This study aimed to investigate the impact of cold stress and priming on photosynthesis in the early development of maize and soybean, crops with diverse photosynthetic pathways. The main objectives ...were to determine the effect of cold stress on chlorophyll
fluorescence parameters and spectral reflectance indices, to determine the effect of cold stress priming and possible stress memory and to determine the relationship between different parameters used in determining the stress response. Fourteen maize inbred lines and twelve soybean cultivars were subjected to control, cold stress, and priming followed by cold stress in a walk-in growth chamber. Measurements were conducted using a portable fluorometer and a handheld reflectance instrument. Cold stress induced an overall downregulation of PSII-related specific energy fluxes and efficiencies, the inactivation of RCs resulting in higher energy dissipation, and electron transport chain impairment in both crops. Spectral reflectance indices suggested cold stress resulted in pigment differences between crops. The effect of priming was more pronounced in maize than in soybean with mostly a cumulatively negative effect. However, priming stabilized the electron trapping efficiency and upregulated the electron transfer system in maize, indicating an adaptive response. Overall, this comprehensive analysis provides insights into the complex physiological responses of maize and soybean to cold stress, emphasizing the need for further genotype-specific cold stress response and priming effect research.
Linking biochemistry and genetics of tolerance to osmotic stress is of interest for understanding plant adaptations to unfavorable conditions. The aims of this study were to investigate the ...variability in responses of panel of elite maize inbred lines to water withholding for stress-related traits through association study and to identify pathways linked to detected associations for better understanding of maize stress responses. Densely genotyped public and expired Plant Variety Protection Certificate (ex-PVP) inbred lines were planted in controlled conditions (16-h/8-h day/night, 25°C, 50% RH) in control (CO) and exposed to 10-day water withholding (WW). Traits analyzed were guaiacol peroxidase activity (GPOD), total protein content (PROT), lipid peroxidation (TBARS), hydrogen peroxide accumulation (H
2
O
2
), proline accumulation (proline), and current water content (CWC). Proline accumulation was found to be influenced by H
2
O
2
and TBARS signaling pathways acting as an accumulation-switching mechanism. Most of the associations detected were for proline (29.4%) and TBARS (44.1%). Gene ontology (GO) enrichment analysis showed significant enrichment in regulation of integral membrane parts and peroxisomes along with regulation of transcription and polysaccharide catabolism. Dynamic studies involving inbreds with extreme phenotypes are needed to elucidate the role of this signaling mechanism in regulation of response to water deficit.
Genomic prediction accuracy (r_MP) is affected by many factors, such as the trait heritability, training population size and structure, and the number of markers. This study’s objective was to ...investigate the factors associated with r_MP for the ear height and the plant height in two planting densities in testcrosses of maize (Zea mays L.) IBM population. Genetic correlations between the training and validation populations were calculated. The high heritability estimates and correlations between the traits were observed. The non-zero estimates of r_MP for all trait-density combinations implied an efficiency of genomic selection. The lower than expected values of genetic correlations were observed between the training and validation populations. However, a strong correlation was observed between a genetic correlation of training and the validation population and r_MP in all three sizes of training populations assessed (20-40%, 40-60%, and 60-80%), suggesting that the size of the training population can be kept low by an appropriate selection while maintaining a high r_MP. Further studies of relationships between the training and validation populations with larger effective population sizes are suggested, as reducing the size of training population while maintaining a high r_MP can facilitate a more effective allocation of resources in a maize breeding program.
The seedling stage has received little attention in maize breeding to identify genotypes tolerant to water deficit. The aim of this study is to evaluate incorporation of seed weight (expressed as ...hundred kernel weight, HKW) as a covariate into genomic association and prediction studies for three biomass traits in a panel of elite inbred lines challenged by water withholding at seedling stage.
109 genotyped-by-sequencing (GBS) elite maize inbreds were phenotyped for HKW and planted in controlled conditions (16/8 day/night, 25 °C, 50% RH, 200 µMol/m
/s) in trays filled with soil. Plants in control (C) were watered every two days, while watering was stopped for 10 days in water withholding (WW). Fresh weight (FW), dry weight (DW), and dry matter content (DMC) were measured.
Adding HKW as a covariate increased the power of detection of associations in FW and DW by 44% and increased genomic prediction accuracy in C and decreased in WW.
Seed weight was effectively incorporated into association studies for biomass traits in maize seedlings, whereas the incorporation into genomic predictions, particularly in water-stressed plants, was not worthwhile.
