Crop Biotechnology
Year:2011 | Volume:1 | Issue:1|Papers Count:8

Rice is currently the main staple food for more than 2 billion people in Asia, Africa and Latin America. It is also an excellent model cereal for molecular biology and genetics research. Salinity is a major factor limiting rice production worldwide. The analysis of stress-responsiveness in plants is an important route to the discovery of genes conferring stress tolerance which could be then uses in breeding programs. To further understand the mechanism of plant response to salinity, we employed a proteomic approach to profile the protein changes of the third leaf of rice and root under salt stress. Plants were grown in Yoshida nutrient solution and salt was stress imposed after 25 days. Plants were treated by 100 mM NaCl for10 Days. After that, third leaves and total root were collected from the control and salt stressed plants. The Na+ and K+ content of the leaves/roots and several yield components changed significantly in response to short-term salt stress and their proteome patterns were analyzed using 2-DE in triplicates. The expression pattern of proteins changed in all the leaves/roots in response to stress considerably. More than 488 and 345 proteins were detected repeatedly in the 2D gels for root and leaf, respectively. 107 proteins in the root and 86 proteins in the leaf of two genotypes showed significant response to stress. Three proteins in leaf gels and 2 proteins in root gels were selected and identified by ESI-Q-TOF. The most important ones included ferritin, rubisco activase and ascorbat peroxidase in leaf and peroxidase and ascorbat peroxidase in root. All of those were enzymes and involved in detoxification and removal of reactive oxygen species (peroxidase, ascorbat peroxidase), iron homeostasis (ferritin) or were involved in the activation of other enzymes (rubisco activase).

The objective of this study was to achieve improved induction of embryogenesis in bread wheat microspores. Some F1 hybrids i.e M85-6×90, M85-8×90, mv17×shiroudi, mv17×kavir and kavir×bam were used. Microspores were cultured in A2 medium containing different amounts of maltose (60 & 90 g/lit) depending on the genotype used. Analysis of variance for embryogenesis and regenerable embryos showed a highly significant difference between hybrids but there was no significant difference between the media (A2-60 & A2-90) and no interaction effects. M85-6×90, mv17×Shiroudi and mv17×kavir produced the highest ratio of embryogenesis among the hybrids. In the regeneration phase, mv17×Shiroudi and M85-6×90 had the highest frequency of regenerable embryos. The effect of 2,4-D as a novel inducer of microspores embryogenesis in Falat was investigated. Falat is known as the most responsive wheat cultivar to microspore culture technology,. Microspores were subjected to 2,4-D at 3 different concentrations of 15, 25, 35 mg/l for 30 minutes while microspores without any stress treatment were used as the control. The embryogenesis of microspores stressed with 2,4-D were better than that of the control. The highest embryogenesis yield was achieved at 15 mg/l 2,4-D. The most regenerated embryos were obtained at 2,4-D concentrations of 15 and 25 mg/l. According to the results obtained, 2,4-D is introduced as a new embryogenesis inducer in microspores of wheat.

Protein phosphatase 2C family consists of a group of evolutionary-conserved serine/threonine phosphatases which play a role in stress signal transduction. A subfamily of this protein phosphatases in Arabidopsis, including ABI1 and ABI2, are known as components of Abscisic acid signal transduction pathway. Their mutants are hypersensitive to ABA showing an increased expression during seed dormancy and adaptive responses to drought. Considering sensitivity of rice to abiotic stresses, particularly drought, identification of this gene family in rice and studying their role in response to stress would be beneficial. In this research, nine OsPP2C proteins (OsPP2C1 to OsPP2C9), carrying all the conserved motifs of this subfamily were found in rice, Among them, only OsPP2C5 transcript levels were significantly up-regulated by drought and abscisic acid which is down-regulated by re-watering or ABA removal. Drought stress induced OsPP2C5 gene expression in all the studied tissues. Based on the RNA in situ hybridization experiments, OsPP2C5 transcripts were observed in almost all cells and accumulated more in the nuclei in divisional zone of the drought stressed peduncles. However, the transcripts of this gene were accumulated at higher levels in the primary and secondary vascular bundles, phloem and xylem parenchyma, epidermal cells and sclerenchyma/ chlorenchyma precursors. Based on the achieved results, the OsPP2C5 gene seems to play a role in ABA/ drought stress signal transduction. It is expected that appropriate genetic manipulations of this gene family would increase rice tolerance to abiotic stresses.

A system was designed using E. coli heat shock promoter (groE) in plastid vector and a hybrid plant/bacteria sigma factor was constructed under control of a tissue specific promoter. This system was designed for overcome to deleterious effects on plant growth and fertility that may be caused by transgene overexpression. So that hybrid sigma factors contained N-terminal motives of tobacco sigma factors including chloroplast signal peptide and RNA polymerase interaction domains, composed by C-terminal motif of E. coli sigma32 that able to recognition and binding to groE promoter. Then this gene, HSig, was cloned in Agrobacterium vector after adding regulatory elements. The result vector was used for transformation of an Iranian variety of tobacco. Detection of transgenic plants was performed by PCR, southern blot and RT-PCR analysis. The Hsig gene expression and its targeting to plastid was confirmed after transformation of tobacco chloroplast using gene gun technique for targeting of green florescent protein (GFP) under control of groE promoter usingpFNGi vector into transgenic HSig explants. We hope that the system that was designed and constructed in this study for GFP expression in chloroplast genome, be able to apply in molecular farmingfor expression of any other desired genes instead of GFPfor specific gene expression in chloroplast.

