A proposed mechanism for loss of heterozygosity in rice hybrids |
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| Authors: | Richard R-C Wang Xiaomei Li N Jerry Chatterton |
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| Institution: | (1) Forage & Range Research Laboratory, USDA-ARS, Logan, UT, 84322-6300, U.S.A. |
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| Abstract: | A phenomenon, loss of heterozygosity (LOH), was discovered in hybrid plants involving a selected plant (named AMR) of the
Chinese rice cultivar ‘ZhongxinNo. 1’ as one parent. In these hybrids and some of their progenies, somatic variations were
manifested by molecular genotypes and/or morphological phenotypes in vegetative parts of the same plant. Random amplified
polymorphic DNA (RAPD) markers for the parents have been followed through the F3 generation. RAPD markers were uniformly present or absent in all plants within some or all F2 panicle rows derived from F1 hybrids involving AMR. In contrast, RAPD markers segregated in the Mendelian manner for dominant markers in panicle rows
derived from control hybrids. Certain F2 panicle rows from F1hybrids involving the special rice became fixed for all assayed RAPD markers. Genotype fixation was confirmed by molecular
assays and field observations of the F3 progenies. We propose a new biological mechanism, called ‘assortment mitosis,’ as being responsible for the observed phenomenon.
The use of this mechanism in plant hybrids allows the development of uniform progenies as early as the F2 generation. Therefore, the time required to obtain fixed non-parental type progenies for subsequent performance trials can
be drastically shortened. Utilizing this mechanism in plant breeding represents a new approach and requires the modification
of conventional plant breeding procedures.
This revised version was published online in July 2006 with corrections to the Cover Date. |
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| Keywords: | chromosome assortment homozygosity hybrid LOH mitosis rice |
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