Identificação de linhagens avançadas de alface quanto à resistência a Meloidogyne javanica

Abstract

RESUMOObjetivou-se, no presente trabalho, avaliar o comportamento de linhagens de alface quanto à resistência ao nematoide das galhas Meloidogyne javanica, identificando a provável existência de linhagens homozigotas para o caráter. Foram utilizados como tratamentos cinco linhagens F 4 e seis linhagens F 5 , juntamente com as testemunhas 'Grand Rapids' (resistente) e 'Regina 71' (suscetível), além da cultivar de tomateiro Santa Clara. A semeadura foi feita em bandejas de poliestireno expandido, sendo o substrato infestado com ovos de M. javanica, na proporção de 30 ovos cm -3 de substrato. Aos quarenta e sete dias após a infestação, cada planta foi avaliada individualmente quanto aos seguintes caracteres: índice visual de galhas, número de ovos, fator de reprodução e índice de reprodução. Cada linhagem foi comparada com as testemunhas 'Regina 71' e 'Grand Rapids', para cada característica, através do teste de Dunnett (5%), obtendo-se a significância em relação a cada uma das testemunhas, permitindo a classificação de cada linhagem como homozigota resistente, homozigota suscetível ou segregante. Pelos resultados obtidos conclui-se que seis linhagens (AFX 018C 002 23 15, AFX 018C 002 23 22, AFX 018C 005 42 20, AFX 018C 005 44 22, AFX 018C 005 44 28 e AFX 022B 010 31) foram consideradas homozigotas resistentes para as características avaliadas, podendo ser utilizadas como novas fontes de resistência ao M. javanica em programas de melhoramento de alface. Termos para indexação:Lactuca sativa L., melhoramento, seleção. ABSTRACTThe objective of the present work was to evaluate the behavior of lettuce lineages as for resistence to nematode from the Meloidogyne javanica root-knots, identifying probable existence of homozigote lineages for the characteristics. Five F 4 and six F 5 lineages were used as treatments together with the controls 'Grand Rapids' (resistent) and 'Regina 71' (susceptible), apart from the Santa Clara tomato plant cultivar. The sowing was done over expanded polystyrene trays with the substrate infested by M. javanica eggs in the proportion of 30 eggs cm -3 of substrat. At 47 days after infestation, each plant was evaluated individually as for the following characteristics: visual level of root-knots, number of eggs, level and factor of reproduction. Every lineage was compared to the 'Regina 71' and 'Grand Rapids' for each characteristic, through Dunnett (5%) test, obtaining the significance in relation to each control, allowing the classification of each lineage as resistant homozigote, susceptible homozigote or segregated. The results obtained showed that six lineages (AFX 018C 002 23 15, AFX 018C 002 23 22, AFX 018C 005 42 20, AFX 018C 005 44 22, AFX 018C 005 44 28 and AFX 022B 010 31) were considered resistant homozigote for the evaluated characteristics, and maybe being used as new sources of resistance to M. javanica in lettuce breeding program.

Meloidogyne incognita resistant strains of leaf lettuce

“…In addition, the same behavior for resistance was found by Gomes et al (2000) in a mixture of progenies from these families when tested in F 4 and F 5 for resistance to M incognita spp.. Finally, Ferreira et al (2011) evaluated these progenies for M. javanica resistance and found six resistant progenies, suggesting that maybe the control is found on the same locus. In this work, 13 progenies were found to be resistant for all the evaluated M. incognita spp.…”

“…Furthermore, the progenies AFX-020C-06-13-02, AFX-020C-06-20-03, AFX-020C-06-20-02, and AFX-020C-06-20-04 originated from families considered segregating for M. javanica (Ferreira et al, 2011). In addition, the same behavior for resistance was found by Gomes et al (2000) in a mixture of progenies from these families when tested in F 4 and F 5 for resistance to M incognita spp..…”

“…The third experiment was conducted in the Greenhouse and Nematology Laboratory of the Plant Pathology Department, Federal Rural University of Pernambuco, Recife, Pernambuco, Brazil (8° 04' 03" S, 34° 55' 00" W; 4 m average altitude; 19°C average temperature) from March to April, 2013. In experiment 1, five F3:4 strains, five F3:5 strains, two commercial cultivars -Elisa and Regiane, and two advanced lines of thesestrains 41 and 62, were evaluated (Souza et al, 2008). The F3:4 strains used in Experiment 1 were obtained according to the Oliveira et al 4661 genealogy described by Ferreira et al (2011). The F3:4 offspring were self-fertilized, and the F3:5 progeny were also used in this experiment.…”

“…In another study involving 'Regina-71' and 'Salinas-88' (resistant parent), 12 F 4 progenies homozygous for resistance were selected (Carvalho Filho et al, 2007). When comparing 11 advanced lines of lettuce [("Regina-71" × "Grand Rapids") × "Elisa"], six lines were found to be homozygously resistant to M. javanica (Ferreira et al, 2011). These results demonstrate the possibility for selection of resistant homozygous families from crossing contrasting parents.…”

“…Ferreira et al (2011), working with advanced lines originating from a cross between Grand rapids and Regina-71, achieved lines resistant to root-knot nematode.…”