Simultaneous cloning and selection of Psidium genotypes resistant to Meloidogyne enterolobii

Abstract

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.