A field experiment was carried out in order to evaluate genetic diversity of 41 rice genotypes using physiological traits and molecular markers. All the genotypes unveiled variations for crop growth rate (CGR), relative growth rate (RGR), net assimilation rate (NAR), yield per hill (Yhill(-1)), total dry matter (TDM), harvest index (HI), photosynthetic rate (PR), leaf area index (LAI), chlorophyll-a and chlorophyll-b at maximum tillering stage. The CGR values varied from 0.23 to 0.76 gm cm(-2) day(-1). The Yhill(-1) ranged from 15.91 to 92.26 g, while TDM value was in the range of 7.49 to 20.45 g hill(-1). PR was found to vary from 9.40 to 22.34 µmol m(-2) s(-1). PR expressed positive relation with Yhill(-1). Significant positive relation was found between CGR and TDM (r = 0.61**), NAR and CGR (r = 0.62**) and between TDM and NAR (r = 0.31**). High heritability was found in RGR and Yhill(-1). Cluster analysis based on the traits grouped 41 rice genotypes into seven clusters. A total of 310 polymorphic loci were detected across the 20 inter-simple sequence repeats (ISSR) markers. The UPGMA dendrogram grouped 41 rice genotypes into 11 clusters including several sub-clusters. The Mantel test revealed positive correlation between quantitative traits and molecular markers (r = 0.41). On the basis of quantitative traits and molecular marker analyses parental genotypes, IRBB54 with MR84, IRBB60 with MR84, Purbachi with MR263, IRBB65 with BR29, IRBB65 with Pulut Siding and MRQ74 with Purbachi could be hybridized for future breeding program.
Nepenthes ampullaria is a unique carnivorous tropical pitcher plant with the detritivorous capability of sequestering nutrients from leaf litter apart from being insectivorous. The changes in the protein composition and protease activity of its pitcher fluids during the early opening of pitchers (D0 and D3C) were investigated via a proteomics approach and a controlled protein depletion experiment (D3L). A total of 193 proteins were identified. Common proteins such as pathogenesis-related protein, proteases (Nep [EC:3.4.23.12], SCP [EC:3.4.16.-]), peroxidase [EC:1.11.1.7], GDSL esterase/lipase [EC:3.1.1.-], and purple acid phosphatase [EC:3.1.3.2] were found in high abundance in the D0 pitchers and were replenished in D3L samples. This reflects their importance for biological processes upon pitcher opening. Meanwhile, prey-inducible chitinases [EC:3.2.1.14] were found in D0 but not in D3C and D3L samples, which suggests their degradation in the absence of prey. Protease activity assays demonstrated the replenishment of proteases in D3L with similar levels of proteolytic activities to that of D3C samples. This supports a feedback mechanism and signaling in the molecular regulation of endogenous protein secretion, turnover, and activity in Nepenthes pitcher fluids. Furthermore, we also discovered several new enzymes (XTH [EC:2.4.1.207], PAE [EC:3.1.1.98]) with possible functions in cell wall degradation that could contribute to the detritivory habit of N. ampullaria.
Lignification of the plant cell wall could serve as the first line of defense against pathogen attack, but the molecular mechanisms of virulence and disease between oil palm and Ganoderma boninense are poorly understood. This study presents the biochemical, histochemical, enzymology and gene expression evidences of enhanced lignin biosynthesis in young oil palm as a response to G. boninense (GBLS strain). Comparative studies with control (T1), wounded (T2) and infected (T3) oil palm plantlets showed significant accumulation of total lignin content and monolignol derivatives (syringaldehyde and vanillin). These derivatives were deposited on the epidermal cell wall of infected plants. Moreover, substantial differences were detected in the activities of enzyme and relative expressions of genes encoding phenylalanine ammonia lyase (EC 4.3.1.24), cinnamate 4-hydroxylase (EC 1.14.13.11), caffeic acid O-methyltransferase (EC 2.1.1.68) and cinnamyl alcohol dehydrogenase (CAD, EC 1.1.1.195). These enzymes are key intermediates dedicated to the biosynthesis of lignin monomers, the guaicyl (G), syringyl (S) and ρ-hydroxyphenyl (H) subunits. Results confirmed an early, biphasic and transient positive induction of all gene intermediates, except for CAD enzyme activities. These differences were visualized by anatomical and metabolic changes in the profile of lignin in the oil palm plantlets such as low G lignin, indicating a potential mechanism for enhanced susceptibility toward G. boninense infection.
Although a substantial body of evidence suggests that large and old trees have reduced metabolic levels, the search for the causes behind this observation has proved elusive. The strong coupling between age and size, commonly encountered in the field, precludes the isolation of the potential causes. We used standard propagation techniques (grafting and air-layering) to decouple the effects of size from those of age in affecting leaf structure, biochemistry and physiology of two broadleaved trees, Acer pseudoplatanus (a diffuse-porous species) and Fraxinus excelsior (a ring-porous species). The first year after establishment of the propagated plants, some of the measurements suggested the presence of age-related declines in metabolism, while other measurements either did not show any difference or suggested variability across treatments not associated with either age or size. During the second year after establishment, only one of the measured properties (specific leaf area) continued to show some evidence of an age-mediated decline (although much reduced compared to the field), whereas, for some properties (particularly for F. excelsior), even the opposite trend of age-related increases was apparent. We concluded that (1) our plants suffered from grafting shock during year 1 and they gradually recovered during year 2; (2) the results over 2 years do not support the statement that age directly mediates ageing in either species but instead suggest that size directly mediates ageing processes; and (3) neither shoots nor roots of A. pseudoplatanus showed any evidence of senescence.