Genetic Variation and Gains in Resistance of Strawberry to Colletotrichum gloeosporioides

Abstract

Anthracnose crown rot is an important disease of strawberry primarily caused by Colletotrichum gloeosporioides in Florida and North Carolina. Information on the magnitude of additive and nonadditive genetic variation is required to define breeding strategies and to estimate potential genetic gains. However, little is known about the genetic control of resistance and its utility in breeding. Our objectives were to obtain estimates of heritabilities and of components of genetic variances, genotype-environment interactions, and gains for resistance, and to examine the effects of locations and transplant types on the estimates. An incomplete diallel mating design generated 42 full-sib families, which were propagated in plugs from seed (seedling tests) and as bare-root runner plants (clonal tests) of different genotypes of the same families. Both seedlings and clones were inoculated with C. gloeosporioides under field conditions in North Carolina and Florida during the 2010-11 season. Narrow-sense heritability (h(2)) and broad-sense heritability (H(2)) for both clones and seedlings were higher at the North Carolina location (h(2) = 0.34 to 0.62 and H(2) = 0.46 to 0.85) than at the Florida location (h(2) = 0.16 to 0.22 and H(2) = 0.37 to 0.46). Likewise, the seedling tests showed higher genetic control than the clonal tests at both locations. Estimates of dominance variance were approximately one-third of the additive variance at North Carolina and were even larger at Florida. Epistasis was negative at both locations and assumed zero for heritability (H(2)) calculations. Genotype-environment interactions were different by transplant type, suggesting rank changes across locations. 'Pelican' was the most resistant parent at both locations, followed by 'NCH09-68' at the NC location and 'Winter Dawn' at the Florida location. Selection and deployment of the most resistant clone within each of the five best families is estimated to produce average genetic gains of 53.0 and 73.7% at the North Carolina and Florida locations, respectively.

Comparison of Whole Plant and Detached Leaf Screening Techniques for Identifying Anthracnose Resistance in Strawberry Plants

“…Strawberry cultivars were either purchased from commercial strawberry nurseries or obtained as in vitro plantlets from the USDA-ARS Germplasm Repository, Corvallis, OR. Thirty-one cultivars [including cultivars with known anthracnose reactions: Elsanta, susceptible to C. acutatum (Denoyes and Baudry 1995;Denoyes-Rothan and Guérin 1996), Chandler, susceptible to C. fragariae and C. gloeosporioides (Chang and Smith 2007), and Pelican, resistant to C. fragariae and C. gloeosporioides (Osorio et al 2014;Smith et al 1998)] and 50 MSUS clones (including US70, US159, and US292, resistant to C. fragariae and C. gloeosporioides) were established in 10-cm plastic pots in a 1:1 mixture of Jiffy-Mix (Jiffy Products of America Inc., West Chicago, IL) and sand. Plants used in the study were propagated by rooting young runner plants in the Jiffy-Mix:sand potting mixture and maintained in a greenhouse at 28°C ± 10°C with a 16-h photoperiod, and fertilized every 16 weeks with 0.6 grams/pot of Osmocote (ICL Specialty Fertilizers -North America, Dublin, OH)14-14-14 time-released fertilizer.…”

“…Successful disease screening of large plant populations requires that the disease response be assessed with accurate and reproducible techniques. Although whole plant inoculation assays to screen for anthracnose resistance have been demonstrated to be accurate and reproducible (Chang and Smith 2007;Lewers et al 2007;Osorio et al 2014;Smith 2008), they are time-consuming, and plants are often killed by the disease, which can present a problem for the breeder because the germplasm may have possessed other desirable horticultural traits. Screening for anthracnose resistance using detached strawberry leaves is an alternative to inoculating whole plants and can possibly eliminate the destruction of desirable germplasm.…”

Pedigree-Based Analysis in a Multiparental Population of Octoploid Strawberry Reveals QTL Alleles Conferring Resistance toPhytophthora cactorum

“…$Z_1$ to $Z_5$ are known design matrices relating the observations in $y$ to effects in $d,p,a,f$, and $c$, respectively. The vectors, design matrices, and random components are according to the clonal test in Osorio et al (2014), with the exception that a term for the effect of plots within beds $\left(Z_{2}p\right)$ was included in our analyses to account for the variation along the beds. Univariate analyses for the production traits were analyzed with the same linear model except that the model was fitted to the observed continuous data and included the initial weight of runner plants as a fixed covariate effect.…”

Application of Volatile Antifungal Plant Essential Oils for Controlling Pepper Fruit Anthracnose by Colletotrichum gloeosporioides

“…Rain-proofed fields for planting were suggested to protect pepper fruits against anthracnose occurring rainy period-dependently ( Jee et al, 2010 ; Kwon and Lee, 1999 ). Recently, genetic regulations of disease resistance for resistant cultivar breeding have been investigated in alfalfa, common bean and strawberry to anthracnose caused by C. trifolii , C. linthemuthianum and C. gloeosporioides , respectively ( Ferreira et al, 2012 ; Osorio et al, 2014 ; Yang et al, 2007 ). However, limited genetic resources are available for anthracnose resistance of pepper plants ( Kim et al, 2007 , 2010 ; Mahasuk et al, 2009 ).…”