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Influence of leaf types on canopy architecture and grain yield in selected crosses of spring wheat Triticum aestivum L.
The effects of erect leaf canopies on enhancing grain yield in wheat is not
understood. The main objective of this study was to understand the effect of leaf
angle on grain yield by comparing randomly derived-lines from crosses of erect
and droopy leaf spring wheats. Nine traits associated with canopy architecture
were evaluated to determine their influence on grain yield and its major
components. The experiment was conducted at Centro de Investigacions
Agricola del Nororeste (CIANO) located near Obregon, Mexico.
When all F6 lines are considered, there were no consistent differences in
grain yield between different canopy types. Parental sources of erect and
droopy leaf type did, however, have an influence on the interrelationship
between components of grain yield. In the highest yielding cross, F6:2 lines
showed positive complementary relationships between grain yield, grains/m²,
harvest index, and 100 kernel weight. That erect leaf F6:2 lines were included in
the top and lowest grain yielding groups indicates that factors other than leaf
erectness may be more important in determining grain yield.
In a separate experiment, paired F6:2 lines with contrasting leaf types of
crosses between erect and droopy leaf parents were derived from individual F2
plants. Erect leaf lines showed a slight grain yield advantage over their droopy
leaf counterparts. The differences in grain yield were associated with high
grains/m², high harvest index, and slower leaf senescence. Erect leaf F6:2 lines
also showed a higher crop growth rate. However, the grain yield advantage in
erect leaf F6:2 lines was independent of efficiency of converting solar radiation
into dry matter, crop growth rate, extinction coefficient, and leaf area index.
Erect leaf parents and erect leaf F6:2 lines showed higher susceptibility to
leaf tip burning. Negative associations of leaf tip burning with grain yield and its
components were found among erect leaf F6:2 lines. Leaf tip burning reduced
100 kernel weight, and consequenctly yield.
The erect leaf habit in wheat may have some beneficial impact on grain
yield, provided appropriate parental sources can be identified. Selection for
high grains/m² and 100 kernel weight in erect leaf populations may maximize
selection response
Recloning of regenerated plantlets from elite oil palm (Elaeis guineensis Jacq.) cv. Tenera
Plant regeneration in oil palm cv. Tenera via somatic embryogenesis was conducted using regenerated plantlets as an explant source. Explants from different positions – apex, middle and basal segments of regenerated plantlets – were cultured in N6 medium supplemented with 100, 120 and 140 mg/L 2,4-dichlorophenoxyacetic acid (2,4-D) in the presence of activated charcoal. The production of embryogenic calli was affected by 2,4-D concentration and explant position; 2,4-D 120 mg/L was the most effective (62.53%) in inducing embryogenic calli from the basal segment 5 months after inoculation. After 3 months of culture in embryo maturation medium, an average of 36 ± 8 somatic embryos per embryogenic callus was obtained. When transferred to plant regeneration medium for 3 to 4 months, these somatic embryos differentiated into shoots, with ranges of 6 to 40 and 4 to 32 shoots on the medium with and without 2-isopentyladenine (6-dimethylaminopurine) (2iP), respectively. Plantlets (6 to 8 cm height) with balanced shoots and roots were obtained after 12 to 14 months. Histological analysis confirmed the initiation, development and germination of somatic embryos from explants of regenerated plantlets. Simple sequence repeat (SSR) analysis showed the genetic identity and uniformity between the first and second regenerated plantlets at five SSR loci.Key words: Elaeis guineensis Jacq., genetic identity, regenerated plantlets, somatic embryogenesis, SSR marker
Sequence Variation and Haplotype Structure in the Lox3 Gene of Oryza sativa L
ABSTRACT For 24 rice (Oryza sativa L.) varieties, genetic variation was studied of the Lox3 gene in samples of the two subspecies, japonica and indica. The genomic DNA was amplified, followed by DNA sequencing to detect sequence variation. A total of 13 single nucleotide polymorphisms (SNPs) was detected in the exon 4 containing lipoxygenase domain. The nucleotide diversity in the Lox3 region of O. sativa was 0.00112, which could be classified into ten haplotypes. Phylogenetic relationships among varieties were inferred using neighbor-joining methods. Cluster analysis showed that all populations could be clustered into five groups. The results also revealed that the haplotype of Oryza sativa ssp.japonica rice is distinctively separated from that of Oryza sativa ssp.indica rice
Curated genome annotation of Oryza sativa ssp. japonica and comparative genome analysis with Arabidopsis thaliana
We present here the annotation of the complete genome of rice Oryza sativa L. ssp. japonica cultivar Nipponbare. All functional annotations for proteins and non-protein-coding RNA (npRNA) candidates were manually curated. Functions were identified or inferred in 19,969 (70%) of the proteins, and 131 possible npRNAs (including 58 antisense transcripts) were found. Almost 5000 annotated protein-coding genes were found to be disrupted in insertional mutant lines, which will accelerate future experimental validation of the annotations. The rice loci were determined by using cDNA sequences obtained from rice and other representative cereals. Our conservative estimate based on these loci and an extrapolation suggested that the gene number of rice is ~32,000, which is smaller than previous estimates. We conducted comparative analyses between rice and Arabidopsis thaliana and found that both genomes possessed several lineage-specific genes, which might account for the observed differences between these species, while they had similar sets of predicted functional domains among the protein sequences. A system to control translational efficiency seems to be conserved across large evolutionary distances. Moreover, the evolutionary process of protein-coding genes was examined. Our results suggest that natural selection may have played a role for duplicated genes in both species, so that duplication was suppressed or favored in a manner that depended on the function of a gene