Rorippa indica Regeneration via Somatic Embryogenesis Involving Frog Egg-like Bodies Efficiently Induced by the Synergy of Salt and Drought Stresses

NAA at a high concentration promotes efficient plant regeneration via direct somatic embryogenesis and SE-mediated transformation system in Ranunculus sceleratus

The novel methods for efficient plant regeneration via direct somatic embryogenesis (SE) and SE-mediated transformation system under high concentration of NAA in Ranunculus sceleratus were established. On MS media containing a high concentration of NAA (10.0 mg/L) in the dark, all inoculated explants (root, stem and leaf) formed somatic embryos at high frequencies, respectively, 66.03, 126.47 and 213.63 embryoids per explant, and 100% of the embryoids developed into plantlets on 1/2 MS rooting media. Morphological and histological analyses revealed that SE in R. sceleratus followed a classical pattern. All inoculated explants can be used as receptors for genetic transformation in R. sceleratus, through direct SE-mediated method after Agrobacterium infection. RcLEC1-B, as a marker gene, changed the number and morphology of flower organs and the development of cuticle in R. sceleratus, which indicated that the efficient transgenic system of R. sceleratus was established. To our knowledge, this is the first observation that both direct SE and transgenic transformation system, via induction of a single plant growth regulator, have been successfully constructed in R. sceleratus.

Efficient and reproducible somatic embryogenesis and micropropagation in tomato via novel structures - Rhizoid Tubers

A dual in vitro regeneration system consisting of indirect organogenesis and somatic embryogenesis (SE), applicable to several varieties of tomato—Solanum lycopersicum (cv. Riogrande, cv. Roma, hybrid 17905 and model cv. M82) has been established. This system is both improved and highly reproducible compared to current methods. Callus initiation, plant regeneration and SE was developed for one-week-old cotyledon explants. Indirect organogenesis via callus induction (CI) was developed for all four varieties of tomato used in this study. One-week-old tomato seedlings were used as a source of cotyledon and hypocotyl segments as explants. The explants were subsequently cultured on Murashige and Skoog (MS) medium supplemented with different combination and concentrations of plant growth regulators (PGRs). Substantial trends in regeneration and propagation response were observed among the varieties and treatments. For commercial varieties cvs. Riogrande and Roma, maximum CI was observed at 2 weeks in CIMT⁹ (0.5 mg/L NAA, 1 mg/L BAP) and CIMT¹² (2 mg/L IAA, 2 mg/L NAA, 2 mg/L BAP, 4 mg/L KIN). However, cv. M82 responded after 4 weeks to a combination of treatments CIMT⁹ (0.5 mg/L NAA + 1 mg/L BAP) and CIMT¹³ (2 mg/L IAA + 2 mg/L NAA + 2 mg/L BAP + 4 mg/L ZEA) for the production of calli. Subsequent shoot and root organogenesis were optimized for all four varieties. Cv. Riogrande, exhibited fastidious in vitro regeneration potential and selected for induction of somatic embryos via SE involving novel structure: rhizoid tubers (RTBs). Numerous fine hair like rhizoids (~23/explants) were first developed from cotyledon and hypocotyl explants cultured on MS medium supplemented with 0.5 or 2 mg/L NAA at pH 4.0 in dark conditions. Further incubation of each rhizoid under light conditions on MS media supplemented with 5 mg/L TDZ or BAP at pH 4.0 led to the formation of a novel structure—rhizoid Tubers (RTBs). Thus, as evident from histology, SE in Riogrande tomato species requires a medium with pH of (4.0) and higher concentration of cytokinins (BAP/TDZ) to form on average 40–45 RTBs from both explants. Histological and morphological studies revealed that RTBs develop through different stages of embryogenesis to multiple plantlets, on MS medium with 5 mg/L TDZ/BAP at normal pH (5.8). The results obtained indicated that the induced somatic embryos of tomato with lower pH are a more efficient mode of propagation than the organogenesis with or without callus formation. The RTBs led to a complete plantlets regeneration in 45 days compared to indirect organogenesis at 60 days.

Effect of regional wind circulation and meteorological factors on long-range migration of mustard aphids over indo-gangetic plain

Mustard aphids are a serious problem for Brassica oilseed in India causing up to 90% of the crop damage. It was hypothesized that Aphids migrate into the Indo Gangetic plain (IGP) from hilly regions of every year. Exact source and migration pattern of this pest is unknown till date. During their long range migration they infested various places over IGP, which fall on their way of migration. The wind, blown from the hilly regions helps aphids to migrate. Meteorological parameters play a crucial role in this migration of aphids. In this study, we have done the 24 hours air-mass backward trajectory at 100 m above ground level (agl) to detect the source regions of mustard aphids. We have found that mainly Western Himalayan hilly regions act as the source of mustard aphids for IGPs. The dependence upon the micro-meteorological parameters and population dynamics are analyzed and discussed elaborately in this work. In this study, we have proposed the 'Hop and Fly' behavior of mustard aphid and further discussed how this migrating behavior could help us to reduce the yield loss of Brassica.