Methods for a Quantitative Comparison of Gravitropism and Posture Control Over a Wide Range of Herbaceous and Woody Species

Quantitative measurements of plant gravitropic response are challenging. Differences in growth rates between species and environmental conditions make it difficult to compare the intrinsic gravitropic responses of different plants. In addition, the bending movement associated with gravitropism is competing with the tendency of plants to grow straight, through a mechanism called proprioception (ability to sense its own shape). Disentangling these two tendencies is not trivial. Here, we use a combination of modeling, experiment and image analysis to estimate the intrinsic gravitropic and proprioceptive sensitivities of stems, using Arabidopsis as an example.

De novo in vitro shoot morphogenesis from shoot tip-induced callus cultures of Gymnema sylvestre (Retz.) R.Br. ex Sm

Background

Gymnema sylvestre is a medicinal woody perennial vine known for its sweetening properties and anti-diabetic therapeutic uses in the modern and traditional medicines. Its over-exploitation for the therapeutic uses and to meet the demand of pharmaceutical industry in raw materials supply for the production of anti-diabetic drugs has led to considerable decline in its natural population.

Results

An efficient system of shoot bud sprouting from nodal segment explants and indirect plant regeneration from apical meristem-induced callus cultures of G. sylvestre have been developed on Murashige and Skoog (MS) medium amended with concentrations of cytokinins. Of the three growth regulators tested, N⁶-benzylaminopurine (BAP) was the most efficient and 2.0 mg L⁻¹ gave the best shoot formation efficiency. This was followed by thidiazuron (TDZ) and kinetin (Kin) but, most of the TDZ-induced micro shoots showed stunted growth. Multiple shoot formation was observed on medium amended with BAP or TDZ at higher concentrations. The produced micro shoots were rooted on half strength MS medium amended with auxins and rooted plantlets acclimatized with 87% survival of the regenerates.

Conclusions

The developed regeneration system can be exploited for genetic transformation studies, particularly when aimed at producing its high yielding cell lines for the anti-diabetic phytochemicals. It also offers opportunities for exploring the expression of totipotency in the anti-diabetic perennial vine.

Isoflavone production in hairy root cultures and plantlets of Trifolium pratense

OBJECTIVES

The aim of this study was to develop a Trifolium pratense hairy root (HR) production protocol and select HR lines with high isoflavone yield following elicitor treatments.

RESULTS

We obtained 13 independent HR lines, producing approximately three times more isoflavonoids than seedlings (3.3 mg/g dry weight) and in which 27 isoflavonoids were detected. Each HR line had its own isoflavonoid profile. These lines produced as major components daidzein, genistein, formononetin and biochanin A. Sucrose, salicylic acid (SA), yeast extract (YE) and flagellin 22 (flg22) were tested as elicitors. Using SA 140 mg/L, allowed the maximum isoflavonoid production in plantlets (11.9 mg/g dry weight) but reduced root growth, possibly as a result of its toxicity. The highest isoflavone production in HR (27.9 mg/g dry weight) was obtained using sucrose 60 g/L, for 3.5 days.

CONCLUSION

This work reports the high production of various isoflavonoids with T. pratense elicited HR cultures.

Optimization of regeneration using differential growth regulators in indica rice cultivars

Paddy is a staple crop and being grown in major parts of India, but similarly it is facing some major challenges like abiotic stresses (drought, salinity, etc.) by which its productivity is greatly affected. De-husked seeds of 21 cultivars of indica rice were cultured onto MS medium for screening of their micropropagation capabilities. All the selected cultivars are being cultivated by farmers of Andhra Pradesh and Rajasthan states of India, these cultivars bear good quality of grain and high yield. Similarly, both states are facing the problem of drought so; we selected these cultivars for the micropropagation and transformation studies. The induction of callus and regeneration in these selected cultivars were achieved on MS culture medium with supplementation of various growth regulators. Maximum callus induction and regeneration frequency were observed in Sambha mahsuri at the concentration of 3.0 mg L⁻¹ of 2,4-D and BAP (5.0 mg L⁻¹) while the moderate response achieved in other cultivars of rice. Sambha mahsuri showed promising results in terms of callus induction frequency, and regeneration potentialities of embryogenic callus so, there is need to develop a rice cultivars that could thrive under drought condition if the country is to sustain rice production. Finally, regenerated plantlets were successfully transferred to natural conditions (in pots) after acclimatization.

Induction of somatic embryogenesis and plantlets in tendrils of Vitis vinifera L

Somatic embryogenesis was observed in callus initiated from tendril explants of Vitis vinifera L. cvs. Thompson, Sonaka and Tas-e-Ganesh on Emershad and Ramming medium supplemented with 1 µM 6-benzylaminopurine. Low-frequency conversion to shoots was obtained in the third and fourth subculture on the same medium. Emerging shoots subsequently formed complete plantlets on liquid rooting medium containing 1 µM indole-3-acetic acid. The possible use of tendrils as a novel explant for somatic embryogenesis in grape is discussed.

In vitro multiplication ofVanilla planifolia using axillary bud explants

A clonal propagation method has been developed for efficient multiplication ofVanilla planifolia. Multiple shoots were developed from axillary bud explants using semi-solid Murashige and Skoog (MS) medium supplemented with N⁶-benzyladenine (BA, 2 mg l^-1) and α-naphthaleneacetic acid (NAA, 1 mg l^-1). The multiple shoots were transferred to agitated liquid MS medium with BA at 1 mg l^-1 and NAA at 0.5 mg l^-1 for 2-3 weeks, and subsequently cultured on semi-solid medium. Using this method, an average of 42 shoots were obtained from a single axillary bud explant over a period of 134 days. Use of an intervening liquid medium has been found to enhance multiplication of shoots inV. planifolia.