Characterization of ASR gene and its role in drought tolerance in chickpea (Cicer arietinum L.)

Chickpea has a profound nutritional and economic value in vegetarian society. Continuous decline in chickpea productivity is attributed to insufficient genetic variability and different environmental stresses. Chickpea like several other legumes is highly susceptible to terminal drought stress. Multiple genes control drought tolerance and ASR gene plays a key role in regulating different plant stresses. The present study describes the molecular characterization and functional role of Abscissic acid and stress ripening (ASR) gene from chickpea (Cicer arietinum) and the gene sequence identified was submitted to NCBI Genbank (MK937569). Molecular analysis using MUSCLE software proved that the ASR nucleotide sequences in different legumes show variations at various positions though ASR genes are conserved in chickpea with only few variations. Sequence similarity of ASR gene to chickpea putative ABA/WDS induced protein mRNA clearly indicated its potential involvement in drought tolerance. Physiological screening and qRT-PCR results demonstrated increased ASR gene expression under drought stress possibly enabled genotypes to perform better under stress. Conserved domain search, protein structure analysis, prediction and validation, network analysis using Phyre2, Swiss-PDB viewer, ProSA and STRING analysis established the role of hypothetical ASR protein NP_001351739.1 in mediating drought responses. NP_001351739.1 might have enhanced the ASR gene activity as a transcription factor regulating drought stress tolerance in chickpea. This study could be useful in identification of new ASR genes that play a major role in drought tolerance and also develop functional markers for chickpea improvement

Evolutionary potential and adaptation of Banksia attenuata (Proteaceae) to climate and fire regime in southwestern Australia, a global biodiversity hotspot

Substantial climate changes are evident across Australia, with declining rainfall and rising temperature in conjunction with frequent fires. Considerable species loss and range contractions have been predicted; however, our understanding of how genetic variation may promote adaptation in response to climate change remains uncertain. Here we characterized candidate genes associated with rainfall gradients, temperatures, and fire intervals through environmental association analysis. We found that overall population adaptive genetic variation was significantly affected by shortened fire intervals, whereas declining rainfall and rising temperature did not have a detectable influence. Candidate SNPs associated with rainfall and high temperature were diverse, whereas SNPs associated with specific fire intervals were mainly fixed in one allele. Gene annotation further revealed four genes with functions in stress tolerance, the regulation of stomatal opening and closure, energy use, and morphogenesis with adaptation to climate and fire intervals. B. attenuata may tolerate further changes in rainfall and temperature through evolutionary adaptations based on their adaptive genetic variation. However, the capacity to survive future climate change may be compromised by changes in the fire regime

Ectopic expression of ADP ribosylation factor 1 (SaARF1) from smooth cordgrass (Spartina alterniflora Loisel) confers drought and salt tolerance in transgenic rice and Arabidopsis

Salinity and drought are two very important abiotic stressors that negatively impact the growth and yield of all sensitive crop plants. Genes from halophytes have been shown to be useful to engineer crop plants that can survive under adverse soil and water conditions. The present report establishes, for the first time, the physiological role of a class one ADP ribosylation factor gene (SaARF1) from the halophyte Spartina alterniflora (smooth cordgrass) in imparting salinity and drought stress tolerance when expressed in both monocot (rice) and dicot (Arabidopsis) systems. The Arabidopsis and rice plants overexpressing ARF1 are many-fold more tolerant to salt and drought than wild-type (WT) plants. The transgenics exhibited improved growth and productivity relative to WT through tissue tolerance by maintaining higher relative water content and membrane stability, and higher photosynthetic yield by retaining higher chlorophyll concentration and fluorescence under stress conditions compared to WT. These findings indicated that genes from halophyte resources can be useful to engineer and improve salt and drought stress tolerance in both monocot and dicot plants. © 2013 Springer Science+Business Media Dordrecht

Agrobacterium -mediated engineering for sheath blight resistance of indica rice cultivars from different ecosystems

A concise T-DNA element was engineered containing the rice class-I chitinase gene expressed under the control of CaMV35S and the hygromycin phosphotransferase gene (hph) as a selectable marker. The binary plasmid vector pNO1 with the T-DNA element containing these genes of interest was mobilized to Agrobacteriumtumefaciens strain LBA4404 to act as an efficient donor of T-DNA in the transformation of three different indica rice cultivars from different ecosystems. Many morphologically normal, fertile transgenic plants from these rice cultivars were generated after Agrobacterium-mediated transformation using 3-week-old scutella calli as initial explants. Stable integration, inheritance and expression of the chimeric chitinase gene were demonstrated by Southern blot and Western blot analysis of the transformants. Bioassay data showed that transgenic plants can restrict the growth of the sheath blight pathogen Rhizoctonia solani. Bioassay results were correlated with the molecular analysis. Although we obtained similar results upon DNA-mediated transformation, this report shows the potential of the cost-effective, simple Agrobacterium system for genetic manipulation of rice cultivars with a pathogenesis-related (PR) gene

Translational fusion hybrid Bt genes confer resistance against yellow stem borer in transgenic elite vietnamese rice (Oryza sativa L.) cultivars

We have shown the efficacies of translationally fused gene (cry1Ab-1B) under the control of maize ubiquitin promoter and hybrid Bt gene (cry1A/cry1Ac) driven by rice Actin-1 promoter against the yellow stem borer (Scirpophaga incertulas Walker, YSB) insect in rice (Oryza sativa L.). The integration, expression, and functionality of the transgenes were confirmed by Southern, western, and insect bioassay. The bioassay results correlated with the molecular data. The amount of Bt protein (within the range of 0.8-1.3% of the total soluble protein) in the transgenics was sufficient to cause 100% mortality of the neonate larvae of YSB within 1 wk of infestation. The transgenic plants expressing the foreign Bt protein were normal in phenotype with as good seed setting as the nontransgenic control plants. (Résumé d'auteur

Engineering of Bt transgenic rice for insect pest protection

Stem borer is a serious pest that causes considerable yield losses of rice in Asia. Pesticides have been used broadly to control this pest. Transgenic Bt rice for a wide variety of cultivation conditions have been developed and reported on earlier. Wereview work done todevelop Bt rice with multiple Bt genes that have different receptor binding domains, and with a fusion cry gene, cry1B/cry1Ab. Generation of Bt rice has been performed in different cultivars and recently in the hybrid ‘Shanyou 63’, which gains protection against four insect pests. The Bt-rice hybrid line is free of the selectable marker gene, hph, and has been successfully field evaluated in China for 4 years. Transgene pyramiding with Bt genes alone or in combination with other genes for plant protection has been developed in rice. Bt rice in Asia has the potential to provide plant protection while curbing use of pesticides and reducing yield losses from infestation. The deployment of insect protection genes using a gene pyramiding strategy is presented as a vital strategy for maximizing crop protection and countering the development of resistant pests