Inheritance of Resistance to Bacterial Halo Blight and Bacterial Leaf Spot in Arabica Coffee.

Developing coffee cultivars resistant to multiple diseases by combining resistance genes is a top priority in breeding programs. To create cultivars resistant to diseases and nematodes, we transferred genes for resistance to bacterial infections caused by Pseudomonas coronafaciens pv. garcae, which causes bacterial halo blight (BHB), and P. amygdali pv. tabaci, which causes bacterial leaf spots (BLS), into Arabica coffee. Genetic analyses were conducted on breeding populations to estimate the number and function of genes that confer resistance to BHB and BLS. In total, 2,109 plants in the F2 generation and reciprocal backcrosses were inoculated with P. coronafaciens pv. garcae, while 1,996 plants were inoculated with P. amygdali pv. tabaci. Results showed that resistance to both pathogens had a heritability of 0.99, and the segregations of resistance indicated that each disease was controlled by a single dominant gene. The analyses also revealed that the resistance genes for BHB and BLS were linked, with an average distance of 10.75 cM between them on the same chromosome.

Elevated Temperatures Impose Transcriptional Constraints and Elicit Intraspecific Differences Between Coffee Genotypes.

The projected impact of global warming on coffee production may require the heat-adapted genotypes in the next decades. To identify cellular strategies in response to warmer temperatures, we compared the effect of elevated temperature on two commercial Coffea arabica L. genotypes exploring leaf physiology, transcriptome, and carbohydrate/protein composition. Growth temperatures were 23/19°C (day/night), as optimal condition (OpT), and 30/26°C (day/night) as a possible warmer scenario (WaT). The cv. Acauã showed lower levels of leaf temperature (Tleaf) under both conditions compared to cv. Catuaí, whereas slightly or no differences for other leaf physiological parameters. Therefore, to explore temperature responsive pathways the leaf transcriptome was examined using RNAseq. Genotypes showed a marked number of differentially-expressed genes (DEGs) under OpT, however DEGs strongly decrease in both at WaT condition indicating a transcriptional constraint. DEGs responsive to WaT revealed shared and genotype-specific genes mostly related to carbohydrate metabolism. Under OpT, leaf starch content was greater in cv. Acauã and, as WaT temperature was imposed, the leaf soluble sugar did not change in contrast to cv. Catuaí, although the levels of leaf starch, sucrose, and leaf protein decreased in both genotypes. These findings revealed intraspecific differences in the underlying transcriptional and metabolic interconnected pathways responsive to warmer temperatures, which is potentially linked to thermotolerance, and thus may be useful as biomarkers in breeding for a changing climate.

Comportamento de progênies F4 obtidas por cruzamentos de 'Icatu' com 'Catimor' / Behavior of F4 progenies obtained from crossing of Icatu with Catimor

Conduziu-se este trabalho com o objetivo de avaliar progênies de cafeeiro resultantes do cruzamento entre 'Icatu' x 'Catimor', quanto à produtividade e vigor vegetativo e selecionar progênies superiores para avançar no programa de melhoramento dessa população. O delineamento utilizado foi em blocos casualizados com quatro repetições, 30 tratamentos (29 progênies do cruzamento mais a cultivar Rubi MG 1192, utilizada como testemunha). Para análise de variância dos dados adotou-se o esquema de parcela subdividida no tempo. Foram analisados a produção em sacas beneficiadas.ha-1 de seis colheitas 2001/2002 a 2006/2007 e o vigor vegetativo avaliado após a colheita 2006/2007. Os resultados obtidos permitem verificar a presença da variabilidade genética para produção entre as progênies avaliadas, fato confirmado pela alta estimativa da maioria das progênies estudadas, demonstraram que é possível selecionar progênies superiores na população estudada.

The objective of this research was to evaluate coffee progenies resulted from the crossing of 'Icatu' with 'Catimor' in relation to their production and plant vigor and to select higher quality progenies to advance the breeding program of this population. For this purpose, a randomized complete block design was carried out with four replications and for the analysis of variance, the Split plot temporal arrangement was adopted. Twenty nine progenies plus the Rubi MG 1192 cultivar, used as a control, were evaluated. The yield of beans in bags.ha-1 of six harvests from 2001/2002 to 2006/2007 was evaluated and the plant vigor after the harvest was assessed. The results indicated that the evaluated progenies showed variability mainly for grain yield confirmed by heritability. This condition associated to high bean yields, which reached 62.0 bags.ha-1 and high plant vigor, showed the possibility of selecting outstanding progenies in the studied population.

