Simultaneous cloning and selection of Psidium genotypes resistant to Meloidogyne enterolobii

One of the obstacles to arboreal plant breeding is the time required between the selection of superior genotypes and their multiplication. This study investigates Psidium (guava) hybrids developed to obtain rootstock or new scions resistant to the nematode Meloidogyne enterolobii. The use of half-siblings or hybrid seeds of these genetic materials does not preserve the genetic profile of resistant individuals, making destructive selection methods unfeasible. Propagating juvenile Psidium material by minicutting produces a high rooting percentage, facilitating the cloning of segregating families and reducing the time required to produce replicas. In this study, segregating families for resistance to M. enterolobii were cloned by minicutting, with replicas maintained in clonal minigardens while the mother plants were inoculated and evaluated for nematode reproduction in the root system. The results indicate resistance segregation both among and within families. Early cloning by minicutting demonstrated 100% efficiency, allowing the identification of 30 resistant individuals to occur simultaneously with the first multiplication cycle of these individuals, reducing the time and uncertainty involved in recovering superior materials. The methodology adopted is an effective strategy, allowing advances in guava breeding programs. Additionally, individuals resistant to M. enterolobii were observed in the hybrids P. guajava x P. cattleianum; P. cattleianum x P. guineense and P. guineense x P. cattleianum. Um dos entraves ao melhoramento genético de plantas arbóreas é o tempo decorrido entre a seleção dos genótipos superiores e a multiplicação dessas variedades. Este estudo se concentra em híbridos de Psidium, desenvolvidos para obter porta-enxertos ou novos copas resistentes ao nematoide Meloidogyne enterolobii. O uso de meios-irmãos ou sementes de híbridos desses materiais genéticos não permite manter o pefril genético de indivíduos resistentes, tornando os métodos de seleção destrutivos imprevisíveis. A propagação por miniestaquia de material juvenil de Psidium resulta em alta porcentagem de enraizamento, facilitando a clonagem de famílias segregantes e reduzindo o tempo necessário para produzir réplicas. Neste estudo, famílias segregantes para resistência a M. enterolobii foram clonadas usando a miniestaquia, com réplicas mantidas em minijardins clonais enquanto as matrizes originais foram inoculadas e avaliadas para reprodução de nematoides no sistema radicular.