Resumo -O objetivo deste trabalho foi avaliar alguns aspectos da biologia floral e do sistema reprodutivo de Jatropha curcas, em Janaúba, MG. Foram registrados: o número de flores femininas e masculinas; o intervalo de abertura das flores femininas; e a formação de frutos por apomixia, autofecundação, geitonogamia e xenogamia. A proporção de flores masculinas para femininas foi de 20:1. O intervalo de abertura das flores femininas variou de um a sete dias, conforme o número delas na inflorescência. No teste de apomixia, houve formação de frutos em apenas 5% das flores avaliadas. A percentagem de frutificação variou de 79 a 88% na autofecundação manual, na geitonogamia e na xenogamia. Na autofecundação sem a polinização manual a frutificação foi de 20%, e os frutos formados foram significativamente menores, com número inferior de sementes por fruto e menor índice de velocidade de emergência. As sementes foram semelhantes às formadas por polinização natural. É possível a realização de cruzamentos controlados em pinhão-manso, e não há autoincompatibilidade nesta espécie.Termos para indexação: Jatropha curcas, autofecundação, geitonogamia, polinização natural, xenogamia. Floral biology and artificial polinization in physic nut in the north of Minas Gerais state, BrazilAbstract -The aim of this work was to evaluate some aspects of the floral biology and of the reproductive system of Jatropha curcas, in Janaúba county, MG, Brazil. The number of female and male flowers, the interval between the opening of female flowers, and the formation of fruits by apomixis, self-pollination, geitonogamy and by xenogamy were registered. The ratio of male to female flowers was 20:1. The interval of opening of female flowers was of one to seven days, depending on the number of female flowers in the inflorescence. On the apomixy test, the formation of fruits occurred in only 5% of the evaluated flowers. The fruit set was between 79 and 88% through the manual self-pollination, and through the geitonogamy, and the xenogamy. In the self-pollination treatment, without the hand-pollination, the fruit set was of 20%, and the fruits formed were significantly smaller, with a lesser number of seeds per fruit and lower rate of emergence. The seeds were similar to the ones formed by natural pollination. Artificial cross-pollination is possible on physic nuts, and there is no self-incompatibility within this species.Index terms: Jatropha curcas, self-pollination, geitonogamy, natural pollination, xenogamy. IntroduçãoOs procedimentos adotados na execução dos trabalhos de melhoramento genético de espécies perenes frutíferas arbóreas dependem, fundamentalmente, do seu modo de reprodução, do conhecimento da biologia floral, inclusive a morfologia floral, do tipo de reprodução e dos aspectos relativos à polinização e à fertilização. São importantes, também, as consequências das alterações induzidas artificialmente no modo de reprodução, nos cruzamentos dirigidos e nas autofecundações. Além disso, o fruto e as sementes são economicamente as partes mais ...

Resumo -O objetivo deste trabalho foi avaliar a base genética da resistência de Lycopersicon hirsutum ao potyvírus Pepper yellow mosaic virus (PepYMV). Foram avaliadas 540 plantas, inclusive os parentais 'Santa Clara' (suscetível) e 'BGH 6902' (resistente), e as gerações F 1 , F 2 , RC 1:1 e RC 1:2 , derivadas do cruzamento desses parentais. As plantas receberam inoculações mecanicamente, e a concentração viral de PepYMV em cada planta foi determinada por ELISA indireto. Foram realizadas as análises quantitativa e qualitativa. A primeira, baseada na concentração viral de cada planta, indicou herança oligogênica com herdabilidade de 99%. Os mesmos dados, quando analisados de forma qualitativa, indicaram herança governada por dois genes, com interação epistática dominante e recessiva. Entretanto, quando foi analisada a geração F 2:3 , oriunda da autofecundação de plantas F 2 resistentes, a hipótese de dois genes foi descartada e a de um gene, com dominância completa entre os alelos, foi a que melhor se ajustou aos dados. A análise qualitativa, pela sintomatologia observada, demonstrou que a herança da resistência ao PepYMV é determinada por um gene recessivo, com ausência de dominância entre os seus alelos.Termos para indexação: Lycopersicon hirsutum, Pepper yellow mosaic virus, herança da resistência, resistência recessiva. Resistance genetic basis of a wild tomato access to pepper yellow mosaic virusAbstract -The aim of this work was to evaluate the genetic basis of resistance of Lycopersicon hirsutum to the potyvirus Pepper yellow mosaic virus (PepYMV). Five hundred and forty plants, including the parentals 'Santa Clara' (susceptible) and 'BGH 6902' (resistant) were evaluated, as well as the generations F 1 , F 2 , RC 1:1 and RC 1:2 , from the crossing of the above parentals. PepYMV was mechanically inoculated, and the virus concentration in each plant was determined by indirect ELISA. The quantitative and qualitative analyses were carried out. The first one, based on the virus concentration of each plant, suggest oligogenic inheritance with heritability of 99%. The same data, when analyzed under the qualitative form, indicated an inheritance governed by two genes, with dominant and recessive epistatic interaction. However, when F 2:3 generation, arising from self-fertilization of resistant F 2 plants, was analyzed, the hypothesis of two genes was rejected, while the best fitted to data was that of one gene with complete dominance among the alleles. The qualitative analysis, considering sintomatology observed, showed that the inheritance of resistance to PepYMV is determined by a recessive gene, with the absence of dominance among their alleles.

Resumo-O presente estudo objetivou estimar parâmetros genéticos da fase vegetativa em cinco populações de pinhão manso (Jatropha curcas L.). As progênies de meios-irmãos foram plantadas na Fazenda da Biojan, em Janaúba, MG. Aos três e seis meses de idade, foram avaliadas as características altura de plantas, diâmetro de caule, número de ramos e projeção da copa, em todas as plantas. A população 2 não apresentou variabilidade genética para os caracteres avaliados. Nas demais populações, com a seleção dos dez melhores indivíduos, os ganhos genéticos preditos variaram de 4% a 8% para altura de plantas (populações 1 e 4), 5% a 7% para diâmetro de caule (populações 1 e 5), 14% e 25% para número de ramos aos 3 meses (populações 3 e 5) e 9% para projeção da copa na população 4. De acordo com os resultados observados neste trabalho, estas populações são adequadas para dar continuidade ao programa de melhoramento genético da espécie na região. Termos para indexação: Variabilidade, herdabilidade, acurácia, ganho genético. Genetic evaluation and genetic gains with the selection for Jatropha curcas populations Abstract-This work aimed at estimating genetic parameters from the vegetative stage in five populations from Jatropha curcas L. The half sib progenies were cultivated at Biojan farm, in Janaúba, MG. Plant height, stem diameter, number of branches and crown projection were assessed in all plants at three and six months old. In population 2, there was no genetic variability for all traits evaluated. The genetic gains estimated with the selection from the ten best individuals in other populations were 4% to 8% for plant height (population 1 and 4), 5% to 7% for stem diameter (population 1 and 5), 14% to 25% for the number or branches (population 3 and 5) and 9% for crown projections in population 4. According to the results obtained from this study, these populations are adequate for the continuity of the breeding program of this species in the region.

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In this study, we investigated resistance traits to the sugarcane borer Diatraea saccharalis Fab. (Lepidoptera: Crambidae) in the leaves and stalks of six sugarcane cultivars in a series of greenhouse and laboratory assays. Investigation of plant factors and infestation rates to better discriminate stalk damage by the sugarcane borer indicated that infestation of 7-month-old, single plants with 20 larvae at the third or fourth instar per plant was suitable to assess tunneling length. Three cultivars (i.e. SP803280, RB928064, and RB835486) had lower stalk damage (i.e. tunnel length) than cultivar SP891115, which exhibited relatively greater susceptibility to tunneling by the borer. The time required for the larvae to enter the sugarcane stalk was longer for cultivar SP803280, indicating resistance traits on the stalk surface, which correlated with lower stalk damage. Larvae feeding on SP813250 stalks had the lowest weight gain, indicating that this cultivar has resistance traits to larval development within its stalks. Cultivars RB867515 and SP891115 resulted in the highest mortality of early-stage larvae feeding on leaves, indicating the presence of resistance factors in their leaves. Multi-trait cluster and principal component analyses placed the cultivars into three and four clusters, respectively. The cultivars placed in different groups that exhibited resistance to leaf feeding, stalk entrance, and tunneling by the sugarcane borer could be used for crossings in sugarcane breeding programs with the goal of obtaining higher levels of resistance to D. saccharalis.

