انجام کلیه امور مشاوره ای واجرایی در زمینه ی کشاورزی وعلوم زیستی

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THE ROLE OF DREB2 GENE IN DROUGHT TOLERANCE OF COMMON WHEAT (TRITICUM AESTIVUM L.) ASSOCIATED WITH AZOSPIRILLUM BRASILENSE

THE ROLE OF DREB2 GENE IN DROUGHT TOLERANCE OF COMMON WHEAT (TRITICUM AESTIVUM L.) ASSOCIATED WITH AZOSPIRILLUM BRASILENSE

 

Abstract

Dehydration causes loss of wheat (Triticum aestivum L.) yield. Inoculation of wheat with
Azospirillum brasilense improves its tolerance to drought. Although up-regulation of DREB2 gene has
increased drought tolerance of wheat, less information exists about DREB2 expression under inoculation
with A. brasilense. In this study, the physiological responses of different pairs of six wheat cultivars with
A. brasilense Sp7 and Sp245 strains were evaluated to drought and the tolerant (Roshan-Sp245), sensitive
(Shahpasand-Sp7), moderately tolerant (Roshan-Sp7) and moderately sensitive pairs (Shahpasand-Sp245)
were selected. Afterward, in the second experiment, DREB2 expression of the selected pairs was
evaluated under inoculation and/or dehydration (ψ w = -90 MPa) at 0, 120 and 360 minutes. At 120 min,
DREB2 expression was more in the tolerant and moderately tolerant pairs than others and also higher in
inoculated and/or dehydration conditions. Root’s DREB2 was up-regulated almost 700-fold in the tolerant
and moderately tolerant pairs under dehydration. In contrast, in the sensitive cv., DREB2 expression did
not change due to dehydration or inoculation. This could be the effect of compatibility or homology of
A. brasilense strains and wheat cultivars which affected DREB2 expression. Therefore, DREB2
expression had a significant effect on increased drought tolerance in tolerant and moderately tolerant
pairs.
Keywords: wheat, Azospirillum brasilense, Sp7, Sp245, drought tolerance, DREB2 gene, dehydration

 

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THE EFFECT OF PHYSICO-CHEMICAL VARIATIONS ON PHYTOPLANKTON STATUS IN THE MARGIN OF CHOGHAKHOR WETLAND, IRAN

Abstract. Many human activities in the margin of Choghakhor wetland, (Iran) causes evaluation of the
phytoplankton status in relation to the physico-chemical parameters in different seasons of 2011 in 5
marginal stations of the wetland. Water samples prepared in triplicate and temperature, pH, dissolved
oxygen, nitrate and phosphate concentration were measured using APHA methods. The phytoplankton
identified, counted and Shannon diversity index (Hʹ). Phytoplankton community included 59 genera, 43
families and 6 divisions, among which Bacillariophyta was the most common (46.6%) followed by
Chlorophyta (32.0%), Cyanophyta (13.3%), Dinophyta (4.4%), Euglenophyta (3.0%) and Chrysophyta
(0.8%). Phytoplankton density, nitrate, and phosphate concentration were different in different stations
and seasons (P < 0.05). The highest density was recorded for Nitzschia followed by Cosmarium,
Microcystis, Peridinium, Euglenaria and Dinobryon. Also, Microcystis density was maximum in station 5
[S5]. There were significant correlations between the phytoplankton density and nitrate concentration
(r = 0.6, P < 0.01), Chlorophyta and phosphate concentration (r = 0.3, P < 0.01), Cyanophyta and
phosphate concentration (r = 0.2, P < 0.05). Although wetland water was still clean (Hʹ > 3), high density
of Nitzschia and Microcystis as eutrophication bio-indicators showed starting of eutrophication.
Microcystis as the most abundant genus of Cyanophyta must be seriously controlled to avoid blooms in
the wetland.
Keywords: phytoplankton composition, physico-chemical parameters, Choghakhor wetland, nitrate,
phosphate

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