Morphological characterization of forage sorghum genotypes for its various DUS traits

The present investigation was conducted to characterize 20 genotypes of sorghum {Sorghum bicolor (L.) moench} on the basis of 33 morphological characters provided by Protection of Plant Variety & Farmer’s Right Act (PPV&FRA) for Distinctiveness Uniformity and Stability (DUS) testing in sorghum. Experimental results revealed that maximum variation was found on the basis of glume colour among the genotypes i.e. G 46, HC 308, HJ 513 had green white, IS 3237, SSG 9, HC 171 had yellow white, SSG 59-3, COFS 29 had grayed purple, S 437-1, SGL-87, S 540-S, SSG (PSSG) had grayed yellow and remaining seven genotypes had grayed orange glume colour. The studied traits showed five genotypes had distinct state of expression. Genotype S-540 showed very high plant height upto the base of flag leaf, HC 136 had compact panicle density at maturity, COFS 29 had very long glume length, SSG 59-3 had distinct expression for days to panicle emergence (50 % of the plants with 50 % of anthesis) and COFS 29 and IS 18551 had short and very long leaf width of blade, respectively. The Principal Component Analysis (PCA) revealed principal Factor (PFI) and Principal Factor (PFII) with maximum variability (64.99 %). Classification of genotypes on the basis of DUS traits provided identification of key characteristics of various genotypes.

GENETIC COMPONENTS OF GRAIN CHARACTERS IN RICE (Oryza sativa L.)

Hayman’s analysis of variance (ANOVA) indicated importance of both additive and non-additive genetic components for all the grain characters. The ANOVA showed unidirectional dominance for the characters viz. kernel breadth, upper empty glume length and endosperm-embryo ratio, asymmetrical gene distribution for the characters viz. grain length, grain breadth, kernel length, kernel breadth and kernel thickness and residual dominance effects for all the grain characters studied. Five out of nine grain characters viz. grain breadth, grain thickness, kernel breadth, kernel thickness and upper empty glume length followed the simple additive-dominance genetic model. The rest of the grain characters showed nonallelic gene interaction or epistasis. According to Vr-Wr graph, partial dominance was involved in the action of genes governing the inheritance of grain breadth, grain thickness, kernel breadth and kernel thickness while complete dominance was involved in the inheritance of upper empty glume length. BR4828-54-4-1-4-9 contained the most of the recessive genes for four characters except upper empty glume length while Amol3 appeared to possess most of the recessive genes. On the other hand, Minikit for grain breadth, Amol3 for grain thickness and BRRI dhan29 for kernel breadth, kernel thickness and upper empty glume length possessed most of the dominant genes for the respective characters. The components of variance demonstrated involvement of both additive and dominant components in the inheritance of grain breadth, grain thickness, kernel breadth, kernel thickness and endosperm-embryo ratio. The distribution of dominant and recessive genes was unequal in the parents for grain breadth, kernel breadth, grain thickness, kernel thickness and upper empty glume length. Again, net dominance effects were in the negative direction for all the grain characters. There was drastic influence of environment on all the five grain characters following simple additive-dominance genetic model. Heritability in narrow sense (h2 n) was very high for grain breadth, grain thickness, kernel breadth and kernel thickness. However, h2 n for upper empty glume length was moderate. DOI: http://dx.doi.org/10.3329/bjpbg.v21i1.17047

Genetic architecture of quantitative trait loci associated with morphological and agronomic trait differences in a wild by cultivated barley cross

Hordeum vulgare subsp. spontaneum is the progenitor of cultivated barley (Hordeum vulgare L.). Domestication combined with plant breeding has led to the morphological and agronomic characteristics of modern barley cultivars. The objective of this study was to map the genetic factors that morphologically and agronomically differentiate wild barley from modern barley cultivars. To address this objective, we identified quantitative trait loci (QTLs) associated with plant height, flag leaf width, spike length, spike width, glume length in relation to seed length, awn length, fragility of ear rachis, endosperm width and groove depth, heading date, flag leaf length, number of tillers per plant, and kernel color in a Harrington/OUH602 advanced backcross (BC2F8) population. This population was genotyped with 113 simple sequence repeat markers. Thirty QTLs were identified, of which 16 were newly identified in this study. One to 4 QTLs were identified for each of the traits except glume length, for which no QTL was detected. The portion of phenotypic variation accounted for by individual QTLs ranged from about 9% to 54%. For traits with more than one QTL, the phenotypic variation explained ranged from 25% to 71%. Taken together, our results reveal the genetic architecture of morphological and agronomic traits that differentiate wild from cultivated barley.

