Morphological and genetic characteristics of hybrid combinations of Dactylis glomerata.

Six F1 populations derived from crosses among 4 orchardgrass (Dactylis glomerata L.) cultivars were studied by morphological and simple sequence repeat molecular markers to test for hybrid vigor and a correlation between genetic distance and heterosis. Heterosis was observed for days to length of culm, leaf traits, tiller numbers, etc. Significant differences between obverse and inverse crosses were found for eleven traits. A cytoplasmic effect existed for the agronomic traits considered in this study. The correlations between genetic distance and heterosis were investigated by analyzing the performance of 3 crosses. The results showed that genetic distance was significantly correlated with tiller number (r = 0.834) and negatively correlated with length of culm (r = -0.889). However, there was no significant correlation with heterosis for the other traits, including yield; the correlation coefficient were too small to allow prediction of orchardgrass heterosis from the parental genetics.

Identification of orchardgrass (Dactylis glomerata L.) cultivars by using simple sequence repeat markers.

The accurate identification of orchardgrass (Dactylis glomerata L.) cultivars is necessary to ensure purity for consumers, the effective utilization of cultivars, and to protect the intellectual property for breeders. Therefore, this study aimed to use SSR to construct DNA fingerprinting of orchardgrass cultivars. The genetic diversity of 32 orchardgrass cultivars originated from 21 countries, but grown in China, was assessed using a set of 29 SSR markers distributed across 9 linkage groups of the orchardgrass genome. A total of 229 bands were detected, with an average of 7.9 bands per marker. The average polymorphic rate for the species was 92.1%. The polymorphism information content ranged from 0.771 to 0.893. The genetic similarity ranged from 0.55 to 0.84, which confirmed a high level of genetic diversity among orchardgrass cultivars. The unweighted pair-group method, in combination with the arithmetic mean algorithm (UPGMA) dendrogram and principal coordinate analysis, showed a separation of 6 major clusters among 32 cultivars. The number of distinguishable cultivars ranged from 3 to 23, with an average of 12.1 per primer. Moreover, 11 bands that showed stable and repeatable SSR patterns were amplified by A01E14, A01K14, and D02K13. These bands were used to develop the DNA fingerprints for 32 orchardgrass cultivars. In the DNA fingerprints constructed, each cultivar had a unique fingerprinting pattern that was easily distinguished from the others. These results indicate that the SSR marker was polymorphic, and reliable for use in potential large-scale DNA fingerprinting of orchardgrass cultivars.