Project Summaries

12-192  Project Manager: D. C. Jones

INCREASING DESCRIPTOR DATA AVAILABLE FOR COTTON GERMPLASM AND OBSOLETE LINES

Jodi A. Scheffler, USDA-ARS

Our objective was to collect phenotypic data using a standardized descriptor format and an electronic data recorder on material from the Cotton Germplasm Collection and add data to the new database CottonGen.

Approximately 1,900 accessions were sent to the 2011-2012 Cotton Winter Nursery (CWN). The PI and ARS Curators for the Cotton Germplasm Collection (CGC, College Station TX) traveled to the CWN in February and collected field descriptor data and made digital images of the accessions. The accessions were harvested and 1,000 of them sent back to Stoneville. The samples are currently being processed. The seed and fiber will be sent to College Station for further testing and storage. This project supports another Cotton Incorporated project 12-178 and their annual report by PI James Frelichowski provides additional details.  Monica Sheehan is also developing a booklet with digital images to illustrate the scores for the descriptors.

A second objective was to survey the variation present in elite cotton lines for the terpenoid aldehydes (TA) gossypol, hemigossypolone and heliocides and evaluate the effect of different environments on TA levels.  Based on results from core project 09-540, it was determined that the percent gossypol in seed was not a good indicator of gossypol content in the rest of the plant and the amount of insect damage was more closely correlated with the amount of other related terpenoid aldehydes (TA) like hemigossypolone (HGQ) and heliocides. It was also observed that the amount of these other TAs was not highly correlated with seed gossypol, and it was possible to have lower seed gossypol and still have high leaf TAs. There have been studies proposing that other compounds besides gossypol could protect the plant, but previously there was no inexpensive and sufficiently accurate way to measure the different compounds. Starting with an HPLC assay developed by Dr. Bob Stipanovic (ARS College Station, TX), we modified it for screening large numbers of samples and can routinely separate and quantify gossypol, HGQ and total heliocides. We have analyzed roots, petals, stigmas, stems, cotyledons, boll hulls and leaves. Leaves appear to be a good estimator of the plant's TA level.

Previous tests conducted as part of CI projects 08-399 and 09-540, where plots were challenged with insects, had higher levels of TAs than the non-infested plots (Scheffler et al. Agricultural Sciences 2012). At Starkville, Dr. Jack McCarty had two tests, one he infested with "worms" (tobacco budworm, Heliothis virescens) and a second which was not infested. The "Worm" plot was sampled June 29 (pre-flower) before any worms were applied, and then again July 27 after the plots had been infested weekly with worms. On July 27th, leaves were also sampled from an identical test (Yield Control) that had not been infested with worms and had been sprayed routinely with insecticides. The other five locations were only sampled at mid-flower. The tests were all organized in a randomized complete block design, and two replications were sampled at each location. Ten 2 cm terminal leaves (one leaf per plant from 10 plants) were collected per plot. The leaves were approximately the size of a quarter. The samples were collected in a 50 ml centrifuge tube, stored on ice and then freeze-dried, ground and analyzed. The leaves were analyzed for gossypol, HGQ and total heliocides. These results will be compared with the yield and fiber data collected by the RBTN cooperators.

Preliminary results from the Starkville "Worm' and "non-Worm" tests highlighted what had been observed previously. Pre-flower TA levels were generally greater than those observed at mid-flower. Gossypol was present in the lowest concentration followed by total heliocides then HGQ with significantly higher levels.

At mid-flower, the plots infested with tobacco budworm showed higher levels of gossypol and HGQ compared to the non-infested plots, but the total amount was lower than at pre-flower before infestation. The heliocides did not respond consistently to the worm infestation and in some cases the levels were higher in the non-infested plots. This is interesting, as the heliocides were originally identified as compounds effective against cotton bollworm and tobacco budworm. This will be investigated further.

The two other locations reported here, Keiser, AR and Stoneville, MS, were sampled at mid-flower. The levels at Stoneville were similar to those at in the non-infested test at Starkville, while Keiser had consistently higher levels. Over locations several entries were consistently higher than the others. The remaining locations have been analyzed and are currently being summarized. This data will be combined with the yield and fiber data and analyzed.

 

Project Year: 2012
 

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