Symptomatology of Barley Yellow Dwarf Virus-RMV Infection in Sweet Corn.

Infection of sweet corn (Zea mays L.) by barley yellow dwarf viruses (BYDVs) caused different symptoms on hybrids with shrunken-2 (sh-2) when compared with hybrids with sugary-1 (su-1) endosperm mutations. Sweet corn hybrids inoculated with BYDV-RMV in Urbana, IL, developed either yellow or red-purple leaf symptoms similar to those caused by phosphorus and/or potash deficiency (1). In a field trial near Rochelle, IL, 329 of 339 sweet corn hybrids naturally infected by BYDV exhibited one or the other of these symptoms. Eighteen of the hybrids with severe symptoms were tested for two strains of BYDVs in enzyme-linked immunosorbent assays (1). All of the hybrids tested were positive for BYDV-RMV; none were positive for BYDV-PAV. Symptoms on su-1 hybrids were typically characterized by dark red to purple coloration of leaf margins from the tip down to the mid-leaf. Leaves of sh-2 hybrids exhibited chlorosis in a similar pattern. A single sh-2 hybrid exhibited red-purple leaf symptoms, probably as a result of a crossover between the anthocyanin production (a1) and sh-2 genes, which are linked about 0.25 map units apart on chromosome 3 (2). Infection of sh-2 sweet corn hybrids by BYDV-RMV is most likely to induce chlorosis, whereas infection of su-1 sweet corn hybrids can result in either chlorosis or red-purple discoloration of leaves. Sweet corn hybrids with these symptoms should be tested for BYDVs, particularly the RMV strain. References: (1) R. L. C. Itnyre et al. Plant Dis. 83:566, 1999. (2) E. B. Mains. J. Hered. 40:21, 1948.