Strawberry plant named ‘UC Golden Gate’

Abstract

UC Golden Gate is a Fusarium wilt-resistant day-neutral cultivar of a strawberry plant that produces flavorful, long shelf-life fruit.

Claims

1. A new and distinct cultivar of strawberry plant named UC Golden Gate, substantially as described and illustrated herein.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The colors in the photograph are depicted as nearly true as is reasonably possible to obtain in color reproductions of this type.

(2) FIG. 1 depicts fruit characteristics of UC Golden Gate.

(3) FIG. 2 shows 5-month old UC Golden Gate plants.

DETAILED DESCRIPTION

Botanical Description

(4) Botanical descriptors of UCD Golden Gate are provided in Table 1. The descriptors were collected in the spring and summer of 2022 from plants grown in Santa Maria, California. Plants evaluated in the spring were 6 months old. Plants evaluated in the summer were 8 months old. Colors are designated with reference to The Royal Horticultural Society (R.H.S.) Colour Chart, Sixth Edition, 2015. The characteristics of UC Golden Gate may vary in detail, depending upon environmental factors and culture conditions.

(5) TABLE-US-00001 TABLE 1 Range (Mean.sup.a) or Color (RHS Category Trait Unit Colour Designation) Foliar Plant height mm 280-330 (308) Foliar Plant spread mm 500-600 (560) Foliar Plant growth habit Semi-upright Foliar Plant, position of the foliage Above Plant inflorescence in relation to Foliar Mid-tier leaflet length mm 90-120 (106) Foliar Mid-tier leaflet width mm 120-140 (130) Foliar Petiole length mm 190-240 (216) Foliar Stipule core color color Strong Yellow Green (144 B) Foliar Stipule margin color color Strong Yellow Green (144 A) Foliar Stolons/nursery count 8-10 (9.0) mother plant Foliar Stolon color color Moderate Pink (51 D) Foliar Leaf color, adaxial color Greyish Olive Green (NN137 A) Foliar Leaf color, abaxial color Moderate Yellow Green (147 B) Foliar Leaf, blistering Medium Foliar Leaf, glossiness Medium Foliar Leaf, shape of base of Obtuse terminal leaflet Flower Arrangement of petals Overlapping Flower Stamen Present Flower Petal number count 5-7 (5) Flower Petal length mm 12-14 (13) Flower Petal width mm 12-14 (13) Flower Calyx diameter mm 20-35 (29) Flower Calyx, size in relation Larger to corolla Flower Corolla diameter mm 25-30 (27) Flower Sepal number count 10-14 (11) Flower Calyx Color color Moderate Olive Green (137 A) Flower Upper Petal Color color White (NN155 D) Flower Lower Petal Color color White (NN155 D) Flower Stamen number count 20-28 (24) Fruit Achene Color color Greenish Brilliant Yellow (4 A) Fruit Position of achenes Below surface Fruit Shape Conical Fruit Length mm 40-48 (44) Fruit Width mm 35-40 (38) Fruit Size of hollow core mm 2-12 (7) Fruit External Fruit (exterior) color Moderate Red (color) (N45 A) & Vivid Red (45 A) Fruit Fruit flesh color Vivid Reddish (color) Orange (33 A) Fruit Fruit core color Strong Yellowish (color) Pink (37 A&B) & Moderate Reddish Orange (35 A&B) Fruit Fruit size g/fruit 22-32 (27) .sup.aMean values were estimated from nine samples per trait.

(6) The time of the beginning of flowering is late January, 3 months post-planting.

Marker-Assisted Selection

(7) Marker-assisted selection was employed to identify individuals predicted to be heterozygous or homozygous for the dominant (favorable) alleles for a Fusarium wilt resistance locus (FW1) and the PERPETUAL FLOWERING (PF) locus. The genotypes predicted by PF- and FW-linked SNPs for UC Golden Gate were PFpf and FW1fw1. The predicted genotypes were confirmed with a 50,000 Aximo SNP array (Hardigan et al, 2020, supra).

