Chromium accumulation and tolerance in selected plant species /
This research was aimed at assessing tolerance and accumulation of Cr by various crop species, and understanding the related mechanisms. In a Cr-screening study comparing related growth, dry weight and survival rates of ten candidate crop species in test-tube nutrient-culture, soybean and sunflower...
| Main Author: | |
|---|---|
| Format: | Thesis Book |
| Language: | English |
| Published: |
[Place of publication not identified] :
[publisher not identified] ;
1999.
|
| Subjects: | |
| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=731685961&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | This research was aimed at assessing tolerance and accumulation of Cr by various crop species, and understanding the related mechanisms. In a Cr-screening study comparing related growth, dry weight and survival rates of ten candidate crop species in test-tube nutrient-culture, soybean and sunflower were found to be the most promising Cr-tolerant species. In hydroponic experiments, soybean was more tolerant than sunflower with both Cr(III) (Cr[]) and Cr(VI) {(Cr[]O[])[]}. Soybean appears to respond to stress from the two Cr forms with different mechanisms, utilizing absorption-tolerance with Cr(III) and exclusion with Cr(VI). Soybean stem anthocyanin accumulation was enhanced by 0.1 mM Cr(VI) treatment. Also, northern blot analysis showed that gene GmGST26-A was induced by both Cr(III) and Cr(VI) treatments, but not in the control. It appears that there were two versions of transcripts overlapping each other with a size difference of 0.4 kb. This phenomenon ray have been caused by splicing-inhibition of the only intros and related to the production of a truncated version of protein, which, coupled with anthocyanin accumulation, may have been responsible for Cr-phytochelatin complexes targeting into and sequestering inside the vacuole. With soybean plants without Cr treatments, colonization with the mycorrhizal fungi Glomus intraradices (Schenck & Smith) enhanced plant growth, dry mass accumulation, net photosynthesis (A), and stomatal conductance (g[]). It also enhanced essential elements uptake including N, P, K, Mg, Cu, B, Zn and Mo. Since mycorrhizae alleviated Cr toxicity and enhanced growth and net-photosynthesis, mycorrhizae-treated plants grew to a larger size and accumulated more Cr per plant. Thus, VAM is promising in repudiation of Cr(VI) contamination. Whereas, with high Cr(III) treatment (12 mM), VAM had no substantial colonization in roots, thus mycorrhizal ejects were insignificant. Both VAM and non-VAM soybean plants accumulated substantial amounts of Cr in plant tissues, especially in roots when exposed to high concentrations of Cr(III), thus soybean is very promising for repudiation of Cr(III) contamination. Experimental results showed that deliberate low P supply led to higher extraction of Cr(VI) from the soil. In the meantime, colonization of VAM enhanced P uptake and compensated for the low input. |
|---|---|
| Item Description: | Vita. "Major Subject: Plant Physiology". |
| Physical Description: | xii, 101 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilm Inc. |
| Bibliography: | Includes bibliographical references (leaves 89-99). |