Physiology and Molecular Biology of Plants

Crocus sativus, a monocot triploid species belonging to the Iridaceae family, is cultivated for its red stigmatic lobes of the carpel that constitute saffron. Flower development has been extensively studied in different plants. Different floral developmental pathways have been deciphered in many plants. In Crocus sativus, flower is the most important part and understanding the pathway underlying the flower development can pave the way for new avenues to improve its productivity and quality. The combination of class A genes (including APETALA1; CsAP1 and APETALA2; CsAP2), class B genes (including APETALA3; CsAP3 and PISTILLATA; CsPI) and class C genes (including AGAMOUS; CsAG) that are active in each whorl, determines the identity of the organs that will later develop in that whorl. CsAP3 is a class B homeotic gene which promotes petal and stamen formation and has a very important role in flower development. It also activates other genes playing pivotal role in flower development. It has been earlier reported that CsAP3 gene has direct role in activation of CsNAP gene which promotes senescence in plants. Present work was focused on study of relative gene expression changes of CsAP3 and CsNAP gene during different stages of flower development. CsAP3 gene expression was found maximum during late-preanthesis stages of stigma development. Expression increases from stage 5 to stage 6 of flower development and then reduces again from stage 6 to stage 7. CsNAP gene had moderate expression during stage 3 to stage 4 transition and its expression increased abruptly from stage 6 to stage 7 of flower development. There is no direct concordance in the expression of CsAP3 and CsNAP gene expression in saffron. We may conclude that some other factor(s) may be responsible for initiation of CsNAP expression and CsAP3 gene may directly/indirectly be involved in regulating the factors responsible for CsNAP activation.

A rapid, reproducible and efficient regeneration method was developed for chickpea (Cicer arietinum L.) using single cotyledon with half embryonal axis as explants. MS medium supplemented with 4 ìM TDZ, 10 ìM 2-iP and 2 ìM kinetin induced 50–100 adventitious buds/shoots after 14 days of culture and elongated on MS medium supplemented with 5 ìM 2-iP and 2 ìM kinetin. Healthy, strong and 100 % rooting was achieved by exposing cut ends of the shoots to 10 sec pulse treatment with 100 ìmoles/ml IBA followed by their transfer to liquid MS basal medium within 10–14 d. 2–3 cm long shoots were most suitable for rooting. Potting-mixture with good aeration and lesser capacity to retain water was most suitable for achieving successful establishment of chickpea plantlets. Garden soil mixed with sand (gravel) and bio-manure in the ratio of 1:1:1 is most suitable for achieving cent percent transplantation success. Cent percent of plantlets got acclimatized, survived in the pots and showed normal growth, development, flowering followed by podding and seeds setting. Harvesting of seeds was done after the pods were fully matured and dry. In this communication, we have demonstrated for the first time that shoot length, pulse treatment of cut ends of shoots with 100 ìmoles/ml IBA and aeration of potting mixture are key factors for rapid micro-propagation and successful establishment of chickpea.

Plant and rhizobacterial interactions contribute partly to a plant’s medicinal properties and are well studied through metagenomics. In this study, 16S rDNA, 18S rDNA, and ITS meta-sequencing were performed using the genomic DNA obtained from the rhizosphere of Caesalpinia bonducella—a medicinal shrub widely used to treat polycystic ovary syndrome (PCOS). Of the 665 Operational Taxonomic Units (OTUs) obtained from 16S rDNA sequencing, 23.9% comprised of microbes that increase the therapeutic value of plants (Bacillus, Paenibacillus), 6.4% belonged to stress and drought tolerant microbes (Pseudomonas, Rhizobium, Serratia), 8% belonged to plant-growth promoting rhizobacteria—predominantly Proteobacteria, and Firmicutes and the remaining were the microbes performing various other functions. Alpha diversity indexing by GAIA-metagenomics tool revealed the presence of a highly diverse group of microbes in the rhizosphere of C. bonducella; Chao.1 index (665), Shannon Weiner index (3.53), Simpson index (0.83) and Fisher index (106.13). The highly diverse microbes lingering around the roots of C. bonducella could possibly be due to a strong symbiotic association with the plant; root exudates nourish the microbes and the microbes in turn enrich the medicinal value of the plant.