Fusarium Wilt Resistance

(8) The dominant FW1 allele confers resistance to Fusarium wilt race 1, cause by Fusarium oxysporum f.sp. fragariae. Fusarium resistance was further tested by three years of replicated testing of bare-root plants artificially inoculated with AMP132, a race 1 isolate of the pathogen. The resistance of UC Golden Gate to Fusarium wilt was compared to that of UC Keystone, San Andreas (U.S. Pat. No. 19,975), which is heterozygous FW1fw1 Fusarium wilt-resistant; and to susceptible (homozygous recessive (fw1fw1)) varieties Monterey, UCD Royal Royce, and UCD Valiant. UC Keystone, UC Golden Gate, and San Andreas were symptomless in these Fusarium wilt screening trials over three years (Table 2) with mean disease scores in the highly resistant range that were not significantly different from one another. The mean disease scores for Monterey, UCD Royal Royce, and UCD Valiant were significantly greater than for UC Golden Gate (ordinal scores increase as disease symptoms increase).

(9) UC Golden Gate resistance to Verticillium wilt and Phytophthora crown rot (PhCR) was also evaluated (Table 2) in comparison to UC Keystone, Monterey, UCD Royal Royce, and UCD Valiant. UC Keystone and UC Golden Gate are moderately resistant to these diseases. Their resistance phenotypes are not significantly different from San Andreas and Monterey, and other commercially important cultivars.

(10) TABLE-US-00002 TABLE 2 Across-year estimated-marginal means (EMMs).sup.a for Fusarium wilt, Verticillium wilt, and Phytophthora crown rot (PhCR) resistance scores.sup.b for UC Keystone, UC Golden Gate, UCD Valiant, UCD Royal Royce, San Andreas, and Monterey observed in 2019-20, 2020-21, and 2021-22 disease resistance screening trials in Davis, CA. Test Check Cultivar Cultivar Disease.sup.c Check Cultivar EMM.sup.d EMM t.sup.e p-value.sup.f Fusarium UCD Valiant 1.17 2.88 ?4.02 0.0001 Wilt UCD Royal 2.98 ?4.28 0.0001 Royce San Andreas 1.15 0.04 0.97 Monterey 3.36 ?4.81 <0.0001 UC Keystone 1.25 ?0.19 0.85 Verticillium UCD Valiant 1.97 1.93 0.09 0.93 Wilt UCD Royal 2.31 ?0.81 0.42 Royce San Andreas 1.29 0.99 0.33 Monterey 2.36 ?0.77 0.45 UC Keystone 2.12 ?0.34 0.74 Phytophthora UCD Valiant 2.25 2.25 0.00 1.00 Crown Rot UCD Royal 2.33 ?0.16 0.87 Royce San Andreas 1.83 0.59 0.56 Monterey 3.07 ?1.23 0.22 UC Keystone 2.44 ?0.34 0.73 .sup.aEMMs were estimated from four replications/entry/year over three years (12 observations/entry), except for Fusarium, where additional screening in 2022 resulted in 24 observations/entry. .sup.bThe ordinal symptom rating scales were identical for each disease: 1 = highly resistant, 2 = moderately resistant, 3 = moderately susceptible, 4 = susceptible, and 5 = highly susceptible. .sup.cThe fungal pathogens causing these diseases are Fusarium oxysporum f. sp. fragariae (Fusarium wilt), Verticillium dahliae (Verticillium wilt), Phytophthora cactorum (Phytophthora crown rot). .sup.dThe test cultivars were UC Keystone (shown in the upper half of the table) and UC Golden Gate (shown in the lower half of the table). .sup.et-statistics for linear contrasts (EMM.sub.1-EMM.sub.2) between the EMMs for UC Keystone or UC Golden Gate and check cultivars. .sup.fThe probability of a greater t-statistic by chance for tests of the null hypothesis of no difference between EMMs (H.sub.0: EMM.sub.1 = EMM.sub.2).

