Assessing Psidium guajava × P. guineense hybrids tolerance to Meloidogyne enterolobii
2012
Costa, S.R da | Santos, C.A.F. | Castro, J.M.C.
Commercial guava orchards have been destroyed in the São Francisco river Valley, northeastern Brazil, by the Meloidogyne enterolobii nematode but to date no effective control has been identified. The objective of the present study was to obtain and assess interspecific hybrids between Psidium guajava × P. guineense for tolerance to M. enterolobii, for use as guava rootstock or in genetic studies. Crossings were made between P. guajava GUA 161 PE accession and the P. guineense ARA 138 RR and ARA 153 BA accessions. The crossings were made when the calyx ruptured on the flower buds, and two SSR microsatellite markers were used to confirm the hybridization. When the plants reached 15 to 20 cm in height, they were inoculated with a suspension containing 10,000 nematode eggs. Four months after inoculation, the soil was removed from the plants and individual evaluation was carried out for the number of galls, number of eggs and reproductive factor (RF). The plants in the two crossings were considered as hybrids when genotyped with the mPgCI 251 and mPgCI 252 loci. The 10 plants from the 161 PE × ARA 138 RR cross assessed were tolerant to the nematode, with gall index and RF equal to zero. Seven of the 10 plants of the GUA 161 PE × ARA 153 BA cross assessed were considered susceptible to the nematode. The results suggested variability for tolerance among P. guineense accessions and that tolerance to the nematode could be conferred by a dominant allele. Plants of the interspecific hybrid grew similarly to the guava trees at eight months of age in field and were highly compatible with ‘Paluma’ guava, indicating that this strategy can present excellent results in controlling M. enterolobii.
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