|Gulya jr, Thomas|
Submitted to: Crop Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/14/2006
Publication Date: 7/1/2006
Citation: Jan, C.C., Gulya, T.J. 2006. Registration of a sunflower germplasm resistant to rust, downy mildew and virus. Crop Science. 46:1829. Interpretive Summary: Germplasm line TX16R, resistant to sunflower rust, downy mildew, and sunflower mosaic potyvirus (Sumv) were cooperatively developed and released in 2005. A population of wild Helianthus annuus L. designated as 'Texas-16' (TX16) was collected near Runn, Texas in 1999, and was found to possess resistance to sunflower rust, downy mildew, and mosaic potyvirus. In recent years, the discovery of new downy mildew and rust races capable of infecting resistant sunflower hybrids is accelerating at an alarming rate. TX16R will provide new and total resistance genes for these two major sunflower diseases and also provide protection if sunflower mosaic virus becomes economically important in sunflower production areas.
Technical Abstract: TX16 plants were first evaluated for resistance to a mixture of North American (NA) downy mildew isolates. The resistant plants were then inoculated with a mixture of NA rust isolates and sunflower mosaic potyvirus. The mixtures of downy mildew and rust isolates represent all major NA races and recent collections which will infect all commercial hybrids. Plants resistant to all three pathogens were pollinated with the inbred line HA 89 (PI 599773), and the resistant F1 plants were sib-pollinated to produce SIB F2. Resistant F3 families were identified and the bulked F4 seeds of 30 F3 families make up the release TX16R, with a pedigree of TX16/HA 89//TX16/HA 89, F4. Inheritance studies suggested that the resistance of each of the diseases is under the control of a single gene(s), and are at different loci. TX16R is homozygously resistant to all known sunflower downy mildew and rust races and sunflower potyvirus. TX16R is branched, with a plant height of 114 cm, segregating for black and gray-mottle seed coat color, with a 1000-seed weight of 4.3 grams, and 64% self-pollinated seed set.