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Euphorbia heterophylla populations endued with resistance to both imazethapyr (an acetolactate synthase inhibitor) and fomesafen (a protoporphyrinogen oxidase inhibitor) were first detected in Brazil in 2004. The objectives of this study were to determine the number and dominance of genes conferring imazethapyr and fomesafen resistance in E. heterophylla and to establish the types of inheritance of the resistance traits. It was hypothesised that two dominant nuclear genes control this herbicide resistance and each gene confers resistance to a single herbicide. We crossed a susceptible (S) and a multiple‐resistant (R) E. heterophylla biotype and generated F₁ families which, in turn, were self‐fertilised to produce F₂ families. Backcrosses of the F₁ families with the S‐ and R parental biotypes resulted in BCₛ and BCᵣ families respectively. The F₁, F₂, BCₛ and BCᵣ families and the S and R parental biotypes were subjected to imazethapyr and fomesafen wherein each herbicide was used as a selecting agent. F₁ plants and the S‐ and R parental biotypes were used to evaluate the dominance of the resistance trait in multiple‐dose bioassays with imazethapyr and fomesafen. The observed frequencies of resistant plants in the F₁, F₂, BCₛ and BCᵣ families did not significantly differ from the expected frequencies for a resistance trait regulated by two dominant genes in which each gene confers resistance to a single herbicide. The lack of difference in herbicide response between the F₁ family and the R parental biotype was taken as evidence for completely dominant resistance to imazethapyr and fomesafen. Herbicide resistance in E. heterophylla presents with dominant monogenic nuclear inheritance for each herbicide mode of action. Our findings underscore the necessity and urgency of adopting integrated strategies to control E. heterophylla and to inhibit the evolution of new herbicide‐resistant strains.

Molecular markers are largely used to assist in crop improvement with the aim to achieve more favorable results in reduced time. In this study, we applied scientometric approaches to investigate and describe the application of molecular markers in genetic studies of common bean (Phaseolus vulgaris L.). A total of 671 articles, available on Thomson Reuters Web of Science database, published between 1991 and 2020, were analyzed, and it was determined that the USA and Brazil have the highest number of publications related to this subject. The main topics where molecular markers were used in common beans were fingerprinting, genetic diversity assessment, mapping, molecular marker development, marker-assisted selection, comparative genomics or evolution, and marker-trait association. They were also used to solve problems related to anthracnose (Colletotrichum lindemuthianum) and agronomic traits. As the genome sequence of common bean has been publicly available since 2014, SNP markers are frequently employed and their use is increasing, whereas other molecular markers are being bypassed.

In this study, we aim to develop and validate KASP molecular markers in soybean populations for Asian soybean rust (ASR) resistance gene Rpp1 (PI 200492, PI 594538A, PI 587880A), identify the gene hypothetically present in PI 594723, and validate KASP markers for Rpp2 (PI 230970), Rpp3 (PI 506764), Rpp4 (PI 459025A), and Rpp5 (PI 506764, PI 200487). Ten F2 soybean (Glycine max (L.) Merrill) populations derived from crosses between rust-susceptible (55I57RSF IPRO, 63I64RSF IPRO) x rust-resistant sources (PI 200492, PI 594738A, PI 587880A, PI 594723, PI 230970, PI 506764, PI 459025A and PI 200487) were evaluated. All F2 plants were individually evaluated in field conditions for ASR phenotypic reactions, classified according to sporulation level. SNP markers were developed according to markers associated with Rpp genes available at the SoyBase, using KASP methodology. Based on a slight difference in map position and different phenotypic disease reactions of PI 200492, the authors suggest that PI 594723 carries a resistance gene Rpp1-b. The Rpp1-b gene from PI 594723 was mapped in Chr 18 in a 12.4 cM region. The PIs carrying Rpp1-b (PI 594723, PI 587880A, and 594538A) showed strong resistance to ASR compared to the lines carrying Rpp1 (PI 200492). A total of 26 KASP markers were significantly associated (P Rpp1), M13 and M14 (Rpp2), M16, M17 and M20 (Rpp3), M25 and M26 (Rpp4), and M27 and M28 (Rpp5) have the potential to be used in marker-assisted selection strategies.

Genomic selection (GS) can potentially accelerate genetic improvement of soybean [Glycine max L. (Merrill)] by reducing the time to complete breeding cycles. The objectives of this study were to (1) explore the accuracy of GS in soybean, (2) evaluate the contribution of intrapopulational structure to the accuracy of GS, and (3) compare the efficiencies of phenotypic selection and GS in soybean. For this, phenotypic and genotypic data were collected from 324 soybean genotypes (243 recombinant inbred lines and 81 cultivars) and GS was performed for five yield related traits. BayesB methodology with a 10-fold cross-validation was used to compute accuracies. The GS accuracies were evaluated for grain yield, plant height, insertion of first pod, days to maturity, and 1000-grain weight at eight locations. We found that GS can reduce the time required to complete a selection cycle in soybean, which can lead to increased production of this commercially important crop. Furthermore, genotypic accuracy was similar regardless of population structure correction.

WRKY transcription factors (TFs) are responsible for the regulation of genes responsive to many plant growth and developmental cues, as well as to biotic and abiotic stresses. The modulation of gene expression by WRKY proteins primarily occurs by DNA binding at specific cis-regulatory elements, the W-box elements, which are short sequences located in the promoter region of certain genes. In addition, their action can occur through interaction with other TFs and the cellular transcription machinery. The current genome sequences available reveal a relatively large number of WRKY genes, reaching hundreds of copies. Recently, functional genomics studies in model plants have enabled the identification of function and mechanism of action of several WRKY TFs in plants. This review addresses the more recent studies in plants regarding the function of WRKY TFs in both model and crop plants for coping with environmental challenges, including a wide variety of abiotic and biotic stresses.

Drought stress on reproductive stages constitute a major problem for common bean (Phaseolus vulgaris L.) production because it affects flowering and pod-filling processes which are highly drought-sensitive. In this study, we used a greenhouse experiment to evaluate the response to drought stress in ten highly cultivated Brazilian genotypes in response to moderate intermittent drought during flowering and pod-filling periods (R7 and R8 stages). Morphological, biochemical, physiological and agronomic traits were used to identify tolerant cultivars and elucidate their strategies to cope this stress. The drought intensity index for the experiment reached 0.63. The cultivar IAC Imperador can be defined as a tolerant cultivar, presenting the lowest grain yield reduction (43%) and a reduced drought susceptibility index (0.65). This cultivar elevated their level of proline in roots under stress, which allowed the osmotic adjustment and the maintenance of an intermediate stomata closure during the day, which maintained the intrinsic WUE stable in NS and DS conditions. In addition, this cultivar was able to mobilize the assimilated carbon for the production of pods and grains, evidenced by the high harvest index and the high grain filling index. In this way, IAC Imperador can be used as a check in breeding programs to identify and select lineages with drought tolerance in common bean.

Iron (Fe) is an essential microelement for all living organisms playing important roles in several metabolic reactions. Rice (Oryza sativa L.) is commonly cultivated in paddy fields, where Fe goes through a reduction reaction from Fe3+ to Fe2+. Since Fe2+ is more soluble, it can reach toxic levels inside plant cells, constituting an important target for studies. Here we aimed to verify morphological changes of different rice genotypes focusing on deciphering the underlying molecular network induced upon Fe excess treatments with special emphasis on the role of four WRKY transcription factors. The transcriptional response peak of these WRKY transcription factors in rice seedlings occurs at 4 days of exposition to iron excess. OsWRKY55-like, OsWRKY46, OsWRKY64, and OsWRKY113 are up-regulated in BR IRGA 409, an iron-sensitive genotype, while in cultivars Nipponbare (moderately resistant) and EPAGRI 108 (resistant) the expression profiles of these transcription factors show similar behaviors. Here is also shown that some cis-regulatory elements known to be involved in other different stress responses can be linked to conditions of iron excess. Overall, here we support the role of WRKY transcription factors in iron stress tolerance with other important steps toward finding why some rice genotypes are more tolerant than others.

