G. M. Reddy

Plantlet regeneration from glume calli of maize (Zea mays L.)

SummaryTotipotent callus cultures were established from anther-free glumes of ‘Sweet corn’, ‘Seed corn,’ ‘DHM 103’ and ‘DHM 101’ on MS medium supplemented with 1–2 mg/l 2,4-D. The callusing response of the glumes was tested on six different media. Glumes at the uninucleate stage of pollen development callused with a high frequency compared to other stages. Organogenesis was observed in 40% of the cultures on media devoid of hormones. A total of 76 plantlets were regenerated on medium with 0.5–1.0 mg/l of both IAA and kinetin. Cytological observations in root tips indicated a diploid chromosome number (2n=20).

Biochemical changes in embryogenic and non-embryogenic calli of Zea mays L.

Abstract Embryogenic cultures derived from immature glumes of Zea mays L. were studied for the isoenzyme patterns of peroxidase, esterase and malate dehydrogenase. Two slow migrating cathodal isoperoxidase, specific esterase and malate dehydrogenases present in the embryogenic calli, were absent in non-embryogenic calli, which may indicate an association of these specific isozymes with embryogenic calli.

Genetic and biochemical basis of scent in rice ( Oryza sativa L.)

SummaryThe inheritance and biochemical basis of scent in rice was studied in the F2 population along with the F1 and its two parents, scented and non-scented ‘Pokura’ rice strains. The F1 plants were found to be nonscented while the F2 plants seggregated into a 3∶1 ratio (non-scented: scented). In scented F2 seggregants and in the scented parental strain, a fast moving esterase isozyme, Rf 0.9, is missing whereas it is present in all nonscented F2 seggregants, F1s, and in the non-scented parent. This suggests that the absence of a specific esterase isozyme is associated with the scent character in rice.

Amino acid profiles in some scented rice varieties.

SummaryTwelve scented (basmati) and one non-scented variety were analysed for their amino acid composition. The essential amino acid profiles of scented varieties when compared with non-scented, revealed that these varieties exhibited higher values, which ranged from 2.82 to 4.86 gm/100 gm protein for lysine, 1.92 to 3.13 for methionine, 1.67 to 4.23 for tyrosine, 3.65 to 4.91 for phenylalanine, 5.50 to 8.95 for leucine, 2.25 to 3.40 for isoleucine, 2.84 to 3.46 for threonine, 3.36 to 5.33 for valine. When these values were compared to FAO recommended standards, it was observed that most of the scented varieties had comparable or superior values, while varieties such as, ‘Type 3’, ‘Basmati sufaid 100’, ‘Likitimachi’, ‘Randhunipagalu’ and ‘Basmati 370’ showed superior lysine, phenylalanine, leucine, and methionine content. These observations suggest that the scented varieties posses better amino acid profiles and exhibit superior nutritional qualities, which could be utilised in breeding varieties with improved amino acid composition.

Some induced dwarfing genes non-allelic to Dee-geo-woo-gen gene in rice, variety Tellakattera

SummaryThe allelic nature of five dwarfs (d6, d7, d8, d9 and d10), recovered in M2 after ethyl methanesulphonate treatment of a local rice variety Tellakattera, was studied in relation to the Dee-geo-woo-gen (DGWG) dwarfing gene. The behaviour of the different crosses of the dwarfs with DGWG in F1 and the segregation pattern in F2 clearly demonstrate that these induced dwarfs are non-allelic to the DGWG dwarfing gene. In view of the extensive use of this gene in developing most of the high yielding rice varieties, the new dwarfing genes of Tellakattera may be exploited as alternative sources, to avoid genetic vulnerability.

Genetic analysis of certain in vitro and in vivo parameters in pigeonpea (Cajanus cajan L.).

SummaryStudies on callus growth and shoots/cotyledon, using seven different genotypes of pigeonpea and their hybrid progenies, revealed continuous variation for these traits. Hence, the type of gene action influencing in vitro cell proliferation and differentiation has been investigated in a diallel analysis of seven pigeonpea genotypes. Highly significant average heterosis was recorded for callus growth and seed yield/plant. In general, the F1 hybrids which showed heterosis for callus growth also exceeded their better parent for yield/ plant. Combining ability analysis revealed both additive and non-additive gene effects for callus growth, while number of shoots/cotyledon was mostly governed by non-additive gene effects. The genotype, ‘ICP 7035’, was the best general combiner for callus growth and shoot forming capacity of cotyledons. Two cross combinations, ‘7186’ב6974’ and ‘7035’בT-21’, showed maximum SCA effects for callus growth and shoots/cotyledon. Callus dry weight was positively correlated with seed yield/plant and seedling weight. The strong positive association of callus growth with seed yield indicates the possibility of using this system for mass screening and selection of superior hybrids.

Studies on protein content and yield levels in rice

SummaryCrosses between low and high protein varieties revealed the dominance of low protein over high protein content. The number of desirable segregants with the double combination of high protein and yield were scored in each generation. The increasing frequency of desirable segregants from the F2 to the F3 generation in all the crosses increase the chances of selecting desirable recombinants for propagating improved rice varieties. Hybridisation followed by selection may help in developing varieties with high protein content and superior yield potential.

Aminoacid profiles in the study of phylogenetic relationships in the genusOryza

SummaryThe amino acid profiles in seeds of thirteen different species ofOryza, including two cultivated rices,O. glaberrima andO. sativa and the two major geographical racesindica andjaponica were studied using an automatic amino acid analyser to assess differences in the profiles of cultivated species and their wild progenitors. The polygon graphic method was employed to envision the species relationship. Essential amino acid profiles in different species were also compared with those of the Food and Agriculture Organization (FAO) standards. The results suggest a wide range of variability amongOryza species for lysine (up to 4.4% as against 3.5% in cultivated rices) and other essential amino acids. This will be of considerable interest to rice breeders, when after overcoming genetic barriers, the possible utilization of these species in rice breeding becomes feasible.

Free aminoacid pattern and species relationship in genus Oryza.

SummaryUsing the two-dimensional paper-chromatographic technique, free-aminoacid analysis was made on nine diploids and five allotetraploid species of Oryza, to study the biochemical and physiological bases of species relationships. The relationship between different species was inferred on the basis of similarity or differences in polygon patterns of aminoacids, drawn using Ellisons paired affinity values. Among the diploid species, O. sativa, O. perennis subsp. balunga, O. glaberrima and O. breviligulata showed similar polygon patterns, suggesting close relationships. The other diploid species differed in their polygon pattern, reflecting species differences. In the tetraploid species, O. alta and O. latifolia, and O. minuta, O. schweinfurthiana and O. malampuzhaensis, showed similar polygon patterns. Polygon maps of O. punctata failed to show any similarity with O. officinalis, but some similarity was observed between O. punctata and O. schweinfurthiana.

Differential expression of esterase and MDH isozymes during in vitro culture in maize [Zea mays L.]

Isozyme patterns of esterase and malate dehydrogenase were analyzed at different stages of in vitro culture of immature embryos and glumes of Zea mays L. viz. explant, callus formation, root formation and shoot formation. Significant changes in isoenzyme patterns of esterase and MDH were observed besides the appearance of specific and new isozymes. Specific fast migrating isozymes were noted in differentiating calli of embryo and glume calli which were absent at other stages suggesting a possible association of these isozyme patterns with in vitro differentiation.