A survey of apomixis and ploidy levels among Poa L. (Poaceae) using flow cytometry

Poa is a complex genus taxonomically and genetically. As a result, relatively little information exists for this economically important genus with regards to reproductive mode and variability in chromosome number. We examined apomixis frequency and ploidy levels in 83 Poa accessions representing 33 species from the National Plant Germplasm System using fl ow cytometric techniques. In reproductive mode analysis, we analyzed at least three preparations of 50 seeds each from the accessions. In ploidy level analysis, at least three plants of each accession were analyzed. Sixty percent of the species had at least one apomictic or facultative apomictic accession; 40% were sexual. Thirty-three percent of the species had no sexual accessions. Autonomous apomixis was newly identifi ed in P. bactriana and P. bulbosa in addition to it being previously reported in P. nervosa. Poa annua and P. trivialis were identifi ed as obligate sexual, and P. nervosa as obligate apomictic. Two of four P. palustris accessions exhibited facultative apomixis. Ploidy levels among sexually reproducing Poa accessions ranged from 2n = 2x = 14 to 2n = 12x = 84, with most accessions between 2n = 3x = 21 to 2n = 8x = 56. Among apomictic accessions, ploidy levels ranged from 2n = 3x = 21 to 2n = 10x = 70, with most between 2n = 4x = 28 and 2n = 10x = 70. These results emphasize the wide variability in Poa, both among and within species. A.M. Kelley, Seattle, WA; P.G. Johnson, Dep. of Plants, Soils, and Climate, Utah State Univ., 4820 Old Main Hill, Logan, UT 84322-4820; B.L. Waldron and M.D. Peel, USDA-ARS, Forage and Range Research Lab., 690 North 1100 East, Logan, UT 84322-6300. Received 22 Sept. 2008. *Corresponding author ([email protected]). Abbreviations: NPGS, National Plant Germplasm System. Published in Crop Sci. 49:1395–1402 (2009). doi: 10.2135/cropsci2008.09.0553 © Crop Science Society of America 677 S. Segoe Rd., Madison, WI 53711 USA All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Permission for printing and for reprinting the material contained herein has been obtained by the publisher.