Identification of a major gene and RAPD markers for yellow seed coat colour in Brassica napus.

The development of yellow-seeded Brassica napus for improving the canola-meal quality characteristics of lower fibre content and higher protein content has been restricted because no yellow-seeded forms of B. napus exist, and their conventional development requires interspecific introgression of yellow seed coat colour genes from related species. A doubled-haploid (DH) population derived from the F1 generation of the cross 'Apollo' (black-seeded) x YN90-1016 (yellow-seeded) B. napus was analysed via bulked segregant analysis to identify molecular markers associated with the yellow-seed trait in B. napus for future implementation in marker-assisted breeding. A single major gene (pigment 1) flanked by eight RAPD markers was identified co-segregating with the yellow seed coat colour trait in the population. This gene explained over 72% of the phenotypic variation in seed coat colour. Further analysis of the yellow-seeded portion of this DH population revealed two additional genes favouring 'Apollo' alleles, explaining 11 and 8.5%, respectively, of the yellow seed coat colour variation. The data suggested that there is a dominant, epistatic interaction between the pigment I locus and the two additional genes. The potential of the markers to be implemented in plant breeding for the yellow-seed trait in B. napus is discussed.

A theory of broadband matching for optical heterodyne receivers.

A theory of broadband matching for an optical heterodyne receiver consisting of a semiconductor photodiode followed by an IF broadband amplifier is presented in this paper. It is assumed that a finite linear lumped lossless interstage network is used for the broadband matching of the optical receiver, and the restrictions thereby imposed by the diode on the gain of the optical receiver are obtained both in integral and nonintegral forms. Several types of rational function approximations to an ideal flat gain characteristic of the optical receiver are then considered, and synthesis procedures for thelossless interstage networks to realize these approximations are presented. Explicit expressions are given for the amount of tolerance of broadband performance obtained with these networks.

On the problem of broadband signal and noise performance of direct detection optical receivers.

A theory of broadband signal and noise performance of a direct detection optical receiver is presented in this paper. Explicit expressions are given for the gain and noise factor of the optical receiver, consisting of a photodiode followed by a high gain, low noise baseband amplifier. It is assumed that a linear lumped lossless interstage network is placed between the diode and the amplifier to obtain broadband performance from the optical receiver. The constraints imposed by the photodiode on the wideband characteristics of the gain G(R) and noise factor F(R) of the optical receiver are obtained in integral and nonintegral forms.