| dc.description.abstract | The potential for hybridization between cultivated species and their weedy relatives poses agronomic and environmental concerns. Sorghum bicolor (sorghum), one of the most widely cultivated crops in Texas, is a prime example of a crop that has a weedy relative, S. halepense (johnsongrass), capable of exchanging genetic information. Previous crosses (sorghum as the female parent) have shown that the resulting triploid progenies typically collapse and only few of them develop into mature seed, whereas the majority of successful hybridizations involve tetraploid progenies, suggesting the production of 2n female gametes in sorghum. However, little is known on the effect of sorghum parental genotype and cytoplasmic male sterility type on 2n female gamete production in sorghum and consequently the frequency of hybridization. Furthermore, pollen fertility in sorghum (as a female parent) is expected to create a competitive environment where the johnsongrass pollen would have to outcompete the sorghum pollen, further reducing hybridization potential. The objectives of this research were to 1) determine the frequency of 2n female gamete production in sorghum and hybridization with johnsongrass (male parent) by sorghum parental genotype (12 lines) and cytoplasmic male sterility (CMS) type (A1, A2, and A3) under field conditions; and 2) quantify the frequency of hybridization between 12 different male-fertile sorghum parental genotypes (female) and johnsongrass under field conditions. Hybridization rates were as high as 1.28% under self-sterility (within the A1 CMS type, which is commonly used in breeding) and 0.045% under self-fertility across the 12 sorghum genotypes studied. Genotype*sterility type interactions were also significant, with the greatest hybridization rates reaching at 2.2% in A3.Tx623. The knowledge generated from this study will be helpful for developing gene flow mitigation strategies. | en |
