Nilda Burgos | University of Arkansas (original) (raw)

Papers by Nilda Burgos

The following companies provided financial support and chemicals used in the studies: AgrEvo,

Research Series - Arkansas Agricultural Experiment Station, 2000

Genes

Echinochloa colona and other species in this genus are a threat to global rice production and foo... more Echinochloa colona and other species in this genus are a threat to global rice production and food security. Quinclorac, an auxin mimic, is a common herbicide for grass weed control in rice, and Echinochloa spp. have evolved resistance to it. The complete mode of quinclorac action and subsequent evolution of resistance is not fully understood. We analyzed the de novo transcriptome of multiple-herbicide-resistant (ECO-R) and herbicide-susceptible genotypes in response to quinclorac. Several biological processes were constitutively upregulated in ECO-R, including carbon metabolism, photosynthesis, and ureide metabolism, indicating improved metabolic efficiency. The transcriptional change in ECO-R following quinclorac treatment indicates an efficient response, with upregulation of trehalose biosynthesis, which is also known for abiotic stress mitigation. Detoxification-related genes were induced in ECO-R, mainly the UDP-glycosyltransferase (UGT) family, most likely enhancing quinclorac...

Weed Science

Weedy rice (Oryza sativa f. spontanea or O. sativa complex) has become a severe threat to Malaysi... more Weedy rice (Oryza sativa f. spontanea or O. sativa complex) has become a severe threat to Malaysian rice (Oryza sativa L.) granaries after the direct-seeding method of rice cultivation was introduced in the late 1980s. Since then, researchers have studied the biology and ecology of weedy rice and espoused the evolutionary theory of the origin of Malaysian weedy rice. This review paper aimed to synthesize the body of knowledge about weedy rice and the evolution of herbicide-resistant (HR) weedy rice in Malaysia. The imidazolinone (IMI) herbicide component of the Clearfield® Production System (CPS) rice package is among the most effective tools for weedy rice control. However, dependence solely on this technology and farmers’ ignorance about the appropriate use of IMI herbicides with the CPS rice package have resulted in the evolution of IMI-resistant (IMI-R) weedy rice. This has reduced the efficacy of IMI herbicides on weedy rice, ultimately nullifying the benefit of CPS rice in aff...

Herbicidal weed control is economically important for production of cotton. Field experiments are... more Herbicidal weed control is economically important for production of cotton. Field experiments are conducted annually in Arkansas to evaluate the activity of developmental and commercial herbicides for selective control of weeds in cotton. These experiments serve both industry and Arkansas agriculture by providing information on the selectivity of herbicides still in the developmental stage and by comparing the activity of these new herbicides with that of recommended herbicides. The research reported herein is a compilation of data from experiments conducted by four of the state’s agronomic researchers responsible for weed control in cotton. Jim Barrentine, Marilyn McClelland, and Nilda Burgos are located at the Main Experiment Station, Fayetteville, and conduct research at Fayetteville, at the Cotton Branch Experiment Station, Marianna, and at Isgrig farm at Lonoke. Ken Smith is located at the Southeast Research and Extension Center in Monticello and conducts research at the Southe...

Pakistan Journal of Botany, 2017

Littleseed canarygrass (Phalaris minor) infests wheat and other winter crops in Pakistan and many... more Littleseed canarygrass (Phalaris minor) infests wheat and other winter crops in Pakistan and many other countries. Studies were conducted in Pakistan to confirm littleseed canarygrass resistance to fenoxaprop-P-ethyl and to appraise the efficacy of other postemergence herbicides against this grassy weed. A field survey was conducted to collect putative fenoxaprop-resistant seeds from various districts of the central Punjab in March 2015. Dose-response assays were conducted in the greenhouse to confirm resistance to fenoxaprop. The response of fenoxaprop-resistant littleseed canarygrass to diverse herbicide molecules like clodinafop-propargyl, metribuzin, pinoxaden, and sulfosulfuron was also evaluated in further dose response bioassays. All accessions manifested variable resistance to fenoxaprop, which ranged from 2.52- to 6.00-fold. The resistant accessions also showed low-level cross-resistance (two-fold) to clodinafop. Metribuzin, pinoxaden, and sulfosulfuron were still effective...

