Confirmation of Gossypium hirsutum Chromosome Substitution Lines using SSR markers

Germplasm and Genetic Stocks

poster

Saha, Sukumar; Stelly, David

Saha, Sukumar

Saha, Sukumar

Confirmation of Gossypium hirsutum Chromosome Substitution Lines using SSR markers S. Saha1, D. M. Stelly2, D. Raska2, A. Hulse2, O. A. Gutiérrez1,3, A. Makamov4, V. Gotmare5, F. Wang2, Sh. Manchali2, D. Deng1, J. N. Jenkins1, I. Salakhutdinov, M. Ayubov and I. Y. Abdurakhmonov4 1USDA-ARS, Crop Science Research Lab., Mississippi State, MS 39762 USA, 2Texas A&M University, College Station, TX 77843 USA, 3Current Address USDA-ARS, Subtropical Horticultural Research Station, Miami, FL, 33158 USA, 4Center of Genomic Technologies, Institute of Genetics and Plant Experimental Biology, Academy of Sciences of Uzbekistan. Yuqori Yuz, Qibray Region Tashkent District, 111226 Uzbekistan, 5Division of Crop Improvement, Central Institute for Cotton Research, Post Bag No. 2, Shankarnagar PO, Nagpur , India ABSTRACT Two major impediments in the genetic improvement of cotton are: 1) under-utilization of diverse germplasm and 2) insufficient information about genes that control important traits. The primary gene pool for cotton includes wild types of G. hirsutum L., as well as the other four 2n=52 species of Gossypium (G. barbadense, G. mustellinum, G. tomentosum and G. darwinii) all of which are readily hybridized and contain AD1 genomes (G. hirsutum L.) and thus share a common gross chromosome structure. Nonetheless, previous interspecific introgression efforts using conventional breeding methods have had very limited success, indicating deep-seated genetic conflicts in the hybrids preclude facile recovery of agronomically useful types. To help overcome these barriers, we are developing alien chromosome substitution (CS) lines from G. barbadense, G. mustellinum and G. tomentosum. The development of each CS line involves four stages: (i) create isogenic Upland chromosome-deficient stocks, by backcrossing various chromosome deficiencies (monosome or telosome) to a common line, namely ‘Texas Marker-1’ (TM-1); (ii) create a F1 substitution stock that is monosomic or monotelodisomic (i.e., partially hemizygous) by recurrent backcrossing to each isogenic cytogenetic stock as a recurrent seed parent; (iii) inbreed the backcrossed hypoaneuploid derivative to recover a euploid disomic substitution line; (iv) confirm the cytogenetic and genetic constitution of the disomic lines by cytological analysis and chromosome-specific SSR markers. We have developed several CS lines from G. barbadense, G. mustellinum and G. tomentosum respectively based on cytological analysis. These substitution lines are nearly isogenic to the common parent TM-1 for 25 chromosome pairs, as well as to each other, for 24 chromosome pairs. At the time development was initiated for some CS lines, molecular markers did not exist, and by the time several lines were released, very few accurately mapped chromosome specific SSR markers were available in the public domain. Recently in addition to the cytological analysis, we have been using SSR markers from one or more linkage maps to assess the constitution and genetic identity of the CS lines. The overall objective of this paper is to report on the genetic identity of the CS lines using SSR markers. For CS euploid lines (2n=52), we compared marker profiles of CS lines, parents and other CS germplasm. For most CS lines and most mapped markers, the observed SSR profiles were concordant with expectations. For a minority of markers and lines, however, the results were discordant; these markers, linkage groups, and CS lines are being further investigated to better define these research and breeding resources.