Resistência parcial à necrose dos frutos em genótipos de café arábica / Partial resistance to fruit necrosis in arabic coffee genotypes

Neste trabalho, objetivou-se identificar em genótipos de café arábica (Coffea arabica L.) fontes de resistência à necrose de frutos em condições de campo. As variáveis resistência à necrose de frutos ("NF"), quantidade média de frutos por nó produtivo ("FN") e índice de luminosidade dentro da copa da planta ("LUM") foram avaliadas em ensaio de campo no IAPAR (Londrina), em dezembro de 2004, em cafeeiros com três anos de idade. Foi avaliada a variável "NF", atribuindo notas de 1 a 5 sendo 1 para plantas com 0 por cento a 5 por cento de frutos necrosados. "FN" foi avaliada seguindo uma escala de notas de 1 a 5, onde 1 representa plantas com 0 a 3 frutos/ nó e nota 5 com mais do que 15 frutos/ nó. A avaliação da variável "LUM" foi visual e seguiu as notas de 1 a 5, onde 1 representa plantas com pouca luminosidade dentro da copa da planta. Dos 19 genótipos avaliados, 2 apresentaram moderada resistência, 7 moderada suscetibilidade, 5 suscetíveis e 5 altamente suscetíveis. As cultivares Obatã IAC 1669-20 e Catucaí Vermelho 4-79 apresentaram o melhor nível de resistência parcial de campo, ou seja, com moderada resistência à necrose de frutos associada ao Colletotrichum spp.

The aim of this research was to identify in Coffea arabica L. coffee genotypes resistance sources to fruit necrosis in field conditions. The variables fruit necrosis ("NF"), fruits per productive nodes average ("FN") and luminosity index inside of the plant canopy ("LUM") were evaluated in field assay at IAPAR (Londrina), in December 2004 on three years old coffee trees. The "NF" variable were evaluated attributing scores from 1 to 5, where score 1 represented plants with 0 to 5 percent of necrosed fruits. "FN" were evaluated following a score scale from 1 to 5, where score 1 represented plants with 0 to 3 fruits/ node and score 5 with more than 15 fruits/ node. The evaluation of the variable "LUM" was visual and followed the scores from 1 to 5, where score 1 represented plants with low luminosity inside the canopy. Out of the 19 evaluated coffee genotypes, 2 presented moderate resistance, 7 moderate susceptibility, 5 susceptibility and 5 high susceptibility. The cultivars Obatã IAC 1669-20 and Catucaí Vermelho 4-79 presented the best level of partial field resistance, or either, with moderate resistance to fruit necrosis associated to Colletotrichum spp.

Correlação entre a necrose de frutos associada ao Colletotrichum spp. com as características frutos por nó e produtividade entre genótipos de café arábica / Correlation between fruit necrosis associated to Colletotrichum spp. with the fruits per node and yield traits of arabic coffee

O fungo Colletotrichum spp. vem sendo associado à graves perdas para a cafeicultura brasileira. Objetivou-se neste trabalho verificar a existência de relação entre a variável necrose de frutos associada ao Colletotrichum spp. ("COL") com a quantidade média de frutos por nó produtivo ("FN") e com a produção ("PRD") em genótipos de café arábica. O ensaio de campo foi realizado no IAPAR (Londrina, PR, Brasil) em dezembro de 2004 e em cafeeiros com três anos de idade. A variável "COL" foi avaliada atribuindo-se notas de 1 a 5, onde 1 representam plantas com 0 por cento a 5 por cento de frutos necrosados. "FN" foi avaliada seguindo uma escala de notas de 1 a 5, onde 1 representa plantas com 0 a 3 frutos/ nó e nota 5 com mais do que 15 frutos/ nó. A avaliação visual subjetiva da produção foi estimada em litros de frutos em estádio cereja, por planta. A correlação de Pearson foi estimada para avaliar a existência de associações entre as variáveis. Foram observadas correlações positivas e significativas a 1 por cento entre "COL" e "FN" e entre "COL" e "PRD". A necrose de frutos foi mais intensa em cafeeiros com mais produção e com mais frutos por nó produtivo. Sugere-se que a avaliação da resistência de campo à necrose dos frutos associada à presença de Colletotrichum spp. seja realizada em cafeeiros com alta produção e com alta quantidade de frutos por nó produtivo.

