Heterosis: Complementation by Mitochondria

Abstract

Many (but not all) hybrids between two genetic pure lines show heterosis; that is the hybrids grow more rapidly or larger than the parental pure lines. The mechanism is not known. Two corn crosses were studied. In one hybrid known to exhibit heterosis, the mitochondria and an artificial 1:1 mixture of parent mitochondria showed heterosis with respect to oxidation and phosphorylation. In the other cross, neither the hybrid plant, its mitochondria, nor the mixture of parent mitochondria showed heterosis.

Heterosis Is a Systemic Property Emerging From Non-linear Genotype-Phenotype Relationships: Evidence From in Vitro Genetics and Computer Simulations

“…Despite the multiple cases where the bases of heterosis have been clarified, some authors have been searching for a “unifying principle” (Birchler et al, 2003 ), such as genome-wide changes in DNA methylation (Tsaftaris and Polidoros, 1999 ; Shen et al, 2012 ), small RNA expression and epigenetic regulation (Ha et al, 2009 ; Groszmann et al, 2011 ; Chen, 2013 ), reduced metabolic cost of protein recycling in hybrids (Goff, 2011 ), gene dosage effects in macro-molecular complexes (Veitia and Vaiman, 2011 ), enhanced metabolic efficiency due to weak co-aggregation of allozymes (Ginn, 2017 ), mitochondrial complementation (McDaniel and Sarkissian, 1966 ; Srivastava, 1981 ) and phytohormonal expression (Rood et al, 1988 ). These molecular processes may indeed distinguish heterozygotes from homozygotes, but if they were the general hidden causes of heterosis, correlations between levels of heterosis for different traits would be observed, and this has never been reported so far (Flint-Garcia et al, 2009 ; Kaeppler, 2012 ).…”

The possible use of mitochondrial complementation as an indicator of yield heterosis in breeding hybrid wheat

“…Until the discovery of the phenomenon of mitochondrial complementation (MCDANIEL and SARKISSIAN, 1966), this necessitated producing sufficient quantities of the hybrid varieties to allow comparative yield trials to be carried out. It has been shown, however, that in maize (SARKISSIAN and SRIVA-STAVA, 1967), wheat (SARKISSIAN and SRIVASTAVA, 1969a) and barley (MCDANIEL, 1970) heterosis for seedling characters in F1 hybrids can be correlated with the mitochondrial activity of 1 : 1 mixtures of mitochondria extracted from the parental lines.…”

Molybdenum Uptake and Nitrate Reductase Activity in Sorghum (Sorghum bicolor L. Moench). Evidence for Heterosis

“…It is well established that the abihty of plant roots selectively to absorb nutrients is a property which is genetically controlled, and thus differs with species and cultivars (EPSTLIN and JF.FFERIES 1964, NiELSLN and B.\RBLR 1978, FRICK and BAU.MAN 1979. Furthermore, hybrid vigour has been recorded for many traits like oxidative phosphorylation (MCDANIEL and SARKISSIAN 1966), nitrogen metabolism {SCHRADER et al 1966, WARNER ct al. 1969, nucleic acid synthesis (CHERRY et al 1961), and other enzyme activities (HANSON et al, 1960).…”