Agriculture, 2020

Rice is the staple food for about half of the world population. Rice grain yield and quality are ... more Rice is the staple food for about half of the world population. Rice grain yield and quality are affected by climatic changes. Arguably, rice cultivars’ genetic diversity is diminished from decades of breeding using narrow germplasm, requiring introgressions from other Oryza species, weedy or wild. Weedy rice has high genetic diversity, which is an essential resource for rice crop improvement. Here, we analyzed the phenotypic, physiological, and molecular profiles of two rice cultivars (IRGA 424 and SCS119 Rubi) and five weedy rice (WR), from five different Brazilian regions, in response to heat and drought stress. Drought and heat stress affected the phenotype and photosynthetic parameters in different ways in rice and WR genotypes. A WR from Northern Brazil yielded better under heat stress than the non-stressed check. Drought stress upregulated HSF7A while heat stress upregulated HSF2a. HSP74.8, HSP80.2, and HSP24.1 were upregulated in both conditions. Based on all evaluated trait...

Weed Research, 2018

Hybridisation between genetically distinct lineages results in increases in overall genetic diver... more Hybridisation between genetically distinct lineages results in increases in overall genetic diversity and is a potential mechanism for the origin and spread of adaptive alleles. Weed and crop hybridisation may result in weedy ecotypes, which have, in addition to classic weedy traits such as seed shattering and long seed dormancy, crop traits that enhance weediness, such as adaptation to field cultivation and harvest strategies. Weedy rice (Oryza sativa) hybridises with cultivated rice and, in the process, may produce new (pink-awned) weedy rice varieties. Pink-awned (PA) weedy rice plants have been observed in rice fields in Arkansas. We explored the genetic relationships between PA weedy rice, crop rice, global rice accessions and other weedy rice ecotypes present in the southern United States. Gene sequencing of 48 sequence-tagged sites (STS loci) revealed a pattern of hybridisation and gene flow between blackhull weedy rice and tropical japonica rice (O. sativa subsp. japonica) cultivars. Our data suggest that PA rice originates from hybridisation between blackhull weedy rice and tropical japonica rice. PA rice offspring segregate phenotypic traits associated with weediness in rice. This segregation could lead to adaptive allele combinations in PA rice, which could potentially move into other weedy rice types through subsequent hybridisation events.

Agriculture, 2018

Resistance to herbicides in Italian ryegrass (Lolium perenne L. ssp. multiflorum (Lam.) Husnot) i... more Resistance to herbicides in Italian ryegrass (Lolium perenne L. ssp. multiflorum (Lam.) Husnot) is an economically important herbicide-resistance issue in world agriculture. Diclofop-resistant ryegrass is the number one weed problem in Arkansas wheat. Field studies were conducted from 2006 through 2008 at Bredlow corner and Fayetteville, Arkansas, USA to determine the effect of herbicide programs consisting of pinoxaden (Axial) alone or in mixtures with preemergence and postemergence herbicides, along with tillage systems, for managing diclofop-resistant Italian ryegrass. Italian ryegrass control, wheat injury, and grain yield were evaluated. A single treatment with pinoxaden alone resulted in 58% ryegrass control and 1488 kg ha −1 grain yield. The best treatment was metribuzin followed by mesosulfuron, which resulted in 2793 kg grain yield ha −1 , a 47% increase compared to pinoxaden alone. In Fayetteville (2006-2007 and 2007-2008), the best treatment was two applications of metribuzin, which yielded about 3700 kg grain ha −1. A single application of pinoxaden resulted in 40% loss of grain yield compared to a single application of flufenacet + metribuzin and almost 50% yield loss compared to sequential application of metribuzin. Yield loss was attributed due to insufficient control of Italian ryegrass. The effect of tillage on Italian ryegrass was inconsistent between years and treatments. In the first year, for example, tillage × herbicide treatments did not differ. In the second and third year, control of Italian ryegrass was better in no-till than in conventional till in both locations. In conclusion, pinoxaden alone could not control diclofop-resistant Italian ryegrass sufficiently. Other herbicide modes of action need to be added to the management program of diclofop-resistant Italian ryegrass, especially one with residual activity such as metribuzin.