Photoperiod Insensitive Phenotype

(11) The dominant PF allele is necessary for photoperiod insensitive flowering in cultivated strawberry. The predicted photoperiod insensitive phenotype of UC Golden Gate was confirmed through three years of on-farm testing in Santa Maria, California and Prunedale, California. UC Golden Gate consistently flowered and fruited throughout the commercial day-neutral growing seasons in Nipomo (35.0N) and Prunedale (36.8N) where daylengths ranged from 9.8 to 14.7 hours.

Field Evaluations

(12) Three seasons of advanced testing of selected day-neutral hybrids originating from the 2017-18 breeding cycle, starting with ninety-four selections in 2018-19 and finishing with six sections in 2021-22, one of which was UC Golden Gate, were completed. Comparison cultivars were UC Keystone, Monterey, UCD Royal Royce, and UCD Valiant.

(13) Clones (asexually propagated bare-root plants) for the first year of testing (Phase I in 2018-19) were produced in Winters, California. Clones for subsequent years of testing (Phase II in 2019-20 and 2020-21 and Phase III in 2021-22 and 2022-23) were produced in commercial high-elevation nurseries (Dorris, California) using standard production and propagation practices and post-harvest chilling treatments optimized for the day-neutral market segment. Clones were harvested in late October, trimmed, and directly planted in late October and early November of each year.

(14) For on-farm yield trials, plants were grown in two 10-plant plots in Phase I and two 20-plant plots in Phase II, and two 500-1,000-plant strips in Phase III yield trials. The plots were arranged in randomized complete blocks experiment designs in commercial production fields. These experiments were grown using the management practices, bed configurations, plastic mulches, planting densities, planting dates, irrigation, fertilization, and pesticide application decisions and schedules, and harvest schedules of our cooperators.

(15) Marketable fruit yield, count, and size were recorded at each harvest. Collection and analysis of 18,526 observations were employed for these traits to support statistical analyses.

Fruit Quality

(16) Fruit from early and peak season harvests from every trial were performed to phenotype hybrids for firmness, total soluble solids (TSS=Brix), and titratable acidity (TA). The peak and late season fruit from four environments were stored at 4? C. and screened for post-harvest perishability over 14 days. These samples were phenotyped for weight, TSS, TA, firmness, gloss, and leakage at 0, 7, and 14 days post-harvest (DPH). Over three growing seasons, 2,273 phenotypic observations were collected for fruit quality traits at harvest to support statistical analyses and selection decisions.

(17) Plants were assessed for flavor and aroma through informal hedonic testing in the field and laboratory by various individuals, including growers, shippers, and others. Although specific volatile organic compounds (VOCs) known to affect aroma were not selected for, selection pressure for enhanced flavor and aroma was applied and VOC profiles were analyzed for 152 cultivars and other hybrids over two years of on-farm testing. UC Golden Gate was among the hybrids phenotyped for VOC. These data were used to assess the effect of subjective olfactory and gustatory assessments on aroma profile changes. VOC analyses were performed using solid phase microextraction (SPME) gas chromatography-mass spectroscopy of fruit samples collected from early and peak season harvests over two years from on-farm yield trials in Santa Maria and Prunedale, California. Although at least 360 VOCs have been identified in developing strawberry receptacles, aroma and flavor are dominated by fewer than 10. Data for approximately 52 VOCs affecting aroma (58,488 phenotypic observations) were collected and analyzed to support statistical analyses. Data for three VOCs (?-decalactone, mesifurane, and linalool) that are predicted to contribute towards the improved flavor of UC Keystone and UC Golden Gate are provided.

(18) The fruit quality of UC Golden Gate equals or exceeds the fruit quality and shelf life standards of long shelf life (LSL) cultivars designed for prolonged cold storage and long-distance shipping. Table 3 provides a comparison of the cumulative marketable fruit yields and other fruit traits.

