Registration of three sweet sorghum lines with high tolerance to sorghum aphid (Melanaphis sorghi)

Authors: Knoll, Joseph - Joe; Uchimiya, Sophie; Hayes, Chad; PUNNURI, SOMASHEKHAR - Fort Valley State University; Harris-Shultz, Karen; Smith, Jesse

Submitted to: Journal of Plant Registrations
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/14/2023
Publication Date: 8/24/2023
Citation: Knoll, J.E., Uchimiya, S.M., Hayes, C.M., Punnuri, S.M., Harris-Shultz, K.R., Smith, J.S. 2023. Registration of three sweet sorghum lines with high tolerance to sorghum aphid (Melanaphis sorghi). Journal of Plant Registrations. 17:551-560. https://doi.org/10.1002/plr2.20310.
DOI: https://doi.org/10.1002/plr2.20310

Interpretive Summary: Sweet sorghum is grown for the sugary juice in its stalks, which is traditionally boiled to produce syrup, but it also has potential for use in manufacture of biofuels. Since 2013, an invasive insect, sorghum aphid (previously known as sugarcane aphid) has become a major pest of sorghum in North America. No existing sweet sorghum cultivars had resistance and insecticide options were limited. GTS1903, GTS1904, and GTS1905 sweet sorghums were developed with high levels of resistance to sorghum aphid. All three lines are derived from the initial cross A1N109 × No. 5 Gambela. A1N109 is a short, early-maturing sweet sorghum line, and No. 5 Gambela (PI 257599) is a tall, late-maturing sweet sorghum from Ethiopia, and is the source of the sorghum aphid resistance. GTS1903, GTS1904, and GTS1905 mature earlier than No. 5 Gambela. All three lines have shown good resistance to lodging and leaf anthracnose disease, caused by the fungus Colletotrichum sublineola. In four environments GTS1903, GTS1904, and GTS1905 sustained less aphid damage than the check cultivar Top 76-6, and in one environment they harbored significantly fewer aphids than the susceptible check. Under sorghum aphid infestation, juice brix (an estimate of % sugar content) averaged 17.0, 15.9, and 17.0°Bx for GTS1903, GTS1904, and GTS1905, respectively, with all three being greater than Top 76-6 (12.7°Bx). These lines were released by ARS in 2022 and should enable sweet sorghum growers to produce a crop without the need to spray insecticides to control sorghum aphid.

Technical Abstract: Sweet sorghum (Sorghum bicolor (L.) Moench) stalks contain sugary juice, which is used to produce syrup and has potential for biofuel production. Since 2013, sorghum aphid (Melanaphis sorghi, previously known as sugarcane aphid, M. sacchari) has become a major pest of sorghum in North America. No existing sweet sorghum cultivars are known to have resistance and insecticide options were limited. GTS1903, GTS1904, and GTS1905 (PI no’s ______, ______, and ______) represent the first publicly released sorghum aphid resistant sweet sorghum germplasm. All three are derived from the initial cross A1N109 × No. 5 Gambela. No. 5 Gambela (PI 257599) is the source of resistance. In four environments GTS1903, GTS1904, and GTS1905 sustained less aphid damage than the check cultivar Top 76-6, and in one environment they harbored significantly fewer aphids than the susceptible check. Under sorghum aphid infestation, juice brix, an estimate of sugar content, averaged 17.0, 15.9, and 17.0 °Bx for GTS1903, GTS1904, and GTS1905, respectively. All three were greater than Top 76-6 (12.7 °Bx). The juice of these three lines also contains greater trans-aconitic acid concentration than Top 76-6, which may contribute to sorghum aphid resistance. GTS1903, GTS1904, and GTS1905 flower approximately 74, 89, and 76 days after planting, respectively. GTS1905 is the tallest of these three, averaging 279 cm. All three lines have shown good resistance to leaf anthracnose (Colletotrichum sublineola).