The role of triploids in the origin and evolution of polyploids of Turnera sidoides complex (Passifloraceae, Turneroideae)

JUAN MANUEL ROGGERO LUQUE; VIVIANA GRISELDA SOLÍS NEFFA; GABRIELA ELIAS; IVANA EVELIN KOVALSKY; SILVIA ANDREA FERNÁNDEZ

JOURNAL OF PLANT RESEARCH

SPRINGER TOKYO

Año: 2017 vol. 131 p. 77 - 89

0918-9440

Abstract Triploids can play an important role in polyploidevolution. However, their frequent sterility is an obstaclefor the origin and establishment of neotetraploids. Here weanalyzed the microsporogenesis of triploids (x=7) and thecrossability among cytotypes of Turnera sidoides, aiming totest the impact of triploids on the origin and demographicestablishment of tetraploids in natural populations. Triploidsof T. sidoides exhibit irregular meiotic behavior. The highfrequency of monovalents and of trivalents with non-convergentorientations results in unbalanced and/or non-viablemale gametes. In spite of abnormalities in chromosome pairingand unbalanced chromosome segregation, triploids arenot completely sterile and yielded up to 67% of viable pollen.Triploids that originated by the fusion of 2n×n gametesof the same taxon showed more regular meiotic behaviorand higher fertility than triploids from the contact zone ofdiploids and tetraploids or triploids of hybrid origin. Thereproductive isolation of T. sidoides cytotypes of differentploidy level is not strict and the ?triploid block? maybe overcome occasionally. Triploids of T. sidoides producediploid and triploid progeny suggesting that new generationsof polyploids could originate from crosses betweentriploids or from backcrosses with diploids. The capabilityof T. sidoides to multiply asexually by rhizomes, wouldenhance the likelihood that a low frequency of neopolyploidscan be originated and maintained in natural populations of T. sidoides