Zingiber officinale is a model spice herb, well known for its medicinal value. It is primarily a vegetatively propagated commercial crop. However, considerable diversity in its morphology, fiber content and chemoprofiles has been reported. The present study explores the utility of EST-derived markers in studying genetic diversity in different accessions of Z. officinale and their cross transferability within the Zingiberaceae family. A total of 38,115 ESTs sequences were assembled to generate 7850 contigs and 10,762 singletons. SSRs were searched in the unigenes and 515 SSR-containing ESTs were identified with a frequency of 1 SSR per 25.21 kb of the genome. These ESTs were also annotated using BLAST2GO. Primers were designed for 349 EST-SSRs and 25 primer pairs were randomly picked for EST SSR study. Out of these, 16 primer pairs could be optimized for amplification in different accessions of Z. officinale as well as other species belonging to Zingiberaceae. GES454, GES466, GES480 and GES486 markers were found to exhibit 100% cross-transferability among different members of Zingiberaceae.

Cells of Anabaena sp. PCC 7120, a low desiccation tolerant cyanobacterium, was subjected to prolonged desiccation and effect of loss of water was examined on production of osmolytes, and antioxidant response as well as on overall viability in terms of photosynthetic activity. During dehydration (22 h), the organism maintained about 98.5 % loss of cellular water, yet cells remained viable as about 30 % of photosynthetic O2-evolution activity resumed upon hydrating (1 h) such cells. In desiccated state, cyanobacterial cells accumulated osmolytes within 1 h though their contents decreased thereafter. The highest levels of trehalose (179 nmol mg−1 protein), sucrose (805 nmol mg−1 protein) and proline (23.2 nmol mg−1 protein) were attained within 1 h. Chlorophyll a and carotenoid contents also increased within 1 h but phycocyanin level showed opposite trend. The oxygen-evolving activity declined in desiccated cyanobacterial biomass while rehydration led to instant recovery, indicating that cells protect the photosynthetic machinery against desiccation. Notwithstanding, activities of antioxidant enzymes (catalase, peroxidase and superoxide dismutase) attained their peaks after 3 h of desiccation, though within 10 min of rehydration, their levels returned back close to basal activities of the cultured cells. We propose that onset of osmolyte production in conjunction with upshift of antioxidant enzymes apparently protects the cyanobacterial cells from desiccation stress.

Plants like other organisms are affected by environmental factors. Cadmium, copper and zinc are considered the most important types of pollutants in the environment. In this study, a comparison of growth and biochemical parameters between the crop wild relative (CWR) Solanum nigrum versus its cultivated relative Solanum lycopersicum to different levels of Cu, Zn and Cd stress were investigated. The presence of ZnSO4 and CuSO4 in Murashige and Skoog medium affected severely many growth parameters (shoot length, number of roots and leaves, and fresh weight) of both S. nigrum and S. lycopersicum at high levels. On the other hand, CdCl2 significantly reduced most of the studied growth parameters for both species. S. nigrum exhibited higher tolerance than S. lycopersicum for all types of stress. In addition, results show that as stress level increased in the growing medium, proline content of both S. nigrum and S. lycopersicum increased. A significant difference was observed between the two species in proline accumulation as a result of stress. In addition, a higher accumulation rate was observed in the crop wild relative (S. nigrum) than in cultivated S. lycopersicum. Changes in Inter-simple sequence repeat (ISSR) pattern of CuSO4 treated S. nigrum and S. lycopersicum plants were also observed. In conclusion, based on growth and biochemical analysis, S. nigrum showed higher level of metals tolerance than S. lycopersicum which indicates the possibility of using it as a crop wild relative for S. lycopersicum.

Knema andamanica is a red-listed endemic medicinal species of Myristicaceae restricted to Andaman and Nicobar (A&N) Islands, India. This species is used in tribal medicines and has immense bioprospective potential. With a view to generate suitable genomic markers for classification and identification, we have generated RAPD, SCAR and conserved 18S rDNA markers from K. andamanica. A unique 585 bp fragment, that distinguished it from seven other related species of Myristicaceae was first amplified using the random primer OPE 06 and converted to SCAR marker (GenBank accession # JN228256). The conserved sequences of 18S rDNA loci from K. andamanica were also amplified and sequenced (GenBank accession #JN228265). The sequence revealed deviations including 18 variable regions and 15 indels that were unique to K. andamanica. These markers can help in definite identification of K. andamanica even at the juvenile stages.