Enzymatic activity and gene expression related to drought stress tolerance in maize seeds and seedlings

Drought stress is a major limiting factor for the development of maize, and the identification of the expression of genes related to this stress in seeds and seedlings can be an important tool to accelerate the selection process. The expression of genes related to tolerance to water deficit in seeds and in different tissues of maize seedlings were evaluated. Four tolerant genotypes (91-T, 32-T, 91x75-T, 32x75-T) and four non-tolerant genotypes (37-NT, 57-NT, 37x57-NT and 31x37-NT) were seeded in a substrate with 10% (stress) and 70% (control) water retention capacity. The expression of 4 enzymes were evaluated: catalase (CAT), peroxidase (PO), esterase (EST), and heat-resistant protein (HRP), as well as the relative expression of 6 genes: ZmLEA3, ZmPP2C, ZmCPK11, ZmDREB2A/2.1s, ZmDBP3 and ZmAN13 were evaluated in seed, shoots and roots of seedlings submitted or not to stress. There was variation in the expression of CAT, PO, SOD, EST and HRP enzymes among the evaluated genotypes and also in the different tissues evaluated. Higher expression of the CAT and PO was observed in the shoots. There was a greater expression of the EST in the genotypes non-tolerant to water deficit. HRP was expressed only in seeds. In the aerial part of maize seedlings, classified as tolerant, higher expression of genes ZmLEA3 and ZmCPK11 was observed. There was a higher expression of the ZmAN13 and ZmDREB2A/2.1S genes in roots developed under stress conditions and a higher expression of the ZmPP2C gene in seeds of line 91-T, which is classified as tolerant to drought stress.

Identicafição de cultivares e certificação da pureza genética de gladíolo por meio de marcadores morfológicos / Identification of cultivars and certification of genetic purity of gladiolus through morphologic markers

A caracterização de cultivares de flores é fundamental nos processos de registro e proteção dessas e também na certificação da pureza genética. Nesse trabalho foram realizadas a caracterização e a certificação da pureza genética de cultivares de Gladiolus sp. por meio de marcadores morfológicos. Utilizaram-se onze cultivares de Gladiolus sp., e para a caracterização das cultivares, as parcelas foram constituídas de 25 plantas avaliando-se características dos cormos, folhas e flores. O delineamento experimental adotado foi de blocos casualizados, com quatro repetições Para a certificação da pureza genética, foram instaladas parcelas constituídas de 24 plantas e cormos contendo contaminação varietal em diferentes proporções. Foram utilizadas três cultivares para compor os tratamentos e as avaliações foram conduzidas por três avaliadores que desconheciam a porcentagem existente de contaminação varietal. Foram calculadas as porcentagens de acerto e de erro com base nos resultados obtidos nas avaliações. Foi calculado o desvio padrão da média dos resultados nas quatro repetições, obtidos pelos três avaliadores. Para verificar a significância dos desvios entre os resultados obtidos pelos avaliadores foi utilizado o teste de qui-quadrado ( χ²). Por meio de características do cormo é possível diferenciar quatro cultivares das onze avaliadas. A característica da cor das flores é o descritor morfológico mais seguro para a diferenciação das cultivares de gladíolo. Dependendo das características das cultivares contaminantes e das cultivares em análises é possível utilizar descritores morfológicos para a certificação de pureza genética em cultivares de gladíolo.

The characterization of flower cultivars is fundamental in the registration and protection processes and also in the genetic purity certification. In this work, both the characterization and the genetic purity certification of cultivars of Gladiolus sp by means of morphologic markers were made. Eleven cultivars of Gladiolus sp. were used and for the characterization of the cultivars, the plots were made up of 25 plants, evaluating the characteristics of corms, leaves and flowers. The used experimental design was the one of randomized blocks with four replicates. For the genetic purity certification, plots with 24 plants and corms containing varietal contaminations in different proportions were established. Three cultivars were used to make up the treatments, and the evaluations were conducted by three evaluators who were unaware of the existent percentage of varietal contamination. The percentage of mistakes was calculated based upon the obtained results of the evaluations. The standard deviation of the means of the results in the four replicates obtained by the three evaluators was calculated. In order to verify the significance of the deviations among the obtained results by the evaluators, Chi-square test ( χ2) was used. By means of corm characteristics, it is possible to distinguish four cultivars out of the eleven evaluated. The characteristic of flower color is the safest morphological descriptor for distinguishing gladiolus cultivars. Depending on the characteristics of the contaminant cultivars and on the ones under analyses, it is possible to use morphological descriptors for the genetic purity certification in gladiolus cultivars.