US: Ploidy levels and pollen stainability of Lantana camara cultivars and breeding lines
This study aimed to determine the ploidy level and male fertility of both commercial L. camara cultivars and breeding lines to identify male-sterile cultivars and assess the effectiveness of sterile triploid production in L. camara. A polyploid series was identified among 32 L. camara cultivars and breeding lines. Male fertility, based on pollen stainability, varied widely among the cultivars/breeding lines. Ploidy level was the most important factor determining L. camara pollen stainability/male sterility. On average, diploids exhibited the highest pollen stainability (64.6%) followed by tetraploids (45.1%), pentaploids (34.6%), and hexaploids (18.0%). Triploids showed the lowest pollen stainability (9.3%), suggesting that generating triploids would be an effective genetic approach to producing sterile L. camara and reducing its pollen-mediated invasiveness. Pollen stainability of triploid cultivars, Balandpawn (LandmarkTM Pink Dawn PP15,516), Lemon Drop, Miss Huff, New Gold, New Red Lantana, Red Butler, Red Spread Lantana, Samson Lantana, and Sunset Lantana was consistently below 10%. A number of triploid cultivars had pollen stainability approaching 20% to 30%, indicating a necessity for careful examination and screening of newly produced triploids to ensure high sterility in selected triploids.
Pollen stainability variation was observed within ploidy levels, implying the existence of other genetic and environmental factors that influence the pollen stainability/male fertility of L. camara. Results from this study suggest that there is excellent potential to develop genetically sterile cultivars in L. camara for the U.S. nursery and landscape industry.
Click here to purchase the article at http://hortsci.ashspublications.org.