The in vivo haploid induction has been widely applied to the maize breeding in recent decades, but it has not been used in the breeding programs in the Republic of Croatia by now. This study's ...objectives were to examine the haploid induction rates in the Croatian germplasm and to evaluate the properties of the D0 haploids, which are essential for a successful implementation of this method in breeding. The in vivo haploid induction was performed on 11 single-cross hybrids using the Zarodyshevy Marker Krasnodarsky (ZMK) inducer, and colchicine was used as a chromosome doubling agent. Emergence, misclassification rate, colchicine treatment survival, chromosome doubling rate and self-pollination success were examined in the D0 generation. The haploid induction rates ranged from 6.9 to 15.8%, which is consistent with the average induction rates characteristic of the ZMK inducer and the other modern ones. Significant differences were found among the populations of D0 haploids for all tested properties, except for self-pollination success. On average, the misclassification rates were lower, and the seedling survival rates were higher than those reported in other studies, indicating a possibility of a successful application of the doubled haploid method in maize breeding.
Indukcija haploida in vivo posljednjih se desetljeća sve više primjenjuje u oplemenjivanju kukuruza, ali se dosad nije koristila u oplemenjivačkim programima u Republici Hrvatskoj. Ciljevi ovoga istraživanja bili su utvrditi relativne frekvencije induciranih haploida kod germplazme koja se upotrebljava u domaćim oplemenjivačkim programima i ispitati svojstva haploida generacije D0 koja su važna za uspješnu primjenu ove metode u oplemenjivanju. Indukcija haploida in vivo obavljena je na 11 jednostrukih hibrida pomoću induktora ZMK, a za udvostručenje kromosoma korišten je kolhicin. U generaciji D0 ispitana su svojstva nicanja, pogrešne klasifikacije, preživljavanja tretmana kolhicinom, udvostručenja kromosoma i uspješnosti izvođenja samooplodnje. Relativna frekvencija haploida kretala se od 6,9 do 15,8%, što je usporedivo s prosječnim stopama indukcije specifičnim za induktor ZMK i druge moderne induktore. Statistički značajne razlike pronađene su između populacija haploida D0 za sva ispitana svojstva, osim za uspješnost izvođenja samooplodnje. U prosjeku, stope pogrešne klasifikacije bile su niže, a stope preživljavanja tretmana kolhicinom više u odnosu na one zabilježene u drugim istraživanjima, što ukazuje na mogućnost uspješne primjene metode udvostručenih haploida u oplemenjivanju.
Photosynthesis is a vital process in plant physiology. Performance index is an indicator of plant vitality and is used as a main parameter in chlorophyll fluorescence measurements. Plant density is ...an important factor in maize production that can affect grain yield. Objective of this paper was to estimate the effect of plant density on agronomic traits and photosynthetic efficiency in the maize IBM population. The results showed a decrease in grain yield per plant basis (20 plants per plot) in higher plant density (normal density - 3.88 kg per plot, high density - 2.95 kg per plot) and an increase in grain yield per unit area (yield/ha) in higher plant density (normal density - 11.03t ha-1, high density - 13.64 t ha-1). Performance index was decreased in higher plant density (normal density - 5.31, high density - 4.95). Statistical analysis showed highly significant effect (p<0.001) of density on performance index and highly significant effects (p<0.001) of plant density and genotype on maize yield. Low positive correlation was observed between grain yield per plot and performance index (r = 0.36, p<0.001).
This paper aims to trigger discourse about the emergence of a new type of social scientific model - Exploratory Models - which draw on Big Data, computer modeling and interdisciplinary research to ...tackle complex social scientific processes. First, we define Exploratory Models referring to Batty and Morgan and Morrison. We then present changes to the traditional modeling paradigm. We show how Exploratory Models circumvent challenges related to the idiosyncracy, self-reflexivity and acceleration of social phenomena, which limit predictive effectiveness of traditional models. We show that Exploratory Models are better equipped to tackle complex problems due to their capacity to process heterogeneous datasets. Having established that Exploratory Models are predominantly problem- and data-driven, we emphasize that scientific theory is indispensable to their progress. Finally, the development of an integrative platform is suggested as a way of maximizing the benefits of this approach. Discussion concludes by flagging areas for further research.
