Activation of drought tolerant traits in crops: endophytes as elicitors.

Drought challenges crop production worldwide. The issue is aggravated by frequent drought episodes and unpredictable rainfall patterns associated with global climate change. While the efforts to breed drought-resistant crop varieties are progressing, the need of the hour is immediate strategies to sustain the yields of existing ones. As per recent studies, stress adaptive traits can be activated using specific elicitors. Endophytes that inhabit host plants asymptomatically are natural elicitors/bio-stimulators capable of activating host gene expression, conferring several benefits to the hosts. This review discusses the scope of using trait-specific endophytes in activating drought adaptive traits in crop varieties.

Universal stress protein-like gene from mulberry enhances abiotic stress tolerance in Escherichia coli and transgenic tobacco cells.

Universal stress proteins (USPs) are a conserved group of proteins initially identified and characterized in bacteria. USPs are induced under multiple stresses, and are important for stress acclimation. We cloned a USP-like gene designated as MaUSP1-like from mulberry and expressed in bacteria and tobacco to examine its relevance in abiotic stress tolerance. Escherichia coli and tobacco cells expressing MaUSP1-like gene were exposed to different abiotic stresses, and cell survival and growth was recorded to assess the stress effects. MaUSP1-like gene conferred tolerance to E. coli cells under NaCl-induced salt stress, PEG8000-induced desiccation stress, cadmium chloride-induced heavy metal stress, and heat stress. Overexpression of MaUSP1-like sustained cell division and growth in tobacco cells under salt stress. The results demonstrate that MaUSP1-like gene is capable of conferring cellular level tolerance in both prokaryotic and eukaryotic systems, under abiotic stress. The finding opened up an option to argue that maintenance of cellular level tolerance is crucial for sustenance of growth under stress and cellular level tolerance can be improved by overexpressing genes like USPs.

Assessing the life cycle of pests, Diaphania pulverulentalis (Hampson) and Maconellicoccus hirsutus Green, reared on transgenic mulberry.

The study aims at investigating the growth and development of two common pests in mulberry namely the leaf roller (Diaphania pulverulentalis) and mealy bug (Macconellicoccus hirsutus), reared on transgenic mulberry plants in comparison with the wild type plants V1, a ruling variety. Both the pests completed normal life cycle on all the four different transgenic plants (Ip::HVA1, Cp::HVA1, Cp::BCH1, Cp::osmotin and Ip::osmotin) expressing three different transgenes (HVA1, BCH1 and osmotin) in the presence of the marker gene NPTII. There was no significant difference in the incubation period of the eggs, growth of first to fifth instar larvae and total larval period of the leaf roller reared on transgenic and non-transgenic mulberry. The pre-pupal, pupal, adult stages and adult fecundity also did not differ. The variations in the duration of the different nymphal instars, and their total duration was not significant in the case of mealy bug, when reared on the transgenics. The adult longevity and total life span of female mealy bugs, and the pupal period and total life span of the male bugs were on par with those reared on the wild type plants. The study indicates that the life cycle of both the pests, which are common in a mulberry ecosystem, were not affected by feeding on any of the transgenic mulberry plants at any stage of their growth and development.

Mulberry (Morus spp.) has the features to treat as a potential perennial model system.

Mulberry (Morus spp.), a commercially exploited tree species as the host of monophagous pest silk worm (Bombyx mori), belongs to the family Moraceae. The domesticated tree has diverse beneficial characters such as traits associated with rapid growth and biomass production, plant insect/microbe interaction, abiotic stress tolerance and the traits associated with nutritional and medicinal values; some of which have been exploited. Draft genome of Morus notabilis has been sequenced and a large volume of transcriptome and genomic resources have been generated. In this review an attempt has been made to examine the options for considering mulberry as another tree model system to study unique traits associated with perennial systems. The diverse traits and features in mulberry suggest that the system can be a "comprehensive trait integrated tree system" quite different from other model tree systems.

An Approach to Function Annotation for Proteins of Unknown Function (PUFs) in the Transcriptome of Indian Mulberry.

The modern sequencing technologies are generating large volumes of information at the transcriptome and genome level. Translation of this information into a biological meaning is far behind the race due to which a significant portion of proteins discovered remain as proteins of unknown function (PUFs). Attempts to uncover the functional significance of PUFs are limited due to lack of easy and high throughput functional annotation tools. Here, we report an approach to assign putative functions to PUFs, identified in the transcriptome of mulberry, a perennial tree commonly cultivated as host of silkworm. We utilized the mulberry PUFs generated from leaf tissues exposed to drought stress at whole plant level. A sequence and structure based computational analysis predicted the probable function of the PUFs. For rapid and easy annotation of PUFs, we developed an automated pipeline by integrating diverse bioinformatics tools, designated as PUFs Annotation Server (PUFAS), which also provides a web service API (Application Programming Interface) for a large-scale analysis up to a genome. The expression analysis of three selected PUFs annotated by the pipeline revealed abiotic stress responsiveness of the genes, and hence their potential role in stress acclimation pathways. The automated pipeline developed here could be extended to assign functions to PUFs from any organism in general. PUFAS web server is available at http://caps.ncbs.res.in/pufas/ and the web service is accessible at http://capservices.ncbs.res.in/help/pufas.