Mapping the Genetic Regions Responsible for Key Phenology-Related Traits in the European Hazelnut

An increasing interest in the cultivation of (European) hazelnut (Corylus avellana) is driving a demand to breed cultivars adapted to non-conventional environments, particularly in the context of incipient climate change. Given that plant phenology is so strongly determined by genotype, a rational approach to support these breeding efforts will be to identify quantitative trait loci (QTLs) and the genes underlying the basis for adaptation. The present study was designed to map QTLs for phenology-related traits, such as the timing of both male and female flowering, dichogamy, and the period required for nuts to reach maturity. The analysis took advantage of an existing linkage map developed from a population of F1 progeny bred from the cross “Tonda Gentile delle Langhe” × “Merveille de Bollwiller,” consisting in 11 LG. A total of 42 QTL-harboring regions were identified. Overall, 71 QTLs were detected, 49 on the TGdL map and 22 on the MB map; among these, 21 were classified as major; 13 were detected in at least two of the seasons (stable-major QTL). In detail, 20 QTLs were identified as contributing to the time of male flowering, 15 to time of female flowering, 25 to dichogamy, and 11 to time of nut maturity. LG02 was found to harbor 16 QTLs, while 15 QTLs mapped to LG10 and 14 to LG03. Many of the QTLs were clustered with one another. The major cluster was located on TGdL_02 and consisted of mainly major QTLs governing all the analyzed traits. A search of the key genomic regions revealed 22 candidate genes underlying the set of traits being investigated. Many of them have been described in the literature as involved in processes related to flowering, control of dormancy, budburst, the switch from vegetative to reproductive growth, or the morphogenesis of flowers and seeds.

Auxin-induced AUXIN RESPONSE FACTOR4 activates APETALA1 and FRUITFULL to promote flowering in woodland strawberry

Flowering time is known to be regulated by numerous pathways, such as the autonomous, gibberellin, aging, photoperiod-mediated, and vernalization pathways. These regulatory mechanisms involve both environmental triggers and endogenous hormonal cues. Additional flowering control mechanisms mediated by other phytohormones, such as auxin, are less well understood. We found that in cultivated strawberry (Fragaria × ananassa), the expression of auxin response factor4 (FaARF4) was higher in the flowering stage than in the vegetative stage. Overexpression of FaARF4 in Arabidopsis thaliana and woodland strawberry (Fragaria vesca) resulted in transgenic plants flowering earlier than control plants. In addition, FveARF4-silenced strawberry plants showed delayed flowering compared to control plants, indicating that FaARF4 and FveARF4 function similarly in regulating flowering. Further studies showed that ARF4 can bind to the promoters of the floral meristem identity genes APETALA1 (AP1) and FRUITFULL (FUL), inducing their expression and, consequently, flowering in woodland strawberry. Our studies reveal an auxin-mediated flowering pathway in strawberry involving the induction of ARF4 expression.

Sequence analysis and protein interactions of Arabidopsis CIA2 and CIL proteins

Background: A previous screening of Arabidopsis thaliana for mutants exhibiting dysfunctional chloroplast protein transport identified the chloroplast import apparatus ( cia ) gene. The cia2 mutant has a pale green phenotype and reduced rate of protein import into chloroplasts, but leaf shape and size are similar to wild-type plants of the same developmental stage. Microarray analysis showed that nuclear CIA2 protein enhances expression of the Toc75 , Toc33 , CPN10 and cpRPs genes, thereby up-regulating protein import and synthesis efficiency in chloroplasts. CIA2-like (CIL) shares 65% sequence identity to CIA2, suggesting that CIL and CIA2 are homologous proteins in Arabidopsis. Here, we further assess the protein interactions and sequence features of CIA2 and CIL. Results: Subcellular localizations of truncated CIA2 protein fragments in our onion transient assay demonstrate that CIA2 contains two nuclear localization signals (NLS) located at amino acids (aa) 62-65 and 291-308, whereas CIL has only one NLS at aa 47-50. We screened a yeast two-hybrid (Y2H) Arabidopsis cDNA library to search for putative CIA2-interacting proteins and identified 12 nuclear proteins, including itself, CIL, and flowering-control proteins (such as CO, NF-YB1, NF-YC1, NF-YC9 and ABI3). Additional Y2H experiments demonstrate that CIA2 and CIL mainly interact with flowering-control proteins via their N-termini, but preferentially form homo- or hetero-dimers through their C-termini. Moreover, sequence alignment showed that the N-terminal sequences of CIA2, CIL and NF-YA are highly conserved. Therefore, NF-YA in the NF-Y complex could be substituted by CIA2 or CIL. Conclusions: We show that Arabidopsis CIA2 and CIL can interact with CO and NF-Y complex, so not only may they contribute to regulate chloroplast function but also to modulate flower development.

