SWEET CORN SYNTHETICS AND COMPOSITES

Hawaii Foundation Seeds

Seed Availability: HFS can provide samples of most of these populations. Some are available only from the USDA-ARSNationalCenter for Germplasm Resource Preservation (NCGRP) in Ft. Collins, CO. Many have been provided to CIMMYT (International Maize and WheatResearchCenter) in Mexico.

PREFACE: Populations most extensively used in tropical breeding (Ref: Brewbaker 2014)

Hawaiian Supersweet #9(Hi bt COMP 3)

Hawaiian Supersweet Silver(Hi bt COMP 9)

Hawaiian Sugar

Hawaiian Supersweet #5(Hi sh2 COMP 2)

1. SUPERSWEET POPULATIONS BASED ON bt(brittle-1) GENE

Hi bt COMP 3p Hawaiian Supersweet #9; Composite selected for tenderness and green silk based on earlier Hi bt Comp 1 and Comp 2 (derived from Hawaiian Sugar variety x bt stock) (Brewbaker, 1977).

Hi bt COMP 4kComposite based on crosses of Haw'n Supersweet 9 x Suwan 1, segregating resistance to turcicum and downy mildew

Hi bt COMP 6oKalakoa Supersweet, a conversion of Hi bt COMP 3 to purple plant (A B Pl)

Hi bt COMP 9aaWhite endosperm conversion of Hi bt COMP 3 (y/y, not y8 or y11) with improved brace roots, kernel size, fusarium tolerance (= Hawaiian Supersweet Silver)

Hi bt SYN 2iSynthetic based on 15 sueprior bt inbreds

Hi bt SYN 3iSynthetic based on 3 outstanding inbreds from bt COMP 3

Hi bt SYN 7pSynthetic based on selected S5 inbreds from a composite based on bt COMP 3 crossed with hybrids of temperate x tropical field corn inbreds, selected for lodging and long ear

Hi bt SYN 9gSynthetic based on crosses of bt SYN 3 x six Hawaii synthetics of field corn inbreds, selected for a broad range of disease and pest resistance

Figure.Thai brittle-1 hybrid (to left) bred by Dr. Taweesak Pulam (to left) with fellow UH graduate Dr. Soon Kwon Kim and Prof. Brewbaker. Pulam’s hybrids derive from UH synthetics and dominate the huge Thai industry. Comparable temperate Chinese hybrid to right.

2. SUPERSWEET COMPOSITES BASED ON sh2 (shrunken-2) GENE

Hi sh2 COMP 2o Based on crosses of AA8 sh2 x tropical flint and sugary varieties; erect (= HawaiianSupersweet #5), broad range of disease and pest tolerance

Hi sh2 SYN 2nBased on SYN6 x Commercial sh2 hybrids selected for unusual flavor; very temperate in appearance

Hi sh2 SYN 6mBased on 2 prior SYNs involving 23 Hawaiian Sugar derived inbreds and 5 Mainland inbreds (e.g., 2256, R819, R839)

3. SWEET CORN POPULATIONS BASED ON su (sugary 1) GENE

Hi su COMP 6gStiff-stalked, low-eared composite from AA8 x N28 backcrossed to lines from Hawaiian Sugar, with genes Ht and Rp (not effective in Hawaii by 1980)

Hi su COMP 10iComposite based on Hi bt COMP 1 and tropical flints backcrossed to Hawaiian Sugar and selected for tenderness and Fusarium tolerance

Hi su COMP 12nBlue-seeded (ACRPr) composite based on BC7 to Hawaiian Sugar

Hi su COMP 13gComposite based on (Hawaiian Sugar x AA8) x Hi su SYN 3

Hi su COMP 14iNE-EDR COMP 1i, an exotic disease resistant composite of tropical and temperate sweet corns, under regional project NE124 (also available in bt and sh2 conversions)

Hi su SYN 3i Synthetic based on 16 outstanding inbreds from Hawaiian Sugar, that it mimics in appearance and productivity

Hi su SYN 4hSynthetic derived from 15 best singlecross hybrids of Hawaiian x Mainland inbreds such as 442, P39, P51 (formerly = Hi su COMP 1)

Hawaiian SugarOpen-pollinated variety developed by A. J. Mangelsdorf in 1945 from crosses of Caribbean flints x Golden Bantam variety; selected for tolerance to maize mosaic virus

4. SUPERSWEET COMPOSITE BASED ON bt2 (brittle-2) GENE

Hi bt2 COMP 1m Composite based on crosses of lines from Hawaiian Sugar with bt2 genetic stock(= Hawaiian Supersweet #6)

5. NE-EDR COMPOSITES, GERMPLASM RESERVOIRS FOR DISEASE RESISTANCE

NE-EDR su1 Composite based on 10 elite temperate sweet corn hybrids and 10 tropical, elite sugary-1 populations bred at U. Hawaii (see above), followed by 13 cycles of recurrent mass selection