(19) TABLE-US-00003 TABLE 3 Across-environment estimated marginal means (EMMs) for cumulative marketable fruit yield and other fruit traits for UC Golden Gate and comparison cultivars grown on commercial farms in Nipoomo and Prunedale, CA over three growing seasons (2019-20 to 2021-22).sup.a. UC Com- Golden parison Comparison Gate Cultivar p- Trait.sup.a Cultivar EMM EMM t.sup.b value.sup.c Yield (lb/ Monterey 95,730 88,323 0.68 0.50 acre) UCD Valiant 91,783 0.36 0.72 UCD Royal 89,044 0.61 0.54 Royce UC Keystone 103,710 ?0.73 0.47 Size (g/ Monterey 28.7 29.7 ?1.88 0.06 fruit) UCD Valiant 33.0 ?7.41 <0.0001 UCD Royal 28.8 ?0.18 0.85 Royce UC Keystone 28.0 1.20 0.23 Firmness Monterey 303.7 239.1 4.79 <0.0001 (g-force) UCD Valiant 297.1 0.46 0.65 UCD Royal 349.9 ?3.22 0.002 Royce UC Keystone 260.6 3.25 0.002 TSS (%) Monterey 7.84 8.89 ?5.92 <0.0001 UCD Valiant 7.37 2.55 0.01 UCD Royal 7.57 1.49 0.14 Royce UC Keystone 8.29 ?2.59 0.01 TA (%) Monterey 0.85 0.76 3.73 0.0005 UCD Valiant 0.82 1.37 0.18 UCD Royal 0.82 1.46 0.15 Royce UC Keystone 0.77 4.21 0.0001 TSS/TA Monterey 9.45 10.44 ?7.505 <0.0001 UCD Valiant 9.20 0.79 0.43 UCD Royal 9.55 ?0.34 0.73 Royce UC Keystone 11.01 ?5.19 <0.0001 .sup.aCumulative marketable fruit yields were estimated from fruit harvested on commercial schedules (once or twice weekly) over the entire day-neutral growing season on each farm. Fruit firmness, total soluble solids (TSS), and titratable acidity (TA) were measured from multiple fruit/replication sampled from two harvests/trial. EMMs and test statistics were estimated from the phenotypes of fruit harvested from two 24-plantplots/entry/environment. .sup.bt-statistics for linear contrasts (EMM.sub.1 ? EMM.sub.2) between UC Golden Gate and check cultivar EMMs. .sup.cThe probability of a greater t-statistic by chance for tests of the null hypothesis of no difference between EMMs (H.sub.0: EMM.sub.1 = EMM.sub.2).

(20) UC Keystone and UC Golden Gate produced large fruit (28.0 to 28.7 g/fruit) in the on-farm trials (Table 3). Their fruit weights were in the normal range for mass-produced day-neutral cultivars in California.

(21) UC Golden Gate fruit were significantly firmer (303.7 g-force) than UC Keystone (260.6 g-force; p=0,0002) and Monterey (239.1 g-force; p<0.0001). The firmness of these cultivars exceeded the threshold (>230 g-force) necessary for minimizing harvest and post-harvest losses and delivering a high quality product to markets over long distances.

(22) The sweetness and sourness profiles of UC Keystone and UC Golden Gate are slightly different. Total soluble solids (TSS) were slightly greater for UC Keystone (8.33) than UC Golden Gate (7.85; p=0.008), whereas titratable acidity (TA) was greater for UC Golden Gate (0.83) than UC Keystone (0.74; p=0.0003). The TSS/TA ratio (a measure of perceived sweetness) was significantly greater for UC Keystone (11.66) than UC Golden Gate (9.86; p=0.0001). The TSS/TA ratio for UC Keystone was slightly lower but not significantly different from Monterey, whereas the TSS/TA ratio for UC Golden Gate was significantly lower than Monterey (p<0.0001). Hence, the sweetness and perceived sweetness ratings for UC Keystone and Monterey were essentially identical and greater than UC Golden Gate. The slightly sweeter qualities of UC Keystone and slightly tarter qualities of UC Golden Gate have both been well received by growers and taste testers. The flavor improvements of UC Keystone and UC Golden Gate over UCD Royal Royce and UCD Valiant were partly driven by increased TSS and TSS/TA ratios; however, as previously noted, UC Golden Gate falls near those cultivars and below Monterey in sweetness and TSS/TA ratio.

