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United States Department of Agriculture

Agricultural Research Service

Research Project: ENHANCING QUALITY, UTILITY, SUSTAINABILITY, ENVIRONMENTAL IMPACT OF COTTON AND ITS BYPRODUCTS THROUGH IMPROVEMENT IN HARVEST/GIN PROCESSING

Location: Cotton Ginning Research

Title: Genetic variation in salt tolerance at the seedling stage in an interspecific backcross inbred line population of cultivated tetraploid cotton

Authors
item Tiwari, Rashmi -
item Picchioni, Geno -
item Steiner, Robert -
item Jones, Don -
item Hughs, Sidney
item Zhang, Jinfa -

Submitted to: Euphytica
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 12, 2013
Publication Date: May 3, 2013
Citation: Tiwari, R.S., Picchioni, G., Steiner, R.L., Jones, D.C., Hughs, S.E., Zhang, J. 2013. Genetic variation in salt tolerance at the seedling stage in an interspecific backcross inbred line population of cultivated tetraploid cotton. Euphytica. 194(1):1-11.

Interpretive Summary: Increasing soil salinity or salt buildup in agricultural soils, particularly in the irrigated southwestern United States, reduces cotton productivity and is a serious problem for long term cotton production. Classical breeding techniques were used to obtain a hybrid cross between Upland cotton (Gossypium hirsutum) and Pima cotton (G. barbadense) which was then backcrossed using Upland as the recurrent parent and then self pollinated over several generations to obtain 142 test lines. The objectives of this study were then to assess the genetic variation of cotton seedling salt tolerance and identify salt tolerant strains within these 142 test lines. Seedling growth salt test condition was 200 mM NaCl that was compared to non-saline control conditions. All seedlings under salt stress showed significant reduction in all plant growth characteristics compared to the control as expected. However, there were significant differences within the test lines for most growth traits. The results indicate that several of the test lines had higher seedling salt tolerance than either the Upland or Pima parents which were not salt tolerant at the seedling growth stage. The results also indicate that salt tolerance during cotton seedling growth is moderately inherited and environmental variation plays an equally important role. The overall results demonstrate that classical breeding techniques of backcrossing followed by repeated self-pollination is a successful strategy to enhance salt tolerance at the seedling stage by transferring genetic factors from Pima to Upland cotton.

Technical Abstract: Soil salinity reduces cotton growth, yield, and fiber quality and has become a serious problem in the arid southwestern region of the Unites States. Development and planting of salt-tolerant cultivars could ameliorate the deleterious effects. The objectives of this study were to assess the genetic variation of salt tolerance and identify salt tolerant genotypes in a backcross inbred line (BIL) population at the seedling growth stage under 200 mM NaCl and non-saline (control) conditions. The BIL population of 142 lines was derived from an interspecific cross between Upland cotton (Gossypium hirsutum) cv. SG 747 and Pima cotton (G. barbadense) cv. Pima S-7, followed by two generations of backcrossing using SG 747 as the recurrent parent and three generations of selfing. As compared with the non-saline conditions, seedlings under the salinity stress showed a significant reduction in all the plant growth characteristics measured, as expected. Even though the Pima parent was somewhat more sensitive to salt than the Upland parent at the seedling growth stage, the salt response as measured by percent reduction did not show any significant difference. However, there were significant effects of genotype for all traits except for leaf number, treatment for all the traits, and genotype x treatment interaction for only plant height. The results indicate that transgressive segregation occurred during the process of backcrossing and selfing even though both parents were not salt tolerant. Based on percent reduction of the traits measured, several BILs performed better than both parents, indicative of higher salt tolerance at the seedling growth stage. Coefficients of correlation between all the traits were significantly positive, indicating an association between the traits measured. The estimates of broad-sense heritability were 0.69, 0.46, 0.47, 0.43, and 0.49 for plant height, fresh weight of shoot and root, and dry weight of shoot and root, respectively. The results also indicate that salt tolerance during cotton seedling growth is moderately inherited and environmental variation plays an equally important role. The overall results demonstrate that backcrossing followed by repeated self-pollination is a successful strategy to enhance salt tolerance at the seedling stage by transferring genetic factors from Pima to Upland cotton.

Last Modified: 7/14/2014
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