Ploidy Level and Genetic Diversity in the Genus Paspalum, Group Disticha

Abstract

The importance of the warm‐season grass Paspalum vaginatum Sw. lies in its salt tolerance and its ability to serve as forage, ground cover for erosion control, and turf for sport surfaces in vulnerable areas in the tropics and subtropics. We conducted DNA content measurements using flow cytometry and diversity analyses using 43 simple sequence repeat (SSR) markers in a set of 97 Paspalum group Disticha accessions to resolve the relationship between the two group Disticha species, P. vaginatum Sw. and P. distichum L., and determine their ploidy level, genetic diversity, population structure, and distribution history. Using glume pubescence as a distinguishing characteristic, P. vaginatum accessions were largely diploid and P. distichum accessions largely polyploid, although exceptions were identified in both species. Transferability of genomic P. vaginatum SSRs to P. distichum confirmed the close genetic relationship between the two species. Similarity in SSR allele sizes between the two species may be an indication of gene flow. Population structure analyses grouped the germplasm into three subpopulations. One subpopulation consisted of accessions with mixed leaf texture, mixed glume pubescence phenotypes, and mixed ploidy levels. The other two subpopulations contained only diploid members with a typical P. vaginatum turf phenotype. Our data bring into question the distinguishing characteristics of P. distichum and P. vaginatum and whether they should be considered the same species. We also make some strategic recommendations for new collections and accession maintenance.

Measurement of Genetic Diversity of Chinese Seashore Paspalum Resources through Morphological and Sequence-related Amplified Polymorphism Analysis

“…Paspalum vaginatum has typically been reported as diploid, and the chromosome number is 2n = 2x = 20 (Duncan and Carrow, 2000;Echarte and Clausen, 1993). However, certain P. vaginatum accessions are polyploid (Eudy et al, 2017;Hojsgaard et al, 2009). In the present study, most Chinese seashore paspalum resources had larger organs than those of the U.S. cultivars.…”

The Halophyte Seashore Paspalum Uses Adaxial Leaf Papillae for Sodium Sequestration

“…They have historically been distinguished by the presence of glabrous (P. vaginatum) or pubescent glumes (P. distichum) (Echarte, 1993). 'PI 299042' was shown by Eudy et al (2017) to have glabrous glumes, as did 'HI10' and '509018-3', classifying these accessions as P.…”

“…vaginatum, and 'Spence' and 'Tropic Shore' have been classified as P. distichum, genotyping analysis with simple sequence repeat (SSR) markers showed that the three accessions belonged to the same genetic subpopulation within group 'Disticha'. 'HI10' belonged to a different genetic population group (Eudy et al, 2017). Papillae were comparable in size in 'PI 299042'…”

“…Papilla size varied significantly across accessions. 'HI10', 'KC9' and '509018-3, three turf-type P. vaginatum accessions with a fine leaf texture that belonged to the same genetic subpopulation based on 43 simple sequence repeat (SSR) markers (Eudy et al, 2017), had similarly sized large papillae, while 'Spence', a P. distichum accession, which belonged to a different genetic subpopulation, had broad leaves and significantly smaller papillae (Supplemental Fig. S2A S5).…”

“…Here, we studied the leaf structure and Na + sequestration in 'HI10', a P. vaginatum accession, and 'Spence', a Paspalum distichum accession. P. vaginatum and P. distichum are closely related (and possibly the same species; Eudy et al, 2017), and constitute group 'Disticha' in the tribe Paspaleae. P. distichum is less salt tolerant than P. vaginatum and is typically found in freshwater habitats (Leithead et al, 1971).…”