Different fungi species of genus Colletotrichum has been associated with losses to the Brazilian coffee crop. The aim of this research was to evaluate the association between the variable fruit necrosis associated to Colletotrichum spp. ("COL") with the fruits per productive node average ("FN") and between "COL" and the yield ("PRD") in Coffea arabica L. genotypes. The field assay was evaluated at IAPAR (Londrina, PR, Brazil), in December 2004 and on coffee trees with three years old. The "COL" variable was evaluated attributing scores from 1 to 5, where score 1 represents plants with 0 percent to 5 percent of necrosed fruits. "FN" was evaluated following a score scale from 1 to 5, where score 1 represents plants with 0 to 3 fruits/ node and score 5 with more than 15 fruits/ node. The yield per plant was estimated by visual evaluation in liters of cherry fruits per plant. The Pearson's coefficient of correlation was estimated to evaluate the associations between variables. Positive and significant correlations were observed at 1 percent between "COL" x "FN" and between "COL" x "PRD". The fruit necrosis was higher on coffees with higher yield and higher number of fruits per productive node. It is suggested that the field evaluation for resistance to fruit necrosis would be better if accomplished on coffee trees with high yield and high number of fruits per productive node.

Caffeine inheritance in interspecific hybrids of Coffea arabica x Coffea canephora (Gentianales, Rubiaceae)

Caffeine inheritance was investigated in F2 and BC1F1 generations between Coffea arabica var. Bourbon Vermelho (BV) and Coffea canephora var. Robusta 4x (R4x). The caffeine content of seeds and leaves was determined during 2004 and 2005. Microsatellite loci-markers were used to deduce the meiotic pattern of chromosome pairing of tetraploid interspecific hybrids. Genetic analysis indicated that caffeine content in seeds was quantitatively inherited and controlled by genes with additive effects. The estimates of broad-sense heritability of caffeine content in seeds were high for both generations. In coffee leaves, the caffeine content (BSH) from the same populations showed transgressive segregants with enhanced levels and high BSH. Segregation of loci-markers in BC1F1 populations showed that the ratios of the gametes genotype did not differ significantly from those expected assuming random associations and tetrasomic inheritance. The results confirm the existence of distinct mechanisms controlling the caffeine content in seeds and leaves, the gene exchange between the C. arabica BV and C. canephora R4x genomes and favorable conditions for improving caffeine content in this coffee population.

Partial resistance to fruit necrosis associated to Colletotrichum spp. among arabic coffee genotypes

The aim of this study was to evaluate the resistance to fruit necrosis associated to Colletotrichum spp. in Coffea arabica L.. Twenty-two arabic coffee genotypes were performed in a randomized block design, with three replications and ten plants per plot. They were evaluated for the variables fruit necrosis, luminosity index inside of the plant canopy and fruits per productive nodes of the plants. There was genetic variability for the resistance to fruit necrosis. Different partial resistance levels, varying from highly susceptible (score = 3.89) to moderately resistant (score = 1.77) were observed. The genotypes that presented moderate resistance were the cultivars IPR-100, IPR-103, IPR-105 and IPR-108 and the coffee selection IAPAR-00023.

Diferentes espécies de fungo do gênero têm sido associadas a perdas na cafeicultura brasileira. O objetivo deste trabalho foi avaliar a resistência à necrose de frutos associada ao Colletotrichum spp. em Coffea arabica L.. Vinte e dois genótipos de café foram avaliados no delineamento em blocos ao acaso com três repetições e dez plantas por parcela. As avaliações foram realizadas no IAPAR, Londrina, em janeiro de 2004 para as variáveis necrose de frutos, índice de luminosidade dentro da copa da planta e frutos por nó produtivo. Existe variabilidade genética em cafeeiros arábicos para a resistência à necrose de frutos. Foi observado diferentes níveis de resistência parcial, variando de altamente suscetível (nota = 3,89) a moderadamente resistente (nota = 1,77). Os genótipos que apresentaram moderada resistência foram as cultivares IPR-100, IPR-103, IPR-105 e IPR-108 e a seleção de café IAPAR-00023.