pp. 381-391

Authors (5)

Tarchini-R	Biddle-P
Wineland-R	Tingey-S
Rafalski-A

Abstract

A 2.3-centimorgan (cM) segment of rice chromosome 11 consisting of 340 kb of DNA
sequence around the alcohol dehydrogenase Adh1 and Adh2 loci was completely
sequenced, revealing the presence of 33 putative genes, including several
apparently involved in disease resistance. Fourteen of the genes were confirmed
by identifying the corresponding transcripts. Five genes, spanning 1.9 cM of the
region, cross- hybridized with maize genomic DNA and were genetically mapped in
maize, revealing a stretch of colinearity with maize chromosome 4. The Adh1 gene
marked one significant interruption. This gene mapped to maize chromosome 1,
indicating a possible translocation of Adh1 after the evolutionary divergence
leading to maize and sorghum. Several other genes, most notably genes similar to
known disease resistance genes, showed no cross-hybridization with maize genomic
DNA, suggesting sequence divergence or absence of these sequences in maize,
which is in contrast to several other well-conserved genes, including Adh1 and
Adh2. These findings indicate that the use of rice as the model system for other
cereals may sometimes be complicated by the presence of rapidly evolving gene
families and microtranslocations. Seven retrotransposons and eight transposons
were identified in this rice segment, including a Tc1/Mariner-like element,
which is new to rice. In contrast to maize, retroelements are less frequent in
rice. Only 14.4% of this genome segment consist of retroelements. Miniature
inverted repeat transposable elements were found to be the most frequently
occurring class of repetitive elements, accounting for 18.8% of the total
repetitive DNA.