O melhoramento de plantas tem por base a ampliação da variabilidade genética existente através de cruzamentos artificiais planejados. Assim, é de fundamental importância o conhecimento das populações formadas, a fim de prever o potencial das combinações a partir de diferentes genitores, permitindo maior eficiência de seleção para o caráter desejado, otimizando o ganho genético. Dessa forma, o objetivo deste trabalho foi o de observar a variabilidade fenotípica dos caracteres estatura de planta, ciclo vegetativo e ciclo reprodutivo na geração F2 e prever as melhores combinações para a obtenção de constituições genéticas superiores. Para isso, cinco genótipos de aveia (UPF 16, UPF 18, UFRGS 7, UFRGS 17 e URPEL 15) foram cruzados de forma dialélica, sem a realização dos cruzamentos recíprocos, para o desenvolvimento das populações F2. Para analisar a variabilidade nas populações, foram utilizados os parâmetros: média, variância e assimetria da distribuição de freqüência. Os cruzamentos UPF 16 x UFRGS 17 e UFRGS 17 x URPEL 15 produziram grande quantidade de plantas de estatura reduzida. Para o caráter ciclo vegetativo, UPF 16 x UPF 18, UPF 16 x UFRGS 7, UPF 16 x UFRGS 17, UPF 16 x URPEL 15, UFRGS 7 x UFRGS 17 e UFRGS 7 x URPEL 15 foram os cruzamentos que produziram descendentes de ciclo curto. UPF 16 x UFRGS 17 e UPF 16 x URPEL 15 produziram amplo número de progênies de ciclo reprodutivo longo. Plant breeding is based on the pursue of an amplification of genetic variability through planned crosses. Thus, it is of fundamental importance to study the formed populations, in order to predict the potential of different parental combinations, allowing a higher selection efficiency for the desired trait, optimizing genetics gains. Thus, the objective of this work was to observe the phenotypic variability of the characters plant stature, vegetative cycle and reproductive cycle in F2 generation and to predict the best combinations to obtain superior genetic constitutions. Therefore, five oat genotypes (UPF 16, UPF 18, UFRGS 7, UFRGS 17 and URPEL 15) were crossed in a diallelic format, without reciprocal crosses, for the development of F2 populations. To analyze population variability, the following parameters were used: mean, variance and asymmetry of frequency distribution. The crosses UPF 16 x UFRGS 17 and UFRGS 17 x URPEL 15 produced a large amount of plants with shorter stature. For the character vegetative cycle, UPF 16 x UPF 18, UPF 16 x UFRGS 7, UPF 16 x UFRGS 17, UPF 16 x URPEL 15, UFRGS 7 x UFRGS 17 and UFRGS 7 x URPEL 15 were the crosses that produced short cycle plants. UPF 16 x UFRGS 17 and UPF 16 x URPEL 15 produced a large number of long-cycled progenies.

Reverse Transcription quantitative PCR (RT-qPCR) is one of the most important techniques for gene expression profiling due to its high sensibility and reproducibility. However, the reliability of the results is highly dependent on data normalization, performed by comparisons between the expression profiles of the genes of interest against those of constitutively expressed, reference genes. Although the technique is widely used in fruit postharvest experiments, the transcription stability of reference genes has not been thoroughly investigated under these experimental conditions. Thus, we have determined the transcriptional profile, under these conditions, of three genes commonly used as reference--ACTIN (MdACT), PROTEIN DISULPHIDE ISOMERASE (MdPDI) and UBIQUITIN-CONJUGATING ENZYME E2 (MdUBC)--along with two novel candidates--HISTONE 1 (MdH1) and NUCLEOSSOME ASSEMBLY 1 PROTEIN (MdNAP1). The expression profile of the genes was investigated throughout five experiments, with three of them encompassing the postharvest period and the other two, consisting of developmental and spatial phases. The transcriptional stability was comparatively investigated using four distinct software packages: BestKeeper, NormFinder, geNorm and DataAssist. Gene ranking results for transcriptional stability were similar for the investigated software packages, with the exception of BestKeeper. The classic reference gene MdUBC ranked among the most stably transcribed in all investigated experimental conditions. Transcript accumulation profiles for the novel reference candidate gene MdH1 were stable throughout the tested conditions, especially in experiments encompassing the postharvest period. Thus, our results present a novel reference gene for postharvest experiments in apple and reinforce the importance of checking the transcription profile of reference genes under the experimental conditions of interest.