Inheritance of a Chlorophyll Deficiency in Hazelnut

A chlorophyll deficiency expressed as yellowing of leaves was observed in hazelnut (Corylus avellana L.) progenies. Segregation ratios approximated 3 green : 1 yellow, indicating control by a single recessive gene designated chlorophyll deficient #1, for which the symbol c, is proposed. ‘Barcelona’, ‘Butler’, ‘Compton’, ‘Lansing’, Willamette’, and the ornamental selection ‘Redleaf #3’ are heterozygous. Pedigree analysis strongly suggests that all heteroxygotes inherited the recessive allele from ‘Barcelona’. A cross of ‘Barcelona’ with the yellow-leafed ornamental Corylus avellana L. var. aurea Kirchn. produced no yellow-leafed seedlings, indicating that the chlorophyll deficiencies from these two sources are controlled by different loci. Progenies segregating simultaneously for this trait and the gene controlling presence of anthocyanin indicated that the two traits are inherited independently. Seedlings deficient in chlorophyll but with anthocyanin were able to survive under field conditions, while leaves of yellow-leafed seedlings lacking anthocyanin became scorched and the trees died. Chlorophyll deficiencies commonly segregate in progenies of naturally cross-pollinated and clonally propagated plants and may be expressed as striped, variegated, albino, Received for publication 15 Feb. 1991. Oregon Agricultural Experiment Station Technical Paper no. 9346. This research was supported with funds from the Oregon Hazelnut Commission. We thank David C. Smith and Loretta K. Brenner for technical assistance. The cost of publishing this paper was defrayed in part by the payment of page charges. Under postal regulations, this paper therefore must be hereby marked advertisement solely to indicate this fact. HORT yellow, yellow-green, or pale-green leaves. Chlorophyll deficiencies are often lethal or sublethal and are generally monogenic recessives. Many such mutants have been described in maize (Neuffer et al., 1968). Among the tree fruits, albinos have been reported in apple (Brown, 1975; Hall and Crane, 1933), peach (Bailey and French, 1941), and sweet cherry (Kerr, 1963). Klein et al. (1963) reported that 13 of 20 apple genotypes studied were heterozygous for a pale-green lethal. In this paper, we describe a monogenic recessive chlorophyll deficiency in seedlings of ‘Barcelona’ hazelnut and demonstrate that it is inherited independently of the presence SCIENCE, VOL. 26(11), NOVEMBER 1991 Table 1. Segregation for green and yellow leaf color in hazelnut crosses. The first two digits of the progeny code indicate the year of the cross and the last three digits, the number of the cross. Numbered selections from the Oregon State Univ. breeding program are listed by location of the original seedling tree (row number.tree number). Table 2. Pedigrees of selections heterozygous at the chlorophyll deficient #1 locus Genotypes known to be heterozygous are in italics. Numbered selections from the Oregon State Univ. breeding program are listed by location of the original seedling tree (row number.tree number). of anthocyanin and not allelic to the chlorophyll deficiency found in Corylus avellana var. aurea. The progenies studied were produced from controlled crosses as part of a hazelnut breeding program. Following stratification for 3 to 4 months at ≈ 4C, seeds were planted in flats in the greenhouse. Progenies segregating for leaf color were noted and segregation ratios were scored 5 to 6 weeks after planting. Chi-square goodness-of-fit tests were performed for an expected ratio of 3 green : 1 yellow. For progenies segregating simultaneously for the chlorophyll deficiency and the presence of anthocyanin, ratios were tested separately for each trait, and a goodness-offit test to a combined 3 red : 3 green : 1 redyellow : 1 yellow ratio was performed. A contingency chi-square test was used to detect deviations from expectations based on independent assortment. Whereas 10 of the 11 progenies fit a 3 green : 1 yellow segregation expected for a single recessive gene, progeny 77026 had a surplus of yellow-leafed seedlings (Table 1). We propose the symbol c1 for this gene, designated chlorophyll deficient #1 to indicate that it is the first such gene reported in hazelnut. Pedigrees of parents segregating for yellow leaves were examined to determine if heterozygotes had a common ancestor (Table Table 3. Progenies segregating simultaneously for The first two digits of the progeny code indicate th Numbered selections from the Oregon State Univ. Expected ratio 3 green : 1 yellow. Expected ratio 1 red : nonred. Expected ratio 3 red : 3 green : 1 red-yellow : 1 y Contingency test for independence. HORTSCIENCE, VOL. 26(11), NOVEMBER 2). ‘Barcelona’ is heterozygous (C1c1) and transmitted the c, allele to many of its offspring. Other heterozygotes include ‘Butler’, ‘Compton’, and ‘Lansing #1’, grower selections that originated in Oregon, where ‘Barcelona’ is the leading cultivar and ‘Daviana’ the leading pollinizer. All three have long been suspected of being hybrids between ‘Barcelona’ and ‘Daviana’, as they are morphologically very similar to seedlings resulting from the controlled cross. Analysis of incompatibility alleles has shown that each has one allele in common with ‘Barcelona’ (S1S2) and S3 in common with ‘Daviana’ (Mehlenbacher and Thompson, 1988). It is very likely that the three grower selections inherited the yellow-leaf allele from ‘Barcelona’. Twenty-one numbered selections and the new cultivar Willamette, a seedling from the cross ‘Montebello’ × ‘Compton’, are also heterozygous. In all cases, pedigrees indicate that heterozygotes inherited the chlorophyll-deficient allele either directly from ‘Barcelona’ or indirectly through one of the grower selections noted. A cross of ‘Barcelona’ with C. avellana var. aurea, the yellow-leafed ornamental ‘Goldhasel’ described by Goeschke (1887), produced 94 seedlings. All of them had green leaves, indicating that the two chlorophyll deficiencies are controlled by different loci. This result is consistent with the differences in chlochlorophyll deficiency and presence of anthocyanin. e year of the cross and the last three digits the numb breeding program arc listed by location of the origina