Morphologic and Isozyme Variation in Barnyardgrass (Echinochloa) Weed Species

Abstract

Mature seed samples from 35 populations ofEchinochloawere collected in fields of the Eastern Iberian Peninsula and evaluated for nine morphologic traits. Four kernels per population were separately assayed for four isozyme systems. Genetic variability components were studied by correspondence analysis and chi-square distance using the isozyme pattern as variables. Genetic uniformity was found within populations as would be expected from their autogamous mating system. Intraspecific isozyme variability covered a wide spectrum, from none inE. colonumto very high inE. oryzoides. All the populations ofE. colonumclustered together based on morphometric and isozymatic characters, and also those ofE. oryzicola, but were distinct from the populations of all other species. Populations ofE. crus-galli, E. hispidula, andE. oryzoidesclustered within species based on morphology, but did not cluster based on isozymatic characters, being mixed in the isozymatic dendrogram. Our results support the hypothesis thatE. hispidulaandE. oryzoidesare infraspecific taxa ofE. crus-galli. The large between-population genetic variability may explain the differential response to herbicides within a given species and indicate that weed specialists should study the differences in response to a wide spectrum ofEchinochloapopulations to several herbicides instead of testing many plants from a small number of populations.

Cytogenetic Studies on Two Wild Species of Genus <i>Echinochloa</i> P. Beauv. from Saudi Arabia

“…This finding was found in contrast with that previously recorded by Hilu (1994) and Asins et al (1999), who stated the hexaploid nature of the species (2n=54). Genetic stability of the species directly affects seed set, recording high productivity at open pollination conditions.…”

“…Both species seem in fact based on x=9 which is the most common base chromosome number among the majority of the grass family (Muniyamma 1978, Haroun 1997, Haroun et al 1992, Asins et al 1999, Yabuno 1962, 1984 and many other previous studies.…”

“…This number is most common in tribe panicodeae (Haroun 1991, Yabuno 1962, 1984, Voigt et al 1992, Carretero 1981, Asins et al 1999, Hilu 1994, Michael 2001.…”

“…The plant is an annual or perennial erect grass with or without rhizomes. Around the world many species exhibit low variability and are difficult to distinguish because they tend to integrate (Michael 1983, Asins et al 1999, Roy et al 2000.…”

Comparative analysis of genetic diversity of 8 millet genera revealed by ISSR markers

“…These genetic and morphological differences in the Echinochloa species lead to taxonomic problems. Thus, many studies have attempted to understand the population genetic structures of some Echinochloa species, and have revealed their genetic diversity by using molecular markers (Asins et al, 1999;Roy et al, 2000;Rutledge et al, 2000;Tasrif et al, 2004;Altop and Mennan, 2011;Nozawa et al, 2006;Danquah et al, 2002). As with previous studies, the Echinochloa species in the present study were differentiated, and might confirm the theory of Yabuno (1966) and Scholz (1992), that the weedy Echinochloa crus-galli has its cultivated counterpart Echinochloa esculenta.…”