(23) UC Keystone and UC Golden Gate were identified to have improved aroma from subjective olfactory and gustatory assessments of fruit. Solid phase microextraction (SPME) GC-MS analyses of volatile organic compounds (Table 4) suggested that part of the improved flavor of UC Keystone and UC Golden Gate can be attributed to an increase in ?-decalactone (5-hexyloxolan-2-one), the most abundant lactone found in strawberry. This VOC, which imparts an intense-peach flavor, is abundant in Albion (U.S. Plant Pat. No. 16,228) and absent in Monterey.

(24) TABLE-US-00004 TABLE 4 Across-year estimated-marginal means (EMMs).sup.a for ?-decalactone, mesifurane, and linalool concentrations? in ripe fruit of UC Keystone, UC Golden Gate, and comparison cultivars harvested in 2020-21 and 2021-22 from on-farm yield trials in Nipomo, CA. ?-decalactone mesifurane linalool Cultivar EMM EMM EMM Monterey 0 1,025,275 58,682 UCD Royal Royce 7,253 247,148 0 UCD Valiant 14,406 213,015 1,374 UC Keystone 34,740 156,584 20,783 UC Golden Gate 7,273 241,300 6,265 Albion 132,592 991,288 17,942 LSD.sup.b 109,763 146,678 26,860 .sup.aEMMs were estimated from fruit sampled from two 20- or 40-plant plots/entry/year. The relative concentrations of volatile organic compounds (ng/g dry weight) were estimated from the raw solid phase microextraction (SPME) GC-MS data (peak area in counts) and normalized samples. .sup.bLeast significant differences are shown for a false-positive probability of p = 0.05.

(25) UC Keystone and UC Golden Gate meet or exceed the shelf life requirements for mass-produced cultivars developed for cold storage and long distance shipping in California. Minimal declines were observed in the deterioration of fruit firmness and other fruit quality traits over 14 days of post-harvest cold storage using fruit sampled from peak and late season harvests No statistically significant differences for fruit weight, TSS, TA, or leakage between UC Keystone and UC Golden Gate and comparison cultivars were observed.

Fruit Production CharacteristicsField Trials

(26) The number of harvests ranged from 40 to 61 in each trial to assess UC Golden Gate fruit production in comparison to that of UC Keystone, Monterey, UCD Royal Royce, and UCD Valiant. Marketable fruit yield, count, and size were recorded at each harvest. Collection and analysis of 18,526 observations was performed for these traits to support statistical analyses.

(27) Statistics are shown for linear contrasts between the estimated marginal means (EMMs) for UC Keystone, UC Golden Gate, and comparison cultivars across environment (2 locations 3 years) and for individual environments to highlight variation in planting dates, the number of harvests, harvest ranges, and production practices (Table 5). EMMs were estimated from two 20-plant plots (replications)/entry/environment in 2020 and 2021 and two 40-plant plots in 2022.

