Inheritance of photo-sensitivity in pigeonpea

Pigeonpea [Cajanus cajan (L.) Millsp.] is a short-day legume species and the late maturing genotypes are more photosensitive than early types. To generate information about the inheritance of photo-sensitivity, this study was conducted under natural and artificially extended (16 h) photo-periods using F1, F2 and BC1F1 generations. Under natural photo-period, F1 hybrids showed partial dominance of earliness; while in F2, a normal distribution that was skewed towards earliness was observed. In contrast under extended photo-period, the spread of F2 data was wide with discontinuities recorded at day 70, 82 and 103. Chisquare tests, when applied to F2 and BC1F1 data, suggested that three dominant genes (PS3, PS2 and PS1) controlled the expression of photo-sensitivity. These genes were found operating in a hierarchical order with PS2 and PS1 genes failing to express in the presence of PS3 gene. Similarly in the absence of PS3 gene, PS2 expressed but it masked the expression of PS1. Further, PS1 gene expressed only when both PS3 and PS2 were in recessive homozygous state. Hence, the proposed genetic model for photosensitivity in pigeonpea is PS3 > PS2 > PS1 and photoinsensitive genotype being a triple recessive (ps3ps3ps2 ps2ps1ps1)

Determination of the cyanobacterial toxin cylindrospermopsin in algal food supplements

For the analysis of blue–green algal food supplements for cylindrospermopsin (CYN), a C18 solid-phase extraction column and a polygraphitized carbon solid-phase extraction column in series was an effective procedure for the clean-up of extracts. Determination of CYN was by liquid chromatography with ultraviolet light detection. At extract spiking levels of CYN equivalent to 25–500 μg g−1, blue–green algal supplement recoveries were in the range 70–90%. CYN was not detected in ten samples of food supplements and one chocolate product, all containing blue–green algae. The limit of detection for the method was 16 μg g−1, and the limit of quantification was 52 μg g−1

A mechanism for inhibiting cross-fertilization in pigeonpea (Cajanus cajan (L.) Millsp.)

Natural out-crossing imposes considerable costs and inefficiencies in breeding, evaluation and commercialization of pigeonpea (Cajanus cajan (L.) Millsp.). This note reports identification of a modification of floral morphology which inhibits cross-fertilization. Floral morphology and possible mechanisms of action of this character are discussed

A New Source of Genetic Male Sterility in Pigeonpea

The identification of a new source of genetic male sterility in pigeonpea is reported. This source differs from that reported by Reddy et al, (1977), and oytological examination indicates that the abnormal anther development involves degeneration of the pollen mother cells at the young tetrad stage. This form of male sterility has been recovered in phenological classes ranging from 52 to 80 days to flower for December sowings at 27 S. The character is being maintained in ten phenological groups. This new source of genetic male sterility mil widen the genetic base for hybrid production in pigeonpea

Varietal Improvement of Pigeonpea for Smallholder Livestock Production Systems

Pegeonpea (Cajanus cajan) is widely grown in the tropics and subtropics as a soures of seed for human nutrition. I t i s most commonly used as jhai (dry s p l i t seed) i n vegetarian-based diets 3n the Indlan subcontinent. The seed contalns 20-25% protein. However, as we show i n t h i s 2aper pigeonpea seed also has considerable potential for animal feed and the p l a n t a s forage

Photoperiodic response and accelerated generation turnover in chickpea

Rapid generation advancement enables the breeder to produce and test near homozygous lines in a shorter period of time. Chickpea (Cicer arietinum) is a quantitative long-day plant. Three experiments were conducted, two at ICRISAT Center Hyderabad and one at Bangalore, India, from December 1978 to August 1979 to assess potential of extended daylength to shorten the life cycle by early flower induction. The studies involved cultivars of different maturity groups. Twenty-four hour daylength treatment by using incandescent lights induced early flowering. All cultivars flowered simultaneously and took 32 to 35 days after sowing, in contrast to 32 to 74 days taken for 50% flowering under normal daylengths. Plants exposed to 24-h daylength had slightly increased plant height, more pods and larger seeds in one of the experiments. Physiologically mature pods could be harvested as early as 62 days after sowing from plants induced to flower early by 24-h treatment. Once flowering was induced, continuation of the extended daylength treatment had no effect on maturity. This technique will allow harvesting of more than one generation per year

Gene action in short-duration pigeonpeas

F1-F2 hybrids from a half diallel set of crosses involving 7 early Cajanus cajan lines were studied for yield and a number of yield-related traits. Parental performance was a good predictor of breeding value for most traits in the F1, but in the F2 a significant positive association between GCA effects and the parental performance was seen only for number of days to flowering. GCA variance predominated for all traits in the F1 and F2. The results suggested exploitation of the additive genetic variation in breeding for improvement of the cro

Genetic rearrangements in <i>Pseudomonas amygdali</i> pathovar <i>aesculi </i>shape coronatine plasmids

Plant pathogenic Pseudomonas species use multiple classes of toxins and virulence factors during host infection. The genes encoding these pathogenicity factors are often located on plasmids and other mobile genetic elements, suggesting that they are acquired through horizontal gene transfer to confer an evolutionary advantage for successful adaptation to host infection. However, the genetic rearrangements that have led to mobilization of the pathogenicity genes are not fully understood. In this study, we have sequenced and analyzed the complete genome sequences of four Pseudomonas amygdali pv. aesculi (Pae), which infect European horse chestnut trees (Aesculus hippocastanum) and belong to phylogroup 3 of the P. syringae species complex. The four investigated genomes contain six groups of plasmids that all encode pathogenicity factors. Effector genes were found to be mostly associated with insertion sequence elements, suggesting that virulence genes are generally mobilized and potentially undergo horizontal gene transfer after transfer to a conjugative plasmid. We show that the biosynthetic gene cluster encoding the phytotoxin coronatine was recently transferred from a chromosomal location to a mobilizable plasmid that subsequently formed a co-integrate with a conjugative plasmid

A new gene for male sterility in pigeonpea (Cajanus cajan (L). Millsp.)

Several forms of female fertile and male sterile mutants in pigeonpea (Cajanus cajan (L). Millsp.) have been reported. A translucent anther type of male sterile characterised by non-separation of tetrads that is associated with a persistent tapetum is conditioned by a single recessive gene, ms1 (Reddy et al., 1977; Reddy et al., 1978). By contrast, a male sterile plant identified in breeding line B15B by Wallis et al. (1981) has shrivelled, arrowhead-shaped, non-dehiscent, brown-coloured anthers, and the pollen mother cells degenerate at the early tetrad stage (Dundas et al., 1981). This paper reports studies to determine the inheritance of the B15B male sterile character and its allelic relationship to the translucent anther type