Cytology, fertility, and morphology of Elymus kengii (Keng) Tzvelev and E. grandiglumis (Keng) A. Löve (Triticeae: Poaceae)

This study reports on the cytogenetics, fertility, mode of reproduction, and morphological variation of two perennial Triticeae grasses, Elymus kengii (Keng) Tzvelev and Elymus grandiglumis (Keng) A. Löve, from west central China. Both species are allohexaploids (2n = 42), self-fertile, and morphologically distinct on the basis of their plant color, glume length, and lemma and rachis vestiture. F1 hybrids between these two species are partially fertile and morphologically intermediate to their parents. Analysis of chromosome pairing in hybrids between E. grandiglumis or E. kengii and the following "analyzer" species, Psathyrostachys juncea (Fisch.) Nevski (NN), Psathyrostachys huashanica Keng (NN), Elymus lanceolatus (Scribn. &Smith) Gould (SSHH), Elymus dentatus (Hook. f.) Tzvelev ssp. ugamicus (Drob.) Tzvelev (SSYY), Elymus ciliaris (Trin.) Nevski (SSYY), Pseudoroegneria spicata (Pursh) A Löve (SS), and Pseudoroegneria tauri (Boiss. &Bal.) A. Löve (SSPP), suggested that both taxa contain the S, Y, and P genomes. This represents a new genome combination not previously reported and shows that the P genome from the crested wheatgrasses (Agropyron) has been involved in polyploid evolution within the. Triticeae.Key words: genome, meiosis, chromosome pairing, interspecific hybrids, Elymus, Triticeae.

Genome analysis of Thinopyrum bessarabicum and T. elongatum

Thinopyrum bessarabicum (2n = 14; JJ) was successfully crossed with T. elongatum (2n = 14; EE) but the reciprocal cross failed. Five of the 19 F1 plants headed in a greenhouse without being vernalized. Spikes of F1 hybrids were intermediate to those of the parents for number of florets per spike, glume length, and the first rachis internode length, but similar to those of T. bessarabicum and T. elongatum for spike length and number of spikelets per spike, respectively. Karyotypes of mitotic chromosomes in the parental species revealed that three of the seven chromosomes in the J and E genomes were similar in length and arm ratio. Meiosis in the F1 hybrids substantiated the conclusion from karyotype analysis that the other four chromosomes had undergone some structural rearrangements such as reciprocal translocation. Metaphase-I cells in hybrid plants averaged 2.68 I, 4.68 II, 0.27 III, 0.27 IV, and 0.01 V. Although 10% of the pollen grains were stainable with I2–KI, F1 plants of T. bessarabicum × T. elongatum did not set seed upon selfing. It is concluded that the J and E genomes are so closely related that the E genome designation should be changed to Je. The evidence reported here supports the transfer of Lophopyrum elongatum to the genus Thinopyrum. Wheat breeders should be able to utilize the genes in T. bessarabicum as readily as those in T. elongatum.Key words: Genome, mitosis, meiosis, karyotype, idiogram, hybrid.

Notes on the taxonomy and nomenclature of Festuca occidentalis and F. idahoensis

Festuca occidentalis occurs in open forests and glades, always in at least partial shade. In British Columbia it occurs from the U.S.A. border to about latitude 57° N. It has leaf structure, panicle structure, spikelet length, glume length, lemma length, lemma scabrosity, awn length, anther length, and ovary vestiture which are different from F. idahoensis. Festuca idahoensis is found in grasslands (including subalpine meadows) and in openings in dry forests bordering grasslands, always in open, nonshaded situations. In British Columbia it occurs from the U.S.A. border northward to about 51° N. Despite the recent lumping of these two taxa, morphological and ecological evidence strongly suggests that they should be treated as separate species.

A HISTOLOGICAL STUDY OF SEED SHATTERING IN REED CANARY GRASS

Individual spikelets of reed canary grass (Phalaris arundinacea L.) were examined histologically to determine the mechanism of seed shattering. It was observed that shattering is a two-stage process, involving disarticulation of the rachilla approximately 12 days after anthesis, followed by subsequent release of the seed from the glumes. In both high- and low-shattering greenhouse-grown material no spikelets were observed histologically in which the seed was still attached later than 14 days after anthesis. In low-shattering clones the glumes retained the seed within the spikelet. No clear-cut histological differences in glume structure were observed between high- and low-shattering clones. The presence of a constriction at the base of the glumes of some spikelets of high-shattering clones requires further investigation since this indicates the possibility of selection based on glume morphology. Differences in glume length and seed weight among clones were not significantly correlated with shattering percentage. However, within clones, shattered seeds were heavier than non-shattered seeds.