(28) TABLE-US-00005 TABLE 5 Within environment estimated marginal means (EMMs) for cumulative marketable fruit yield for UC Golden Gate and check cultivars grown on farms in coastal California over three growing seasons (2019-20 to 2021-22).sup.a. UC Golden Compare Gate Cultivar Comparison EMM EMM Location Season Cultivar (lb/a) (lb/a) Nipomo 2019-20 Monterey 82,971 64,797 UCD Royal Royce 79,625 UCD Valiant 90,853 UC Keystone 88,028 Prunedale 219-020 Monterey 103,065 73,300 UCD Royal Royce 101,146 UCD Valiant 81,841 UC Keystone 103,149 Nipomo 2020-21 Monterey 99,935 70,682 UCD Royal Royce 93,142 UCD Valiant 107,279 UC Keystone 99,214 Prunedale 202-021 Monterey 123,669 97,546 UCD Royal Royce 128,842 UCD Valiant 119,684 UC Keystone 115,908 Nipomo 2021-22 Monterey 59,740 69,976 UCD Royal Royce 39,241 UCD Valiant 57,602 UC Keystone 56,691 Prunedale 2021-22 Monterey 104,999 152,127 UCD Royal Royce 92,924 UCD Valiant 93,437 UC Keystone 158,914 Yield Change Location (%).sup.b t.sup.c p-value.sup.d Nipomo 28.0 2.89 0.02 4.2 0.41 0.69 ?8.7 ?1.26 0.24 ?5.7 ?0.84 0.42 Prunedale 40.6 5.55 0.0002 1.9 0.36 0.73 25.9 3.96 0.002 ?0.1 ?0.02 0.99 Nipomo 41.4 3.24 0.01 7.3 0.75 0.47 ?6.8 ?0.81 0.44 0.7 0.08 0.94 Prunedale 26.8 4.15 0.002 ?4.0 ?0.82 0.43 3.3 0.63 0.54 6.7 1.23 0.24 Nipomo ?14.6 ?3.25 0.004 52.2 5.64 <0.0001 3.7 0.59 0.56 5.4 0.97 0.34 Prunedale ?31.0 ?7.06 <0.0001 13.0 1.57 0.13 12.4 1.50 0.15 ?33.9 ?8.08 <0.0001 .sup.aLinear contrasts between estimated marginal means (EMMs) for UC Golden Gate and comparison cultivars were estimated for each environment. EMMs were estimated from two 20- or 40-plant plots/entry within each environment. Cumulative marketable fruit yields were estimated from fruit harvested on commercial schedules (once or twice weekly) over the entire day-neutral growing season on each farm. .sup.bThe yield change percentage was estimated by (EMM.sub.1 ? EMM.sub.2)/EMM.sub.2 ? 100. .sup.ct-statistics for linear contrasts (EMM.sub.1 ? EMM.sub.2) between the EMMs for UC Golden Gate and comparison cultivars. .sup.dThe probability of a greater t-statistic by chance for tests of the null hypothesis of no difference between EMMs (H.sub.0: EMM.sub.1 = EMM.sub.2).

(29) UC Keystone and UC Golden Gate were the highest yielding cultivars in these trials. When averaged across environments, however, the yields of UC Keystone, UC Golden Gate, and the three comparison cultivars were not statistically different. Thus, UC Golden Gate has yields at least equal to the Fusarium wilt-susceptible comparison cultivars.

(30) The cumulative marketable fruit yields of UC Golden Gate were 18,174 to 29,765 lb/a greater than Monterey in four environments and 10,236 to 47,915 lb/a less than Monterey in two environments (Table 5).

(31) The cumulative marketable yield plots for each environment highlight the differences among cultivars and growing seasons. The yields of Monterey were below and separated from UC Keystone, UC Golden Gate, and the other comparison cultivars in the first two growing seasons. Yields dropped in the last growing season (2021-22) in Nipomo especially compared to previous years, with less separation among cultivars.

(32) The cumulative marketable fruit yields of UC Keystone and UC Golden Gate were not significantly different in five of six test environments or across environments (Tables 3 and 5). The yield of UC Keystone was significantly greater than UC Golden Gate in one environment (Prunedale 2021-2022). The reasons for yield decreases for UC Golden Gate, UCD Royal Royce, and UCD Valiant in the 2021-22 Prunedale trial were not clear. The affected plants ultimately recovered, however, and produced an abundance of fruit later in the season.

(33) UC Golden Gate is thus a highly productive Fusarium wilt resistant cultivar for the day-neutral segment that meets or exceeds the shelf life, flavor, and fruit quality characteristics of Monterey.