2019 ASHS Annual Conference

Hydrangea macrophylla is a popular floricultural and garden plant and many new cultivars have been introduced to the market each year. To better figure out their genetic variation and molecular links to their morphological characteristics, we selected six ISSR primers from our 96-screened primers to investigate the association of molecular markers and morphological traits. Eighty bands were produced from these six primers and average bands per primer were about 14. Among them, fifty-four bands were polymorphic bands, which accounted for 67.5% of total bands. Hydrangea macrophylla ‘Greenmentle’ is a bud mutation from H. macrophylla ‘Goliath’ with greenish tepals. Among the 61 bands, there were 18 unique ISSR markers to distinguish greenish to pink or blue tepals, which indicated that the color changes of tepals should be detectable using ISSR markers. In term of inflorescence types, we observed ‘Twist-N-Shout’ had both mop-head and lace cap inflorescence on the same plant. ISSR markers revealed that this plant was identical with other regular ‘Twist-N-Shout’ Individuals. Double flowers (multiple layers of tepals) had significant different from ISSR markers when compared to single flowers. From 79 bands amplified for both single flowered ‘Goliath’ and double flowered ‘Izu No Hana’, only 32 shared bands. Golden leaved mutation had several distinguished bands compared to the green leaf cultivar. ISSR markers provide useful molecular information among the cultivars of bigleaf hydrangea, which can potentially lead to the link between morphological characteristics to their gene(s).