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Impact of Drought and Aflatoxin Production on the Phytochemical Content of Different Peanut (Arachis hypogaea L.) Genotypes
Başlık:
Impact of Drought and Aflatoxin Production on the Phytochemical Content of Different Peanut (Arachis hypogaea L.) Genotypes
Yazar:
Nayak, Jwalit J., author.
ISBN:
9780438009837
Yazar Ek Girişi:
Fiziksel Tanımlama:
1 electronic resource (89 pages)
Genel Not:
Source: Masters Abstracts International, Volume: 57-06M(E).
Advisors: Mehboob B. Sheikh Committee members: Odemari S. Mbuya; Islam El Sharkawy.
Özet:
Drought stress predisposes peanut to Aspergillus invasion leading to aflatoxin contamination. Plants produce phytoalexins when exposed to certain biotic and abiotic stresses to withstand the stresses and prevent pathogen invasion. They are found in all parts of peanut plants, except in stems, therefore every part of the plant excluding stem is a source of stilbene. Phytoalexins (Stilbenes) are natural compounds occurring in several plant families, of which Peanut (Arachis hypogaea L.) is one of them. Resveratrol is the main phytoalexin that is expressed under stress and protects plant from pathogen infection. However, under drought conditions peanut plant loses its ability to produce phytoalexins and become susceptible to Aspergillus invasion and aflatoxin contamination. The drought tolerant genotypes have been shown to continue to produce phytoalexins under moderate stresses and resist pathogen invasion and aflatoxin production.
This study was intended to determine the relationship between stilbene producing ability of a genotypes and Aspergillus invasion to define the possibility of using this characteristic for germplasm evaluation to identify drought and aflatoxin tolerant genotypes for use in developing drought/aflatoxin tolerant genotypes.
Initially the mature seed of peanut cultivar, Georgia Green (GG) were used to develop and optimize postharvest stilbene induction technique. The stilbene content and composition of stilbene induced seed was confirmed by HPLC analysis. The stilbene data showed that subsequent incubation of seed for four days produced maximum amount of stilbenes. Subsequently all available peanut genotypes were evaluated for their stilbene producing ability to determine genetic variation in stilbene producing ability among peanut genotypes. Based on the resulting stilbene data peanut genotypes were grouped into high and low-stilbenes producing varieties. The results showed that peanut cultivars DRT40, DRT43, K1504, K1622, and Kadiri-7 produced highest amount of stilbenes while cultivars K1620, K1814, Narayani, K1632 and Tirupati-3 produced relatively lower amount of stilbenes.
To correlate stilbene-producing ability of peanut genotypes with their drought tolerance level the above 10 varieties were grown in pot culture and maintained in the greenhouse. The 50 days old peanut plants were exposed to water stress by withholding water while control plants were irrigated normally. The effect of water stress on plant performance was monitored till week 7 after imposition of water stress, by monitoring changes in morphological characteristics of plant such as height, leaf size, number of branches, number of leaves and internode length were recorded. The collected data was analyzed using SAS software 9.4. The results showed that at 2 day of stress no significant differences were observed in plant height among the varieties. Tirupati-3 and K1814 had higher mean compared to K1622 for number of leaves and branches, while for leaf size, the former had higher means than K1632, respectively. On 4 th day of stress, no significant difference was observed for plant height and number of leaves. Narayani, Tirupati-3 and K1814 performed significantly better than K1622 and DRT40 for number of branches. For leaf size, K1814 and K1622 was better than K1632. K1620 and Kadiri-7 had higher means for internode length than K1814 and DRT43. On 6th day of stress, Narayani, Tirupati-3 and K1814 showed higher means compared to DRT40 and K1622. Narayani also had higher means than K1504 for leaf size, but K1504 had higher means for internode length compared to DRT43 and K1814.
In addition to morphological characteristics the water stressed plants were also subjected to metabolite analysis. Leaves were collected from control and water stressed plants and analyzed for total sugars and total free amino acids content. The results showed that total leaf sugars and free amino acids content of cvs. DRT40, DRT43 and K1622 increased with increasing duration of stress while they decreased in cv. K1632.
Stilbenes are phytoalexins and are expressed by plant in response to certain biotic and abiotic stresses to prevent/resist stresses. However, under drought stress conditions plants lose their ability to produce stilbenes and become susceptible to pathogen invasion. Plants that continue to produce stilbenes under stress will be able to resist pathogen invasion compared to those that fail to produce these components. To determine interrelationship between stilbene producing ability of seed and Aspergillus invasion we have challenged peanut seed by inoculating them with Aspergillus spores after in vitro stilbene induction. These studies showed major differences in fungal colonization of seed between the control (without stilbene induction) seeds and stilbenes-induced seeds. Of the 10 varieties tested seed of cultivars K1504, K1620 and K1632 showed limited mycelial development on seed following Aspergillus inoculation compared to control (without stilbene induction), while the seed of other varieties showed no fungal growth. Interestingly the cultivars with no fungal growth also expressed significantly large amount of stilbenes compared to other varieties which expressed relatively lower amount of stilbenes. These data suggested that the cultivars expressing higher amount of stilbenes completely prevented fungal colonization while the varieties expressing lower amount of stilbenes sustained limited fungal development on seed.
Notlar:
School code: 0872
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Yer Numarası | Demirbaş Numarası | Shelf Location | Lokasyon / Statüsü / İade Tarihi |
---|---|---|---|
XX(694429.1) | 694429-1001 | Proquest E-Tez Koleksiyonu | Arıyor... |
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