Sequence analysis and protein interactions of Arabidopsis CIA2 and CIL proteins

Background: A previous screening of Arabidopsis thaliana for mutants exhibiting dysfunctional chloroplast protein transport identified the chloroplast import apparatus ( cia ) gene. The cia2 mutant has a pale green phenotype and reduced rate of protein import into chloroplasts, but leaf shape and size are similar to wild-type plants of the same developmental stage. Microarray analysis showed that nuclear CIA2 protein enhances expression of the Toc75 , Toc33 , CPN10 and cpRPs genes, thereby up-regulating protein import and synthesis efficiency in chloroplasts. CIA2-like (CIL) shares 65% sequence identity to CIA2, suggesting that CIL and CIA2 are homologous proteins in Arabidopsis. Here, we further assess the protein interactions and sequence features of CIA2 and CIL. Results: Subcellular localizations of truncated CIA2 protein fragments in our onion transient assay demonstrate that CIA2 contains two nuclear localization signals (NLS) located at amino acids (aa) 62-65 and 291-308, whereas CIL has only one NLS at aa 47-50. We screened a yeast two-hybrid (Y2H) Arabidopsis cDNA library to search for putative CIA2-interacting proteins and identified 12 nuclear proteins, including itself, CIL, and flowering-control proteins (such as CO, NF-YB1, NF-YC1, NF-YC9 and ABI3). Additional Y2H experiments demonstrate that CIA2 and CIL mainly interact with flowering-control proteins via their N-termini, but preferentially form homo- or hetero-dimers through their C-termini. Moreover, sequence alignment showed that the N-terminal sequences of CIA2, CIL and NF-YA are highly conserved. Therefore, NF-YA in the NF-Y complex could be substituted by CIA2 or CIL. Conclusions: We show that Arabidopsis CIA2 and CIL can interact with CO and NF-Y complex, so not only may they contribute to regulating chloroplast function but also to modulating flower development.

QUIZALOFOP-P-ETHYL CONTROLLING SOURGRASS (Digitaria insularis) AND GOOSEGRASS (Eleusine indica) IN INFESTED COFFEE AREAS

<p>Chemical control is the main weed management system in coffee crop. Herbicides alternatives controlling grass weeds in infested coffee areas are limited, mainly due to the few options of registered herbicides. Thus, it is important to evaluate selective post-emergence herbicide to control these important weeds in coffee crop. The objective of this work was to evaluate the selectivity, efficiency and agronomic viability of the herbicide IHH 0513 (Quizalofope-P-ethyl 50g ai L^-1) compared to Glyphosate on grass control in coffee crop. Two experiments were carried out in randomized blocks with four replications in the municipality of Lavras and Santana da Vargem (MG - Brazil) in a commercial coffee crop cultivar “Mundo Novo” and “Catuai” to evaluate the herbicide effectiveness in the crop rows. The experimental design was a randomized block design with seven treatments and four replications. Treatments consisted of IHH 0513 doses (Quizalofope-P-ethyl 25, 50, 75 and 100 g ai ha^-1) compared to the standard GLI OVER (Glyphosate 480 g ia L^-1) at the dose of 1680g ai ha^-1 + Iharol at 0.5% v/v. Application occurred when sourgrass and goosegrass were at the beginning of development with up to 4 tillers (early vegetative stage) and in a second trial, at advanced stages of development (highly branched and /or flowering). Control assessments in percentage were performed at 7, 14, 21 and 28 days after application (DAA) of the treatments. A note of phytotoxicity was given by the EWRC scale (1964). The control of weeds was evaluated in each experimental plot using the visual notes scale of FRANS et al. (1986), where: 0% represents no control, and 100% total control of the species in question, compared to the population present in the non-weed control. In general, the dose of 1500 and 2000 mL per hectare of IHH 0513 (75 and 100 g ai ha^-1) for the weeds at early vegetative stage presented the highest levels of controls (above 90%). The dose of 2000 mL per hectare (100 g ai ha^-1) was efficient at 28 DAA to control more developed plants. No symptoms of phytotoxicity caused by the IHH 0513 product were detected at any dose tested. Quizalofop-P-ehtyl can be recommended for integrated weed management in coffee for sourgrass and goosegrass.</p>