Progress in Precision Breeding for Genetic Improvement of Muscadine Grapevine

Precision breeding (PB), in which only defined genetic elements from sexually-compatible parents are utilized, is a logical extension of conventional breeding (CB), inasmuch as it is fully consistent with the plant lifecycle. PB builds upon decades of research aimed at bypassing the disruption of sexual reproduction (meiosis) by allowing gene insertion to be accomplished via the significantly more stable and predictable mitotic cell division pathway. For an increasing number of crop plants, it is now possible to transfer only pre-tested genes and other genetic elements that express known traits among sexually-compatible relatives. The PB approach has particular promise for muscadine grape (Vitis rotundifolia), which is unique among all grapes due to its ability to thrive in the southeastern United States. However, while vegetatively very resistant to both bacterial (Pierce’s disease) and a host of fungal diseases, the ripe berries remain to be highly susceptible to rot fungi, to the extent that muscadine fruit cannot be stored long enough for wide distribution. In ongoing studies to increase shelf-life, a number of putative disease resistance genes have been inserted into several mainstream muscadine cultivars. Plants are being placed into three disparate field test sites. Fruiting of the first putatively rot resistant line will commence in Summer 2015. A number of new lines containing various grape-derived genes are being readied for field tests. The taste of muscadine fruit tends to be highly desirable to a wide range of consumers. Extending its shelf life will make muscadine grape available to a greatly expanded geographic range of clientele.