Transfer of Reniform Nematode Resistance from Diploid Cotton Species to Tetraploid Cultivated Cotton. (S-avila274808-oral)
Authors:
C. Avila* - Univ. of Arkansas J. Stewart - Univ. of Arkansas
Abstract:
The reniform nematode (Rotylenchulus reniformis) has become a serious threat to cotton (Gossypium hirsutum L.) production in Arkansas and Mid-South because yield losses in the infested fields may exceed 50% under stress conditions. The most cost effective method for pest management is host plant resistance; however, no commercial cultivars tested to date have shown resistance. Robbins and Stewart (1996) identified a number of sources of resistance within G. arboreum (A2), G.
herbaceum (A1), and G. longicalyx (F1). These sources are diploid species;
therefore, the material must be genetically enhanced for use in tetraploid cultivated cotton. The objective of this project was to develop hybrid materials between
resistant reniform nematode diploid cottons and tetraploid cultivated cotton. Three basic steps where followed: (1) Diploid hybridization, (2) chromosome doubling, and (3) introgression into upland cotton. In the first step, A-genome reniform nematode resistant species were crossed with a D-genome species to produce diploid interspecies hybrids. Colchicine was applied at different doses (1%, 10 and 20 ppm on the axillary buds, germinating seed and rooting cuttings, respectively) to double the number of chromosomes. In the final step, the synthetic tetraploid
produced was crossed with upland cotton to transfer the reniform nematode resistance. Two triple hybrids have been produced, one from the cross of
commercial cultivar DP491 and the other with Delta Pearl cultivar with a doubled chimeric plant [2(A2-194 x D8)] as pollen donor, to begin transferring the
resistance from wild diploid cotton species to cultivated tetraploid cotton.
Speaker Information: Carlos Avila, Univ. of Arkansas, 123 Plant Science Building University of Arkansas, Fayetteville, AR 72701; Phone: (479) 575-6807; E-mail: