Floral organogenesis requires coordinated interactions between genes specifying floral organ identity and those regulating growth and size of developing floral organs. With the aim to isolate ...regulatory genes linking both developmental processes (i.e., floral organ identity and growth) in the tomato model species, a novel mutant altered in the formation of floral organs was further characterized. Under normal growth conditions, floral organ primordia of mutant plants were correctly initiated, however, they were unable to complete their development impeding the formation of mature and fertile flowers. Thus, the growth of floral buds was blocked at an early stage of development; therefore, we named this mutant as
(
). Genetic analysis performed in a segregating population of 543 plants showed that the abnormal phenotype was controlled by a single recessive mutation. Global gene expression analysis confirmed that several MADS-box genes regulating floral identity as well as other genes participating in cell division and different hormonal pathways were affected in their expression patterns in
mutant plants. Moreover,
mutant inflorescences showed higher hormone contents, particularly ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC) and strigol compared to wild type. Such results indicate that
may have a key function as positive regulator of the development of floral primordia once they have been initiated in the four floral whorls. This function should be performed by affecting the expression of floral organ identity and growth genes, together with hormonal signaling pathways.
Avian eggs have a proteinaceous cuticle. The quantity of cuticle varies and the deposition of a good cuticle in the uterus (Shell-gland) prevents transmission of bacteria to the egg contents.
To ...understand cuticle deposition, uterus transcriptomes were compared between hens with i) naturally good and poor cuticle and, ii) where manipulation of the hypothalamo-pituitary-gonadal-oviduct axis produced eggs with or without cuticle. The highest expressed genes encoded eggshell matrix and cuticle proteins, e.g. MEPE (OC-116), BPIFB3 (OVX-36), RARRES1 (OVX-32), WAP (OVX-25), and genes for mitochondrial oxidative phosphorylation, active transport and energy metabolism. Expression of a number of these genes differed between hens laying eggs with or without cuticle. There was also a high expression of clock genes. PER2, CRY2, CRY1, CLOCK and BMAL1 were differentially expressed when cuticle deposition was prevented, and they also changed throughout the egg formation cycle. This suggests an endogenous clock in the uterus may be a component of cuticle deposition control. Cuticle proteins are glycosylated and glycosaminoglycan binding genes had a lower expression when cuticle proteins were deposited on the egg. The immediate early genes, JUN and FOS, were expressed less when the cuticle had not been deposited and changed over the egg formation cycle, suggesting they are important in oviposition and cuticle deposition. The uterus transcriptome of hens with good and poor cuticle deposition did not differ.
We have gained insights into the factors that can affect the production of the cuticle especially clock genes and immediate early genes. We have demonstrated that these genes change their expression over the period of eggshell formation supporting their importance. The lack of differences in expression between the uterus of hens laying eggs with the best and worse cuticle suggest the genetic basis of the trait may lie outside the oviduct.
Key message
Genetic interactions of
UFD
gene support its specific function during reproductive development of tomato; in this process,
UFD
could play a pivotal role between inflorescence architecture ...and flower initiation genes.
Tomato (
Solanum lycopersicum
L.) is a major vegetable crop that also constitutes a model species for the study of plant developmental processes. To gain insight into the control of flowering and floral development, a novel tomato mutant,
unfinished flower development
(
ufd
), whose inflorescence and flowers were unable to complete their normal development was characterized using double mutant and gene expression analyses. Genetic interactions of
ufd
with mutations affecting inflorescence fate (
uniflora, jointless and single flower truss
) were additive and resulted in double mutants displaying the inflorescence structure of the non-
ufd
parental mutant and the flower phenotype of the
ufd
mutant. In addition,
ufd
mutation promotes an earlier inflorescence meristem termination. Taken together, both results indicated that
UFD
is not involved in the maintenance of inflorescence meristem identity, although it could participate in the regulatory system that modulates the rate of meristem maturation. Regarding the floral meristem identity, the
falsiflora
mutation was epistatic to the
ufd
mutation even though
FALSIFLORA
was upregulated in
ufd
inflorescences. In terms of floral organ identity, the
ufd
mutation was epistatic to
macrocalyx,
and
MACROCALYX
expression was differently regulated depending on the inflorescence developmental stage. These results suggest that the
UFD
gene may play a pivotal role between the genes required for flowering initiation and inflorescence development (such as
UNIFLORA, FALSIFLORA, JOINTLESS and SINGLE FLOWER TRUSS
) and those required for further floral organ development such as the floral organ identity genes.
The cuticle is an invisible barrier that protects the internal egg contents from microorganisms entering through gas exchange pores. Eggs which have a good cuticle are least likely to be penetrated ...by microorganisms and improved cuticle cover should reduce vertical transmission of microorganisms and improve biosecurity. The aim was to carry out a genome wide association study for cuticle deposition in 3 independent populations of laying hens using tartrazine and lissamine green staining. Eggs from ∼8,000 hens represented 2 White Leghorn and 1 Rhode Island Red breed. Estimates of heritability using pedigree or genomic relationship matrices were in the 0.2 to 0.3 range.
The results were breed specific. Across the populations, genomic regions on chromosomes 1, 2, 4, 5, and 8 were identified as significantly associated with cuticle deposition. No single loci had a large effect. A comparison was made with genes differentially expressed in the shell gland when cuticle deposition was manipulated, however none were obvious candidates for cuticle deposition. The results support the polygenic nature of the trait and the information will help in the future to understand the genetic variance and what might control cuticle deposition and the microbiological safety of the egg.
Preaxial polydactyly is a congenital hand anomaly predominantly of sporadic occurrence, which is frequently associated with abnormalities of the Sonic hedgehog signalling pathway. In experimentally ...induced preaxial polydactyly, radial aplasia is also frequently observed. To determine if there is a correlation between preaxial polydactyly and radial aplasia, we induced ectopic Sonic hedgehog signalling during chicken limb development with application of a smoothened-agonist (SAG) or retinoic acid. Application of SAG caused malformations in 71% limbs including preaxial polydactyly (62%) and forearm abnormalities (43%). Retinoic acid application induced malformations in 56% of limb including preaxial polydactyly (45%) and forearm abnormalities (50%). Radial dysplasia and ulnar dimelia were observed in both experimental conditions. We demonstrate that ectopic Sonic hedgehog signalling may cause both preaxial polydactyly and predictable forearm anomalies and that these conditions could potentially be classified as one embryological group. We propose a unifying model based on known models of ectopic Sonic hedgehog signalling.
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