William José da Silva

Photosynthetic O2 evolution in maize inbreds and their hybrids can be differentiated by open photoacoustic cell technique

Abstract Photosynthetic efficiency is considered one of the traits potentially suitable to differentiate hybrids from their inbred lines. Previous evaluations concerning photosynthetic efficiencies of maize (Zea mays L.) plants in the field have shown inconsistent and contradictory data. In this work, we attempted to study photosynthetic O2 evolution through photoacoustic spectroscopy in intact undetached leaves of dark-adapted seedlings of inbreds and their hybrids. The results indicate that photosynthetic efficiencies of inbreds and hybrids can be differentiated by photoacoustic measurements of oxygen evolution, providing a parameter that might prove useful in evaluating plant genotypes.

In vivo and in situ measurements of spectroscopic and photosynthesis properties of undetached maize leaves using the open photoacoustic cell technique

Abstract A new and highly sensitive method, based on the photoacoustic effect, is described for in vivo and in situ studies of photosynthetic activity of undetached leaves. The general utility of this simple photothermal method is demonstrated by examining the spectroscopy and photosynthetic activity of green, striped, and albino plants of maize (Zea mays L.).

Photoacoustic assessment of the in vivo genotypical response of corn to toxic aluminium.

An open-cell photoacoustic (OCPA) spectroscopic technique is described which can assess genetically rooted differences in the response of live specimens of corn (Zea Mays L.) to the toxic action of aluminium. Specimens from a susceptible and a tolerant inbred line were examined. The differences in their OCPA in vivo leaf spectra were evident and an interpretation is given based on the genetically controlled response of the inbreds to aluminium toxicity. An earlier discrimination among specimens is obtained with this technique than has been possible so far with previous techniques.

Non-destructive assessment of chlorophyll-deficient mutants of maize (Zea mays L.) by photoacoustic spectroscopy

Abstract Photoacoustic spectroscopy is an efficient tool for the non-destructive assessment of chlorophyll and carotenoid deficient mutants of Zea mays L. Intact leaf samples taken from the mutants Albina, Luteus I and Luteus II were compared with those from the corresponding isogenic normals. The results are compared with those obtained applying some commonly used destructive techniques.

Tissue, Cell, and Protoplast Culture of Maize (Zea mays L.)

In the past ten years considerable progress has been made on plant regeneration from tissues, cells, and protoplasts of various Gramineae species. In maize, plant regeneration was first described in 19751. After the initial reports on somatic embryogenesis in maize in 19822,3, plant regeneration from embryo-derived callus was extended to numerous other genotypes4,5,6. Genetic variability for plant regeneration has been reported within maize germplasms adapted to temperate7,8,9,10,11 and tropical6 regions. Further studies on the genetic control of somatic embryogenesis are still needed to better understand and manipulate this trait. Considerable attention has also been directed at studying the genetic variability observed among plants derived from maize callus for use in genetics and breeding12,13,14,15. The possibility of regenerating plants from maize cell suspension and protoplast cultures has opened new perspectives for direct gene transfer. Nevertheless, reports on the establishment of maize cell suspension and protoplast cultures capable of regenerating plants remain limited to a few genotypes16,17,18,19.

In Vitro Regeneration Capacity of Corn and Teosinte Genotypes

Germplasm sources from the Maydea Tribe are being utilized for maize improvement. Several species of this Tribe have been introduced into a research program and are being exploited through conventional breeding, tissue culture, and techniques of molecular biology, with the aim of gaining access to new corn genotypes. Teosinte species, as well as isogenic lines and commercial hybrids of Zea mays, are being used for tissue culture screening for regeneration capacity. Among teosinte materials, Zea diploperennis seems very attractive due to its perennial habit, whereas the annual Zea mexicana is the closest relative to domesticated corn. Interspecific hybrids from corn and teosinte species are also being utilized in this program.