Influence of the functional traits of seeds on germination dynamics and morphofunctional pattern of the seedlings

Aiming to compare morphofunctional features related to dispersion and establishment of plants, this study evaluated seed biometry and biomass, as well as germination and emergence potential in eight plant species native to the Semideciduous Seasonal Forest. Biometric measurements and biomass of seeds were obtained with a caliper and a precision scale.Afterwards, they were subjected to a germination test in BOD chambers under constanttemperature and 12hoursphotoperiod, and sown in styrofoam trays containing organic substrate and sand, kept in full sunlight.Data from germination and emergence was subjected to cluster analysis, according to the functional morphotype of the seedling.Most species presented seeds with a rounded shape, uniform staining at the mature stage, varied coat consistency, two types of dispersal syndromes (anemochory and zoochory) and four morphofunctional patterns in developing seedlings (crypto-hypogeal-storers, crypto-epigeal-storers, phanero-epigeal-storers and phanero-epigeal-foliaceous). The species belonging to group I (Albizia niopoides, Cedrela fissilis, Pterogyne nitensand Randia ferox) have foliaceous photosynthetic cotyledons and group II (Cabralea canjerana, Eugenia pyriformis, Inga laurinaand Poecilantheparviflora) have a reserve cotyledon. Species of group I had higher means in the percentage and rate of germination, less variability and amplitude of days for seedlings emergence. On the other hand, species of group II showed higher mean values in seed biometry and biomass. Thus, seeds with foliaceous cotyledons have an optimized development because of luminosity, whereas seeds with reserve tend to have slower development, remaining at the seedling stage for a longer time.

Lipophilic metabolite profiling of maize and sorghum seeds and seedlings, and their pest spotted stem borer larvae: A standardized GC-MS based approach.

In order to better understand the biochemical interactions and to identify new biomarkers for plant resistance against insects, we proposed a suitable lipophilic profiling method for insects and their host plants. The critical components of GC-MS based analysis are: sample amount, extraction, derivatization, temperature gradient, run time, and identification of peaks. For lipophilic metabolite profiling of maize and sorghum, and their insect pest, spotted stem borer larvae, we recommend 100 mg sample weight for seeds and insect samples (whole insect body), and 200 mg for seedlings. Maize and sorghum seeds required less time for fat extraction in comparison to their seedlings and the pest fed on these seedlings. GC-MS was standardized for better separation and intensity of peaks using different temperature gradients in the range of 180-300 C. A total of 48 lipophilic compounds encompassing various classes based on their functional groups such as fatty acids, fatty alcohols, hydrocarbons, sterols and terpenoids, vitamin derivative, etc. were separated in the seedlings (30), seeds (14), and the pest (26) in the retention time range of 3.22 to 29.41 min. This method could be useful to study nutritional aspects of different field crops in relation to various stresses apart from the analysis of lipophilic compounds for better understanding of insect-plant interactions.

Protection against photooxidative damage provided by enzymatic and non-enzymatic antioxidant system in sorghum seedlings.

Effect of photoinhibition of sorghum leaves and isolated chloroplasts on chlorophyll fluorescence, peroxidation of thylakoid lipids and activity of antioxidant enzymes were studied. Photoinhibition of intact leaves and isolated chloroplasts decreased Fv/Fm ratio and qP, while qN increased. Photoinhibitory damage was more at 5 degrees C than at 30 degrees or 50 degrees C. Peroxidation of thylakoid lipids was 5 times greater when photoinhibited at 50 degrees C compared to control. Photoinhibition of chloroplasts under low oxygen condition or when supplemented with anti-oxidants (beta-carotene, ascorbate and GSH) resulted in significantly less damage to photosynthesis (Fv/Fm ratio) and peroxidation level. Photoinhibition also resulted in many fold increase in the activity of superoxide dismutase (SOD) and ascorbate peroxidase (APX) and decrease in catalase. Data presented here suggest that photoinhibition resulted in production of oxygen radicals and photoinhibition of chloroplasts in the presence of low oxygen level or when supplemented with antioxidants decreased the damage to Fv/Fm ratio and peroxidation level to a great extent since former prevented the formation of oxygen radicals and later could scavenge the oxygen radicals thus the protection. Increase activity of SOD and APX may also be to metabolise the oxygen radicals produced during photoinhibition treatment, thereby, protecting the seedlings against photooxidative damage.

Micropropagation of Terminalia arjuna Roxb. from cotyledonary nodes.

Cotyledonary node explants excised from 21 day old seedlings of T. arjuna produced multiple shoots when cultured on full strength MS or modified MS (1/2 strength major salts and Fe-EDTA) medium supplemented with different concentrations (0.1-1.0 mg/l) of BAP. Maximum 8.9 shoots/explant could be recorded after 30 days of inoculation on modified MS medium supplemented with BAP (0.5 mg/l). A proliferating shoot culture was established by reculturing the original cotyledonary nodes (2-3 times) on shoot multiplication medium after each harvest of the newly formed shoots. Shoots (each having 2-3 nodes/shoot) thus obtained were also used as a source of nodal explant that gave rise to 1-2 shoots when cultured on modified MS+BAP (0.5 mg/l) medium. Thus, 45-55 shoots could be obtained after 60 days of culture initiation from a single cotyledonary node. About 88% shoots rooted well after 15 hr pulse treatment with IBA (1 mg/l) in liquid MS medium followed by transfer to modified MS medium without IBA. About 80% of these plantlets were successfully acclimatized in plastic pots containing sand and soil mixture and 70% plantlets transferred in the field those survived even after 6 months of transplantation.