Description:
Four Medicago species contributed to ALPAX: 1- M. sativa, three alfalfa clones, M8, MBms, and 6-4ms. 2- M. arborea plants, used as pollen parents. M, sativa and M. arborea are perennial and heterozygous tetraploids, 2n=4x=32 (see: Plants MDPI 2:343-353, on the web). 3- M. truncatula, and 4- M. intertexta, both annual and homozygous. The first perennial X annual cross was purple-flowered alfalfa clone 4x MBms X 4x M. truncatula in 2006. The hybrid had variegated flowers due yellow from M. truncatula. Four more hybrids were obtained in crosses of M8 X 4x M. truncatula, identified by yellow flower color from M. truncatula (Medicago Genetic Reports vol. 13, 2013; www.medicago-reports.org). Since the 2013 report, these hybrids were intercrossed, advanced to F3, and used in several experiments. In 2017, a self-sterile, light yellow flowered F3 plant was selected and crossed with M. intertexta. Two hybrids were obtained with dark yellow flower color and robust vigor from M. intertexta. These hybrids contained fractions of genomes from three species: M. sativa, M. truncatula, and M. intertexta, with M. sativa retaining the largest fraction. The next cross added the M. arborea species to ALPAX. This cross involved a hybrid derivative of alfalfa X M. arborea, named ‘Alborea’ (see: Agricultural Science 28: 40-46, 2016). A self-sterile Alborea plant from PI 690775 was used as seed parent, and pollinated with M. intertexta pollen. One robust hybrid was obtained with strong yellow flower color from M. intertexta. Over the years, these materials with four Medicago species in their pedigree, were crossed in various combinations for experiments, and studied in segregating generations for traits discussed in the following narrative. ALPAX is remnant seed of these experiments.