NE-EDR bt1 Composite based on NE-EDR su1 Cycle 8 crossed to HibtCOMP3 followed by 5 cycles of backcrossing and 10 of selfing and recurrent mass selection; A superior germplasm resource

NE-EDR sh2 Composite based on NE-EDR su1 Cycle 8 crossed to temperate sh2 hybrids, followed by 5 cycles of backcrossing and 5 of sibbing in Hawaii and 4 of sibbing in Florida

6. WAXY (Vegetable corn) COMPOSITES

Hi wx COMP 1eComposite based on varieties and inbreds from SE Asia, selected for use as green vegetable (“mochi”)

Note: Suffixes a, b, c, etc. indicate the cycle of population improvement. AA8 is an inbred derived from Hawaiian Sugar. All composites and synthetics have the Mv allele for resistance to Maize Mosaic Virus, and varying levels of general resistance to fusarium kernel and seedling rot, common and polysora rusts, Northern leaf blight, MDMV, physoderma stalk rot, and earworms.

Relevant Publications:

Brewbaker, J.L. 1977. Hawaiian Super-sweet #9 corn. HortScience 12:355-356.

Brewbaker, J.L. 1998. Disease-resistant tropical sweet corn populations. HortScience 33:1262-1264.

Brewbaker, J.L. and B.T. Scully. 2002. NE-EDR su1 and NE-EDR bt1, disease-resistant sweet corn populations with sugary 1 and brittle 1 endosperms. HortScience 37:600-602.

Scully, B.T., J.L. Brewbaker, J.K. Pataky, W.F. Tracy and M.E. Smith. 2001. NE-EDR sh2; A yellow shrunken 2 sweet corn population with disease resistance from exotic sources. HortScfience 36:1149-1151.

Brewbaker, J. L. 2014. Breeding tropical vegetable corn. Plant Breeding Reviews 2014.

Performance data of Hi syns and comps.

Name Gene Color KD mm KW mg KRN EL cm PH cm EH cm MMV Rust Fus

HibtSYN2 / bt1 / Y / 9.9 / 125 / 14.7 / 12.3 / 179 / 56 / R / 2 39
HibtSYN3 / bt1 / Y / 10.0 / 101 / 14.7 / 11.3 / 169 / 56 / R / 2 41
HibtCOMP3 / bt1 / Y/W / 9.8 / 125 / 13.4 / 11.9 / 179 / 70 / R / 3 13
HibtCOMP4 / bt1 / Y / 9.4 / 112 / 13.2 / 10.8 / 182 / 75 / R / 2 55
HibtCOMP6 / bt1 / Y/W / 7.9 / 123 / 13.8 / 9.5 / 197 / 76 / R / 4 60
HibtSYN7 / bt1 / Y/W / 10.5 / 142 / 14.5 / 12.5 / 195 / 79 / R / 4 63
HibtCOMP8 / bt1 / Y / 9.4 / 117 / 13.5 / 12.0 / 184 / 68 / R / 3 57
Hibt2COMP1 / bt2 / Y / 8.6 / 146 / 13.5 / 11.2 / 191 / 63 / R / 5 69
Hish2SYN6 / sh2 / Y / 8.9 / 95 / 12.9 / 11.5 / 189 / 76 / R / 4 77
Hish2COMP2 / sh2 / Y / 9.5 / 158 / 13.5 / 14.2 / 190 / 77 / R / 4 44
HisuSYN3 / su1 / Y / 10.0 / 193 / 14.1 / 13.1 / 212 / 94 / R / 4 54
HisuSYN4 / su1 / Y / 9.8 / 234 / 13.4 / 12.0 / 203 / 79 / R / 4 52
HisuCOMP6 / su1 / Y / 9.6 / 195 / 13.7 / 13.1 / 207 / 74 / R / 5 41
HisuCOMP10 / su1 / Y/W / 9.4 / 211 / 13.6 / 13.6 / 203 / 80 / R / 3 19
HisuCOMP12 / su1 / B / 10.0 / 171 / 13.5 / 13.0 / 202 / 75 / R / 4 30
HisuCOMP13 / su1 / Y / 9.2 / 139 / 13.9 / 12.9 / 197 / 77 / R / 4 26
Mean / 9.4 / 154 / 13.6 / 12.2 / 195 / 76 / R / 3.6 47
Haw'n Sugar / su1 / Y / 8.9 / 222 / 12.9 / 13.7 / 206 / 93 / R / 5 24
Jubilee / su1 / Y / 10.8 / 158 / 14.8 / 12.5 / 138 / 49 / S / 8 93

MMV = maize mosaic virus; Rust = common rust (scores 1 good - 9 bad), Fus = Fusarium ear/kernel rot, % reduction under severe

infection. KD = Kernel depth, KW = kernel weight, KRN = kernel row number, EL = ear length, PH/EH = plant/ear height

(2015 web\sweetcorn syns&comps.doc)