Here we describe the results of the detailed array-based genotyping obtained
by using the Illumina MaizeSNP50 BeadChip of eleven inbred lines belonging to
different heterotic groups relevant for ...maize breeding in Southeast Europe -
European Corn Belt. The objectives of this study were to assess the utility
of the MaizeSNP50 BeadChip platform by determining its descriptive power and
to assess genetic dissimilarity of the inbred lines. The distribution of the
SNPs was found not completely uniform among chromosomes, but average call
rate was very high (97.9%) and number of polymorphic loci was 33200 out of
50074 SNPs with known mapping position indicating descriptive power of the
MaizeSNP50 BeadChip. The dendrogram obtained from UPGMA cluster analysis as
well as principal component analysis (PCA) confirmed pedigree information,
undoubtedly distinguishing lines according to their background in two
population varieties of Reid Yellow Dent and Lancaster Sure Crop.
Dissimilarity analysis showed that all of the inbred lines could be
distinguished from each other. Whereas cluster analysis did not definitely
differentiate Mo17 and Ohio inbred lines, PCA revealed clear genetic
differences between them. The studied inbred lines were confirmed to be
genetically diverse, representing a large proportion of the genetic variation
occurring in two maize heterotic groups.
nema
Genomic prediction accuracy (r_MP) is affected by many factors, such as the trait heritability, training population size and structure, and the number of markers. This study’s objective was to ...investigate the factors associated with r_MP for the ear height and the plant height in two planting densities in testcrosses of maize (Zea mays L.) IBM population. Genetic correlations between the training and validation populations were calculated. The high heritability estimates and correlations between the traits were observed. The non-zero estimates of r_MP for all trait-density combinations implied an efficiency of genomic selection. The lower than expected values of genetic correlations were observed between the training and validation populations. However, a strong correlation was observed between a genetic correlation of training and the validation population and r_MP in all three sizes of training populations assessed (20-40%, 40-60%, and 60-80%), suggesting that the size of the training population can be kept low by an appropriate selection while maintaining a high r_MP. Further studies of relationships between the training and validation populations with larger effective population sizes are suggested, as reducing the size of training population while maintaining a high r_MP can facilitate a more effective allocation of resources in a maize breeding program.
Mnogi faktori, kao što su heritabilnost svojstva, veličina i struktura radne populacije i broj markera, utječu na efikasnost genomskih predviđanja (r_MP). Cilj ovoga rada bio je ispitati faktore povezane s〖 r〗_MP za visinu klipa i visinu biljke u dvije gustoće sjetve kod test-križanaca IBM populacije kukuruza (Zea mays L.). Izračunane su genetske korelacije između radne i validacijske populacije. Dobivene su visoke procjene heritabilnosti i korelacije između svojstava. Procjene r_MP bile su različite od nule za sve kombinacije svojstvo -gustoća. što ukazuje na efikasnost genomske selekcije. Vrijednosti genetskih korelacija između radne i validacijske populacije bile su niže od očekivanih. Međutim, jaka korelacija dobivena je između genetske korelacije radne i validacijske populacije i r_MP za sve tri veličine radne populacije (20-40%, 40-60% i 60-80%), što ukazuje da se uz odgovarajuću selekciju veličina radne populacije može održati niskom zadržavajući visoku vrijednosti〖 r〗_MP-a . Potrebna su daljnja istraživanja odnosa između radne i validacijske populacije s većom efektivnom veličinom populacije jer smanjivanje veličine radne populacije, uz održavanje visoke vrijednosti〖 r〗_MP-a može omogućiti učinkovitiju alokaciju resursa u oplemenjivačkome programu kukuruza.
The western corn rootworm (Diabrotica virgifera virgifera LeConte; WCR) is
the most destructive maize pest in the USA, and one of the most dangerous
pests in Europe. In just over a decade from the ...introduction it became one
of the most serious pests in Croatia. Native resistant cultivars could be an
efficient strategy for WCR control. Although research in WCR host plant
resistance has continuously been conducted for over 70 years, no resistant
maize hybrid is commercially available today. The aim of this study was to
evaluate resistance traits in the maize IBM intermated recombinant inbred
lines (IRILs), and detect QTLs associated with resistance to WCR herbivory.
Total of 207 recombinant inbred lines were phenotyped for standard WCR
resistance traits. Several associated QTLs were detected on chromosomes 1,
5, 6, 8, 9, and 10. QTLs on chromosomes 1 (6.41 % variance explained), and 6
(9.26 % variance explained) were mapped in regions harboring genes connected
with plant defense against herbivory. Detected QTLs provide relevant
guidelines for future research on WCR resistance in maize.
nema
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