Weed Science, 2018

Seed dormancy allows weedy rice (Oryza sp.) to persist in rice production systems. Weedy and wild... more Seed dormancy allows weedy rice (Oryza sp.) to persist in rice production systems. Weedy and wild relatives of rice (Oryza sativa L.) exhibit different levels of dormancy, which allows them to escape weed management tactics, increasing the potential for flowering synchronization, and therefore gene flow, between weedy Oryza sp. and cultivated rice. In this study, we determined the genetic diversity and divergence of representative dormant and nondormant weedy Oryza sp. groups from Arkansas. Twenty-five simple sequence repeat markers closely associated with seed dormancy were used. Four populations were included: dormant blackhull, dormant strawhull, nondormant blackhull, and nondormant strawhull. The overall gene diversity was 0.355, indicating considerable genetic variation among populations in these dormancy-related loci. Gene diversity among blackhull populations (0.398) was higher than among strawhull populations (0.245). Higher genetic diversity was also observed within and amo...

Field Crops Research, 2017

Studies were conducted to determine the impact of introgression of crop alleles into weedy rice p... more Studies were conducted to determine the impact of introgression of crop alleles into weedy rice populations. Seeds of weedy rice accessions collected from Arkansas fields in 11 counties, with a history of Clearfield TM rice production, were planted in 2011 and sprayed twice with imazethapyr (0.071 kg ai ha-1). Survivors were genotyped using an allele-specific PCR assay to detect the presence of resistance-endowing als mutations, S 653 N and G 654 E, in herbicideresistant (HR) weedy rice that could have originated from Clearfield TM cultivars planted in the state. Hybridization between Clearfield TM rice and weedy rice was verified using microsatellite markers RM 215, RM 220, RM 234 and RID12. Two to five HR plants, representing different plant types per accession per replication (698 plants total) were characterized for 16 morphological and biological traits. Seventy-nine percent of accessions were resistant to imazethapyr. The HR weedy rice plants carried the S 653 N mutation and were confirmed as outcrosses with Clearfield TM rice using microsatellite markers. Ten weedy rice accessions (nearly 25% of confirmed outcrosses) harbored multiple alleles from rice cultivars, indicating previous hybridization events with multiple cultivars or outcrossing with weedy rice. The majority of HR weedy rice accessions were similar to cultivated rice in height, culm angle, flag leaf length and width, days to flower, seed shattering and dormancy. Kernels of 20% of the parent weedy rice accessions were segregating for white and red bran color. Two of the parent weedy rice accessions with gold hull were homozygous for white bran and produced progenies with 100% white-bran kernels; thus, weedy rice was no longer exclusively red. Therefore, HR weedy rice outcrosses generally had acquired crop-like traits, which make it easier to deplete from the soil seedbank, but also difficult to scout.

