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United States Department of Agriculture

Agricultural Research Service

Research Project: Development of Soybean Lines with Improved Toerance to Heat and Drought

Location: Crop Genetics Research Unit

2013 Annual Report

1a.Objectives (from AD-416):
Combine water use efficiency, pollen viability, and high germinability into improved high-yielding soybean lines and determine the genetic mechanism for high germinability.

1b.Approach (from AD-416):
Conventional plant breeding, marker identification and mapping.

3.Progress Report:

Drought and heat are important yield constraints in the midsouthern U.S. for soybean production. Drought and heat are expected to increase in the future. Hence, an objective of this research is the development of soybean lines with improved tolerance to heat and drought. An important part in the development of new stress-tolerant soybean lines is understanding how heat and drought tolerance are inherited. Hence, soybean families need to be developed to study inheritance as well as to select for improved tolerance. In terms of family development for genetic studies, seeds from 60 F5-derived F7 recombinant inbred lines (RIL) from PI 587982A x S99-11986 arrived from Puerto Rico and were planted in Stoneville, MS, May 30, 2013. Seed for each RIL will be increased and preliminary tests for seed assays will be conducted on harvested seed. As a backup, F2 seeds of a population of an improved high-germinability parent with a poor seed quality parent (04025-1-1-4-1-1 x DT97-4290) arrived from Puerto Rico and were planted in Stoneville, MS, May 30, 2013. Two independent populations of 300 and 240 F2 seeds were planted of the above cross. Individual plants from each population will be tagged for identification and tissue sampling. The best population will be advanced for RIL development and future genetic analysis.

Tolerance to drought can be measured in terms of a soybean plant’s water use efficiency (WUE). Combining improved WUE with high-germinability under heat stress in a new soybean line would be very desirable. Toward that end, 766 F2 plants from 6 independent populations of PI 567201D x 04025-1-1-1-4 were grown in 2012. From the total of 766 plants, 57 agronomically improved plants were selected and harvested. Seeds from these 57 plants were sent for standard germination tests. Based on these germination tests, nine F2:3 families were selected for testing for WUE. The nine families were planted in Stoneville, MS, April 29, 2013. Each emerged plant was tagged for later tissue sampling for WUE in 2013. Leaf tissues from 2012 of these nine lines and the parents are currently being ground and prepared for shipping to the University of California, Davis Stable Isotope Facility. Lines with the best WUE scores will be selected prior to tissue sampling in 2013 so that only individual plants from selected F2:3 families will be tissue sampled in 2013. This process will be repeated over the next three to four years to create a new pure line soybean with high WUE and high germinability.

Additional breeding populations have been developed to combine WUE with high germinability. The following F2 seeds arrived from Puerto Rico and were planted in Stoneville, MS, May 30, 2013: PI 567201D x 04025-1-1-4-1-1 (Two populations of 160 seeds each) 04025-1-1-4-1-1 x PI 567201D (One population of 320 seeds) PI 398965 x 04025-1-1-4-1-1 (Five populations of 80 seeds each) 04025-1-1-4-1-1 x PI 398965 (Four populations of 80 seeds each)

The ability of soybeans to fix nitrogen during drought stress is also important for high seed yield. Hence, the following populations were developed to combine high germinability and high nitrogen fixation: PI 574483 x 04025-1-1-4-1-1 (Four populations of 80 seeds each) PI 442012A x 04025-1-1-4-1-1 (Three populations of 80 seeds each)

Finally, total plant nitrogen is associated with plant productivity. Therefore, the following populations were created to combine high nitrogen concentration with high germinability: PI 567572B x 04025-1-1-4-1-1 (Four populations of 80 seeds each) PI 417107 x 04025-1-1-4-1-1 (Three populations of 160 seeds each)

These breeding populations will be selected first for improved plant type and then high germinability. Selected families with high germinability will then be assayed for WUE, nitrogen fixation, and nitrogen concentration as appropriate.

Last Modified: 7/24/2014
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