GENOMIC RELATIONSHIPS BETWEEN TWO SPECIES OF TURNERA HEXAPLOID, T. ORIENTALIS AND T. VELUTINA, AND A DIPLOID, T.GRANDIFLORA (TURNERACEAE SERIES TURNERA)

Abstract

We hybridized two hexaploid species (2n=6x=30) T. orientalis and T. velutina and one diploid species (2n=2x=10), T. grandiflora. These species had regular meiosis forming 15 II the hexaploids and 5 11 the diploid. One hexaploid, 2n=6x=30 (T. orientalis x T. velutina), one pentaploid, 2n=5x=25 (T. orientalis x T. grandiflora) and one tetraploid, 2n=4x=20 (T. velutina x T. grandiflora) hybrids were obtained and studied cytologically to deter ine their genomic relationships. Meiotic behavior in the T. orientalis x T. velutina hybrid was very irregular, with many laggard chromosomes and bridges at AI and AII. Mean pairing relationships were 10,38 I,9,66 II,0,07III and 0,03 IV. The hybrid T. orientalisx T. grandiflora presented irregular meiosis. Mean pairing relationships were 14,66 I and 5,16 II. T. velutina x T. grandiflora presented the most irregular meiosis, with mean pairing relationships of 6,94 I, 6,42 II an 0,05 IV. The three hybrids were sterile. The genome constitution of T. orientalis is AºAºBBBºBº and of T. grandiflora is Cg Cg. On the basis of chromosome associations in the hybrids, we propose the genomic formula AAAvAvCvCv for T. velutina. One genome of T. orientalis is similar to one of the three genomes of T. velutina. The latter species shows one genome similar to the genome of T. grandiflora. Both T. orientalis and T. velutina are segmentary alohexaploids