This research was conducted to validate and fine-map the region attributed to salinity tolerance (Saltol) on chromosome1 in rice at International Rice Research Institute (IRRI) during years 2005 to 2007. A major effect QTL (Saltol) which is responsible for Na+ and K+ uptake and Na/K ratio was identified using F8 recombinant inbred lines (RILs) of Pokkali/ IR29 cross on chromosome 1. This QTL explained around 64.3 to 80.2% of the phenotypic variation for the mentioned traits. Fine-mapping was done using 10 SSR and EST-SSR markers and near isogenic lines (BC3F4), derived from IR29 × Pokkali produced for salinity tolerance at seedling stage. Random BC3F4 individuals were genotyped and phenotyped under two different electrical conductivities at seedling stage. QTL responsible for salinity tolerance at both ECs, were found in the Saltol region, which explained 18 and 24% of the phenotypic variation for SES scores, respectively. According to the present results, possible location of Saltol was found in the interval around 1.2 cM on chromosome 1 that was around 350Kb based on physical map. This QTL was mapped at the intervals of RM8094, RM3412 and CP6224. Therefore, molecular breeding for salinity tolerance in Iranian genotypes could be done using the mentioned markers.

Commonly, plant roots colonized by arbuscular mycorrhizal fungi (AMF) can tolerate different stresses such as soil salinity. Thereby, identification of the dominant AMF species in the saline soils and their application as biofertilizer could be very useful in order to increase crop productivity under such conditions. For this purpose, sampling was performed from root and rhizosphere of wheat, barley and weeds in Yazd, East Azerbaijan, Qom and Markazi provinces of Iran. The spore morphological properties of the isolated AMFs were studied. Then, samples were screened using a two-step nested PCR methodology. At the first step, AMF-specific primers, including LSU-Glom1 and SSU- Glom1 were used, followed by Alu1 digestion of the PCR products, and then at the second step, the digested PCR products were amplified by using fungal universal primers (ITS4 and ITS5) in order to amplify the ITS-rDNA region. The PCR products were then cloned, and digested by Taq1. The results of the morphological characteristics and sequence analyses showed that two AMF genus, including Glomus (more than 90%) and Acaulospora (10%) were dominant. The species G. mosseae (50%), G. intraradices, G. sinosum, G. constrictum, G. etunicatum, G. versiforme, G. fulvom, and Glomus sp were identified using the molecular analysis. The maximum species diversity was observed in the fields located in Yazd Province and in rhizosphere of wheat. Overall, the results of the present study showed that the species G. mosseae had the highest dominancy and adaptivity under saline conditions. Hence, this species can be used as a source of biofertilizer in such regions after performing complementary experiments.

Some different sources of cytoplasmic male sterility (CMS) have been described in beets. Up to now, hybrid seed production in the sugar beet has exclusively relied on Owen CMS. Discovery of Owen CMS in a sugar beet cultivar has played an important role in the development of hybrid cultivars and changed breeding methods in sugar beet. Hybrid plant cultivars carrying CMS Owen are semi fertile. The aims of this research were to evaluate cytoplasm variation and to determine cytoplasmic male sterility source used in production of new cultivars. Mitochondrial minisatellites and CAPS marker were used. Banding profiles of four cultivars and two male sterile and fertile lines demonstrated the presence of Owen CMS in breeding procedures of these cultivars. Cytoplasmic variation was not observed between cultivars, but more than half of progeny derived by crossing a cultivar plants with SHR01-P12 pollinator plants was sterile. It seems, other nucleus gene (s) besides Owen CMS have been used in producing some new hybrid cultivars.

Fourteen populations of sections Hymenobrychis, Lophobrychis and Onobrychis of sainfoin were collected from natural habitats across Iran. Number and size of the chromosomes as well as karyotypic formula of the populations were measured and studied using their root tip meristemes. The basic chromosome number varied between x=7 and x=8 and their chromosomal types were metacentric and sub-metacentric. As for the genome length average, the highest belonged to O. viciaefolia (48.157.m) and the lowest to O. amoana subsp. meshhedensis (14.409.m). The results of variance analysis based on unbalanced completely randomized design showed significant differences among the populations for the most of the studied traits (P<%1). O. michauxii 2 classified as asymmetric class of B and others as A. O. amoena subsp. meshhedensis with 14m formula, stand in A class, had the most relative length of shortest chromosome (68.26), lowest intra chromosal asymmetrical (0.12), lowest differences of relative length (5.31), and the highest total form percentage was symmetrical species. Using principal components analysis, the first two components justified %97.94 of the total variance. By cutting dendrogram, resulted from cluster analysis based on the karyotypic parameters species, the highest distance was obtained between O. schahuensis 1 and O. viciaefolia and the lowest metric distance value was obtained between populations of O. schahuensis 1 and O. chorassanica 1.