This work aimed to evaluate the drought tolerance of transformed plants of the cultivar BRSMG Curinga that overexpress the rice phospholipase D α1 (OsPLDα1) gene. The productivity of independent transformation event plants of the OsPLDα1 gene was evaluated in an experiment where 19 days of water deficit were applied at the reproductive stage, a very strict growing condition for upland rice. The non-genetically modified cultivar (NGM) under drought treatment reduced productivity by 89% compared with that under irrigated treatment, whereas transformed plants (PLDα1_E2) reduced productivity by only 41%. After the drought treatment, the PLDα1_E2 plants productivity was five times greater than that of the NGM plant. Moreover, no adverse effects on growth and development of the transgenic plants were observed. Seven days after the resumption of irrigation, PLDα1_E2 plants had higher stomatal conductance, greater photosynthetic rate, and transpiration rate than did NGM plants, as well as a higher expression level of the OsPLDα1 gene. A delay in the senescence process was observed in these PLDα1_E2 plants, and this was determined for the recovery of photosynthesis, with greater expression of the Rubisco and lower expression of the SOD. This finding was suggestive of decreased oxidative stress, probably due to gas exchange by the partial closure of the stomata of these transformed plants, which prevented the formation of reactive oxygen species. OsPLDα1 gene overexpression resulted in a reduction in production loss under severe water deficit and revealed a possibility for the development of upland rice cultivars that are more tolerant to extreme drought conditions.
1295RESEARCH P roduction and consumption of white rice (Oryza sativa L.) are prevalent in the world, although the original pigmentation of the pericarp of all rice species is red. The white pericarp, a colorless phenotype, is determined by the rc allele that originated from a loss-of-function mutation at the Rc locus on chromosome 7 in Oryza rufipogon Griffiths-a wild relative of cultivated rice. The red coloration, in turn, is determined by the complementary effect of two genes, Rc and Rd, each one inherited monogenically. The original dominant allele (Rc) interacts with the Rd allele on chromosome 1 to synthesize the proanthocyanidin compound that determines red pericarp pigmentation in rice grains. Specifically, the Rc allele that encodes the basic helix-loop-helix (bHLH) protein is responsible for the accumulation of pigments in the pericarp of brown-colored grains, whereas the Rd allele that encodes the dihydroflavonol-4-reductase (DFR) enzyme is required to increase the content of the pigment, resulting in redcolored grains (Nagao et al., 1957;Furukawa et al., 2007).ABSTRACT Cultivated red rice (Oryza sativa L.) is the most important special type of rice in Brazil and makes an excellent food, mainly because of its nutritional value. Genetic variability, useful for rice breeding programs, exists among red rice accessions. The objectives of the present study were: (i) to determine the nature of gene action and magnitude of genetic components conditioning grain yield (GY), plant height (PH), and days to flowering (DTF); and (ii) to determine the combining ability for these traits in nine red rice lines (female parents) and four commercial cultivars (male parents). Thirteen parents, an F 2 generation of 18 crosses, and a check cultivar were evaluated at two locations (Goianira and Teresina, Brazil) using a randomized complete block design with four replications. Data (unbalanced because of lost plots) from this incomplete set of crosses in a factorial mating design were subjected to variance analyses using a general linear model. According to Baker's ratio, nonadditive genetic effects were more important than additive effects for the expression of the three traits. The dominance deviations were predominantly negative for GY and DTF and were positive for PH.
This work evaluated the efficiency of different genomic prediction (GP) methods in a diverse Mesoamerican panel of 339 common bean accessions, genotyped with 3398 SNP markers. Field experiments were carried out for three consecutive years, with adequate water supply (non‐stress—NS) and water restriction imposition (water‐stress—WS), analyzing seed weight (SW) and grain yield (GY). Two methods to predict the accuracies (rĝg) were adopted (GBLUP and Bayes) and also considered the environmental variation (GBLUP‐based reaction norm model). Similar accuracies were observed for both methods. For GY, the highest rĝg were detected under NS (rĝg = 0.49) in 2016 (rĝg = 0.49) and in the joint analysis for the WS condition (rĝg = 0.33), both for models using local landraces. For SW under NS, the rĝg was higher for the elite lines (rĝg = 0.72), whereas for WS, the rĝg dropped considerably, ranging from 0.45 to 0.61 for the joint analysis, considering the landraces and all samples, respectively. For GY and SW, under NS, the rĝg using both models increased with increasing number of SNPs, until reaching a plateau of 800 and 300 SNPs, respectively. Increasing the training population (TP) size resulted in greater accuracy. Taking in account the Genotype × Environment, the multienvironment model performed better especially for more complex traits (GY/NS: rĝg = 0.32). The GP approach has great potential to help commercial bean breeding programs improving the performance of target quantitative traits.
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