The tomato is a crop of great economical importance, however it is susceptible to a large number of pests and diseases, including viral disease for which the best control strategy is genetic resistance. The disease, caused by Pepper yellow mosaic virus (PepYMV) has become a recent problem. Consequently, the idea of this work was to screen 376 accessions of Lycopersicon sp. to find possible sources of resistance to PepYMV. Out of 355 accessions of L. esculentum inoculated with PepYMV, 52 did not express symptoms. However, the virus reached high concentration in the tissues as measured by indirect ELISA, and therefore they were not considered as safe sources of resistance. Among 21 accessions of wild Lycopersicon species, one of L. hirsutum was shown to be resistant, with no observed symptoms. A low concentration of the virus was detected as measured by indirect ELISA. This accession seems to be suitable for breeding programs aiming at incorporating resistance for this disease into commercial tomato cultivars.

ABSTRACT. Superior inbred clones selected in S 1 families can integrate an individual reciprocal recurrent selection program in sugarcane by eliminating the genetic load of the population and exploring superior hybrid combinations. Molecular markers can be used for reliable identification of the true selfing-derived clones in these S 1 populations. The objective of this study was to confirm true self-fertilized individuals in sugarcane families using microsatellite markers aimed at the use of self-fertilized plants in an individual reciprocal recurrent selection strategy. Self-fertilized individuals Selfing confirmation and recurrent selection in sugarcane using SSR from five cultivars were genotyped with eight simple sequence repeat (SSR) markers. The markers generated 62 polymorphic markers, with an average of seven polymorphic alleles across the cultivars tested. Three loci revealed highly informative bands and were used to assess the level of selfing in five S 1 families. Selfing in these families ranged from 71.7 to 97.6%. The SSR loci provide a reliable and accurate method to identify S 1 progenies in sugarcane crosses and can be used as a tool to assist selection strategies in sugarcane breeding programs.

Resumo-O presente estudo objetivou estimar parâmetros genéticos da fase vegetativa em cinco populações de pinhão manso (Jatropha curcas L.). As progênies de meios-irmãos foram plantadas na Fazenda da Biojan, em Janaúba, MG. Aos três e seis meses de idade, foram avaliadas as características altura de plantas, diâmetro de caule, número de ramos e projeção da copa, em todas as plantas. A população 2 não apresentou variabilidade genética para os caracteres avaliados. Nas demais populações, com a seleção dos dez melhores indivíduos, os ganhos genéticos preditos variaram de 4% a 8% para altura de plantas (populações 1 e 4), 5% a 7% para diâmetro de caule (populações 1 e 5), 14% e 25% para número de ramos aos 3 meses (populações 3 e 5) e 9% para projeção da copa na população 4. De acordo com os resultados observados neste trabalho, estas populações são adequadas para dar continuidade ao programa de melhoramento genético da espécie na região. Termos para indexação: Variabilidade, herdabilidade, acurácia, ganho genético. Genetic evaluation and genetic gains with the selection for Jatropha curcas populations Abstract-This work aimed at estimating genetic parameters from the vegetative stage in five populations from Jatropha curcas L. The half sib progenies were cultivated at Biojan farm, in Janaúba, MG. Plant height, stem diameter, number of branches and crown projection were assessed in all plants at three and six months old. In population 2, there was no genetic variability for all traits evaluated. The genetic gains estimated with the selection from the ten best individuals in other populations were 4% to 8% for plant height (population 1 and 4), 5% to 7% for stem diameter (population 1 and 5), 14% to 25% for the number or branches (population 3 and 5) and 9% for crown projections in population 4. According to the results obtained from this study, these populations are adequate for the continuity of the breeding program of this species in the region.