Fruit ripening : physiology, signalling and genomics/ Edit.: Pravendra Nath; Mondher Bouzayen

321 hal.: ill, tab.; 24 cm

Fruit ripening : physiology, signalling and genomics/ Edit.: Pravendra Nath; Mondher Bouzayen

321 hal.: ill, tab.; 24 cm

Cytoplasmic male sterility in sorghum: Organization and expression of mitochondrial genes in Indian CMS cytoplasms

Cytoplasmic male sterility in sorghum has been reported in a number of varieties originating in different geographical regions (India, Africa and America). We have attempted to characterize three male sterile cytoplasms of Indian origin designated as Maldandi, Guntur and Vizianagaram by studying restriction fragment length polymorphisms (RFLPs) and expression patterns of 14 mitochondrial genes. Our results indicate that the cytoplasms, classified tentatively as Indian A4 types, are distinct from the American A4 and A1 types. Although they are identical to each other with respect to the location of 10 of the mitochondrial genes selected, they can be distinguished from each other on the basis of RFLPs inatp6, atp9 and rrn18. Further the three cytoplasms differ from their maintainers in the location of nad3, rpsl2 and atpA. Differences are also observed in the pattern of expression ofatpA between all the sterile lines and their respective maintainers

Differences in kinetics of F<SUB>1</SUB>-ATPases of cytoplasmic male sterile, maintainer and fertility restored lines of sorghum

A comparative analysis of mitochondrial functions was carried out in the cytoplasmic male sterile A1 (milo) cytoplasm, its maintainer and the fertility restored lines. The study of temperature dependence (15-45&#176; C) of the rates of uncoupled whole chain electron transport in the three lines did not reveal any differences between them at any of the temperatures studied. The partitioning of electrons between the cyanide-sensitive and the cyanide-insensitive respiratory pathways also did not show any differences between the three lines. However, differences in the kinetic properties of the isolated mitochondrial F1-ATPases between the sterile and the fertility restored lines were clearly observed. The studies revealed that while a strong negative cooperativity between the subunits of the F1-ATPases of the fertile maintainer and the fertility restored hybrid lines was observed, the F1-ATPase from the sterile line, in contrast, showed much reduced negative cooperativity. It is proposed that these differences in kinetic properties of the F1-ATPase may play a role in the expression of the CMS trait at the time of anther formation

Organization and post-transcriptional processing of the psb B operon from chloroplasts of Populus deltoides

Chloroplast genes are typically organized into polycistronic transcription units that give rise to complex sets of mono- and oligo-cistronic overlapping RNAs through a series of processing steps. The psbB operon contains genes for the PSII (psbB, psbT, psbH) and cytochrome b6f (petB and petD) complexes which are needed in different amounts during chloroplast biogenesis. The functional significance of gene organization in this polycistronic unit, containing information for two different complexes, is not known and is of interest. To determine the organization and expression of these complexes, studies have been carried out on crop plants by different groups, but not much information is known about trees. We present the nucleotide sequences of PSII genes and RNA profiles of the genes located in the psbB operon from Populus deltoides, a tree species. Although the gene organization of this operon in P. deltoides is similar to that in other species, a few variations have been observed in the processing scheme