P. N. Sivalingam

GBF3 transcription factor imparts drought tolerance in Arabidopsis thaliana

Drought transcriptome analysis of finger millet (Eleusine coracana) by cDNA subtraction identified drought responsive genes that have a potential role in drought tolerance. Through virus-induced gene silencing (VIGS) in a related crop species, maize (Zea mays), several genes, including a G-BOX BINDING FACTOR 3 (GBF3) were identified as candidate drought stress response genes and the role of GBF3 in drought tolerance was studied in Arabidopsis thaliana. Overexpression of both EcGBF3 and AtGBF3 in A. thaliana resulted in improved tolerance to osmotic stress, salinity and drought stress in addition to conferring insensitivity to ABA. Conversely, loss of function of this gene increased the sensitivity of A. thaliana plants to drought stress. EcGBF3 transgenic A. thaliana results also suggest that drought tolerance of sensitive plants can be improved by transferring genes from far related crops like finger millet. Our results demonstrate the role of GBF3 in imparting drought tolerance in A. thaliana and indicate the conserved role of this gene in drought and other abiotic stress tolerance in several plant species.

Molecular markers to distinguish ‘Thar Shoba’, a variety of khejri [Prosopis cineraria (L.) Druce], from trees in natural populations

ABSTRACT Prosopis cineraria (L.) Druce, commonly called khejri, is an important multipurpose, leguminous tree of the Thar Desert. ‘Thar Shoba’ is a variety of khejri without thorns which was developed as a vegetable. In order to develop markers for varietal identification, 80 RAPD primers were tested, of which nine were polymorphic between ‘Thar Shoba’ and trees in a natural population of khejri. Phenetic analysis revealed that ‘Thar Shoba’ formed a separate cluster from the natural population with similarity coefficients of 0.57–0.78. The 10-mer primers OPBE05, OPBA13, OPA12, and OPA14 were each found to differentiate ‘Thar Shoba’ from the natural population by one amplicon. These differential amplicons were sequenced and SCAR markers were developed based on the sequences that differentiated ‘Thar Shoba’ from the natural population. Natural populations of khejri from different regions of the Thar Desert, and clonally multiplied ‘Thar Shoba’ plants in the ICAR-CIAH bud-wood genebank, were used to validate these primers. These markers will be useful in further developing the bud-wood genebank, and for certification, identification, and protection of the khejri variety ‘Thar Shoba’.

Characterization of Prosopis cineraria (L.) Druce germplasm with suitable horticultural traits from the hot arid region of Rajasthan, India

Sixteen germplasm accessions of Prosopis cineraria with suitable horticultural traits were identified from north-western Rajasthan, India, propagated clonally by budding on seedling rootstock and maintained in the field gene bank. Morphological characterization of seven-year-old trees of these accessions by 21 traits indicated a lot of variation among the accessions tested. Higher number of flowers per raceme was found in accession CIAH/K2, higher width of ripened pod in CIAH/K5, higher number of seeds per pod in CIAH/K12 and a higher weight of seed per pod in CIAH/K6. Overall, CIAH/K16 was found to be a superior genotype for most of the useful traits. High significant positive correlation was obtained with traits useful for horticultural values. Out of 62 random decamer primers for random amplification (RAPD) reaction, and four minisatellite core sequence for direct amplification of minisatellite DNA (DAMD) screened with these accessions, 12 RAPD and 2 DAMD primers were found polymorphic. Average polymorphism resolved by these markers among the accessions was 93.2%. Genetic diversity revealed by Jaccard’s co-efficient was between 0.11 and 0.77, and four major clusters were identified among these accessions by phylogenetic analysis using NTSYSpc-2.02e software. This study shows the existence of high genetic diversity within these accessions.