Strategies for the recurrent selection program in tobacco breeding for green leaf yield

Abstract

In conducting a recurrent selection (RS) program in tobacco (Nicotiana tabacum L.), inbred and noninbred progenies as well as double‐haploid (DH) progenies can be used. There is also the possibility of recombining the selected progenies using half‐sib (HS) or full‐sib (FS) progenies. To choose the best RS strategy, the breeder's equation can be used. When using inbred progenies with an allelic frequency other than 50%, one of the genetic variance components is the genetic covariance between additive effects and homozygous dominance effects (D1). This component may present negative values and is part of the numerator in the equation for gain from selection (GS). Thus, the objective of this study was to estimate the genetic variance components in a tobacco population and compare the different strategies to conduct RS. From an RS population, HS, FS, and S1:2 inbred progenies were evaluated in different experiments. The dominance variance was null. In this condition, the estimate of D1 is not significant, meaning that D1 does not influence the GS in the RS program. With the obtained estimates, the GS was estimated for the seven different strategies for conducting the RS program. The use of DH lines in tobacco RS represents the best strategy. Other strategies allow expressive GS, such as the alternate use of inbred and FS progenies, for evaluation and FS progenies for recombination.

Viability of the use of inbred progenies in recurrent selection in perennial plants

“…Estimates of D 1 are not frequent in the literature. For tobacco leaf yield, the D1 estimates were negative but of small magnitude (Marques et al 2022). Nevertheless, in common bean, the estimates of D 1 , involving various traits, were negative in most cases (Souza and Ramalho 1995); this was likewise found in rice by Morais in 1992, cited by Ramalho et al (2012).…”

“…This greatly facilitates comparisons among the selection methods. The use of a constant variance for comparing IRS strategies was also adopted by Resende and Vencovsky (1992) and Resende (2015) in eucalyptus and Marques et al (2022) in tobacco. However, the variance adopted was based on data from experiments and considering a certain trait, which makes generalization slightly difficult.…”

“…Estimates of D 1 for several traits in annual plants, in addition to the nonexpressive magnitude, were negative (Ramalho et al 2012, Marques et al 2022. In eucalyptus, a single report of D 1 estimation showed that the value was also negative (Costa-Silva et al 2010).…”

Intrapopulation Recurrent Selection Strategies in Plant Breeding

“…This procedure is feasible because, in the case of eucalyptus, the pollen grains may be stored without losing viability. No reports of the employment of this procedure for eucalyptus were found, but it is routinely used in other species, such as tobacco (Marques et al 2022).…”

Comparison between doubled haploid lines and lines obtained via the bulk method in tobacco

“…This is because, from an F 2 or S 0 generation, it is necessary to carry out successive self-fertilization until most of the loci become homozygous. One of the most researched alternatives to accelerate this process is the use of doubled haploids (DH), which generates haploid individuals with duplicated chromosomes to obtain DH lines (DHL) (Chaikam et al 2019, Lenaerts et al 2019, Atlin and Econopouly 2021, Marques et al 2022. The use of DH has been widely researched and adopted in some crops such as wheat (Eliby et al 2022), rice (Naik et al 2017), corn (Mishra andRao 2016, Maqbool et al 2020), and tobacco (Nicotiana tabacum L.) (Hancock et al 2015.…”