PLOS ONE, 2016

Domestication is the hallmark of evolution and civilization and harnesses biodiversity through se... more Domestication is the hallmark of evolution and civilization and harnesses biodiversity through selection for specific traits. In regions where domesticated lines are grown near wild relatives, congeneric sources of aggressive weedy genotypes cause major economic losses. Thus, the origins of weedy genotypes where no congeneric species occur raise questions regarding management effectiveness and evolutionary mechanisms responsible for weedy population success. Since eradication in the 1970s, California growers avoided weedy rice through continuous flood culture and zero-tolerance guidelines, preventing the import, presence, and movement of weedy seeds. In 2003, after decades of no reported presence in California, a weedy rice population was confirmed in dry-seeded fields. Our objectives were to identify the origins and establishment of this population and pinpoint possible phenotypes involved. We show that California weedy rice is derived from a different genetic source among a broad range of AA genome Oryzas and is most recently diverged from O. sativa temperate japonica cultivated in California. In contrast, other weedy rice ecotypes in North America (Southern US) originate from weedy genotypes from China near wild Oryza, and are derived through existing crop-wild relative crosses. Analyses of morphological data show that California weedy rice subgroups have phenotypes like mediumgrain or gourmet cultivars, but have colored pericarp, seed shattering, and awns like wild relatives, suggesting that reversion to non-domestic or wild-like traits can occur following domestication, despite apparent fixation of domestication alleles. Additionally, these results indicate that preventive methods focused on incoming weed sources through contamination may miss burgeoning weedy genotypes that rapidly adapt, establish, and proliferate. Investigating the common and unique evolutionary mechanisms underlying global weed PLOS ONE |

Planta Daninha, 2011

The continuous use of ALS-inhibiting herbicides has led to the evolution of herbicide-resistant w... more The continuous use of ALS-inhibiting herbicides has led to the evolution of herbicide-resistant weeds worldwide. Greater beggarticks is one of the most troublesome weeds found in the soybean production system in Brazil. Recently, a greater beggarticks biotype that is resistant (R) to ALS inhibitors due to Trp574Leu mutation in the ALS gene was identified. Also, the adaptive traits between susceptible (S) and R to ALS inhibitors biotypes of greater beggarticks were compared. Specifically, we aimed to: (1) evaluate and compare the relative growth rates (RGR) between the biotypes; (2) analyze the seed germination characteristics of R and S biotypes under different temperature conditions; and (3) evaluate their competitive ability in a replacement series study. The experiments were conducted at the University of Arkansas, USA, in 2007 and at Universidade Federal do Rio Grande do Sul (Federal University of Rio Grande do Sul), Brazil, in 2008. Plant proportions for replacement series stud...

Lolium perenne ssp. multiflorum (Italian ryegrass) is a major weed problem in wheat production. B... more Lolium perenne ssp. multiflorum (Italian ryegrass) is a major weed problem in wheat production. Being an obligate outcrossing species, it has a high propensity to evolve resistance to herbicides. This study was conducted to determine the level of resistance and resistance patterns of Italian ryegrass populations in the United States to ACCase- (diclofop and pinoxaden) and ALS (imazamox, mesosulfuron, and pyroxsulam) inhibitors. Dose-response bioassays were conducted on 47 populations from suspect herbicide-resistant fields in the southern United States (Arkansas, Mississippi, Georgia, North Carolina, South Carolina,Virginia), Kansas, and Washington collected between 2008 and 2011 from fields suspected of resistance to ALS inhibitors. Eighty-seven percent of the populations were resistant to diclofop. Eight of the diclofopresistant populations (25%) were also resistant to pinoxaden. Thirty-eight diclofop-resistant populations (81%) were resistant to at least one ALS inhibitor. Thirty...

Weed Technology, 2011

In 2007, populations of Italian ryegrass were observed surviving applications of glyphosate under... more In 2007, populations of Italian ryegrass were observed surviving applications of glyphosate under field conditions in southeast Arkansas. At least 10 reports of Italian ryegrass escaping glyphosate applications followed in subsequent years in Arkansas. These were unconfirmed reports of resistance from county agents, consultants, and farmers. The objectives of this research were to confirm resistance to glyphosate in a suspected resistant population collected in 2007 (Desha 2007) and to determine the level of resistance of a putative glyphosate-resistant population collected in 2009, both from Desha County, AR. Other objectives were to determine the resistance frequency in these populations, to determine whether the 2009 population was also acetolactate synthase (ALS) or acetyl-CoA carboxylase (ACCase-resistant), and to determine the effect on plant size as it relates to dose–response to glyphosate. The Desha, AR, 2007 population exhibited a low level of resistance to glyphosate. The...