生物谷報(bào)道：由孟德?tīng)柺状斡^察到的遺傳原理是足夠清楚的。遺傳信息在生物體的每個(gè)細(xì)胞中都有的染色體所攜帶的DNA中從父輩傳給子輩,，在如線粒體和葉綠體等細(xì)胞器中的輔助基因組中也進(jìn)行著這樣的遺傳信息傳遞,，只是程度小一些,。但對(duì)擬南芥（Arabidopsis thaliana）中發(fā)生回復(fù)突變的hothead基因突變體所做的分析表明,，這些植物能遺傳在父輩染色體中沒(méi)有,、但與祖父或更遠(yuǎn)祖先的染色體中相同的信息,。這可能涉及從一個(gè)RNA存放處傳遞來(lái)的祖先DNA在模板引導(dǎo)下的恢復(fù)，這種RNA存放處就像一個(gè)存放舊網(wǎng)頁(yè)的瀏覽器存放處一樣,。研究這種形式的遺傳是否普遍存在將會(huì)很有趣,。本期封面所示為一株有hothead突變體的花（掃描電子顯微圖片由M. A. Webb提供）。
該文發(fā)表在 Nature 434, 505 - 509 (24 March 2005); doi:10.1038/nature03380
詳細(xì)參加如下：
Genome-wide non-mendelian inheritance of extra-genomic information in Arabidopsis
SUSAN J. LOLLE*, JENNIFER L. VICTOR, JESSICA M. YOUNG & ROBERT E. PRUITT*
Department of Botany and Plant Pathology, Purdue University, 915 W. State Street, West Lafayette, Indiana 47907-2054, USA
* These authors contributed equally to this work
Correspondence and requests for materials should be addressed to R.E.P. ([email protected]).
A fundamental tenet of classical mendelian genetics is that allelic information is stably inherited from one generation to the next, resulting in predictable segregation patterns of differing alleles. Although several exceptions to this principle are known, all represent specialized cases that are mechanistically restricted to either a limited set of specific genes (for example mating type conversion in yeast) or specific types of alleles (for example alleles containing transposons or repeated sequences). Here we show that Arabidopsis plants homozygous for recessive mutant alleles of the organ fusion gene HOTHEAD (HTH) can inherit allele-specific DNA sequence information that was not present in the chromosomal genome of their parents but was present in previous generations. This previously undescribed process is shown to occur at all DNA sequence polymorphisms examined and therefore seems to be a general mechanism for extra-genomic inheritance of DNA sequence information. We postulate that these genetic restoration events are the result of a template-directed process that makes use of an ancestral RNA-sequence cache.
