Citrus post-bloom fruit drop (caused by Colletotrichum acutatum) frequently occurs in the southwestern region of São Paulo State, Brazil. A survey of Colletotrichum isolates associated with symptoms of post-bloom fruit drop in São Paulo State showed C. gloeosporioides in addition to C. acutatum. The objectives of this study were to confirm the identification of C. gloeosporioides isolated from symptomatic citrus flowers, to test the pathogenicity of C. gloeosporioides isolates, to compare the development of disease caused by C. gloeosporioides and C. acutatum, and to determine the frequency of C. gloeosporioides in a sample of isolates obtained from symptomatic flowers in different regions of São Paulo State. Through the use of species-specific primers by PCR, 17.3% of 139 isolates were C. gloeosporioides, and the remaining 82.7% were C. acutatum. The pathogenicity tests, carried out in 3-year old potted plants of sweet oranges indicated that both species caused typical symptoms of the disease including blossom blight and persistent calyces. Incubation periods (3.5 and 3.9 days, respectively, for C. acutatum and C. gloeosporioides) and fruit sets (6.7 and 8.5%, respectively for C. acutatum and C. gloeosporioides) were similar for both species. The incidences of blossom blight and persistent calyces were higher on plants inoculated with C. acutatum than in those inoculated with C. gloeosporioides. Conidial germination was similar for both species under different temperatures and wetness periods. Under optimal conditions, appressorium formation and melanisation were higher for C. gloeosporioides than for C. acutatum. These results indicated that Colletotrichum gloeosporioides is a new causal agent of post-bloom fruit drop.

The effects of drought on water relations, gas exchanges, solutes accumulation, and catalase (CAT), ascorbato peroxidase (APX), and guaiacol peroxidase (GPX) activities were studied in five Arachis genotypes, grown under control or withholding water conditions. Drought stress reduced plant growth of all genotypes; the genotypes A. duranensis 7988 and A. stenosperma SV2411 being characterized as the most drought-sensitive and A. ipaensis as the most drought-tolerant. Data of transpiration and stomatal conductance confirmed the findings that A. ipaensis was more tolerant to drought conditions. Water deficit increased organic solutes content and reduced leaf water potential in all genotypes. The data suggest that solutes accumulation in roots may, at least in part, explain the greater tolerance of A. ipaensis to drought stress. CAT activity showed a significant increase in stressed leaves of sensitive genotypes. APX and GPX activities either increased or were not affected by drought in leaves of all genotypes.

The regular water supply during life cycle is essential to determine the yield in the legumes. In semiarid environments, the irregular rainfall and high temperature influence the phenology of crops impairing the yield. Peanut is an oleaginous crop with broad adaptation to tropical and semiarid climates, but yield is often harmed when plants face water irregularities during reproductive phase. The recommendation of cultivars tolerant to environments with water-limitation is indispensable to farmers in order to ensure reasonable production when drought settles down. Here, we evaluating peanut bred lines in order to assess drought tolerance based on physiological and yield traits, in greenhouse and field assays. In greenhouse experiment, 2 genotypes (BR 1, drought tolerant and the sensible LViPE-06) and 2 descendant bred lines (earliness-LBM Branco and a mid-runner, LBR Branco) were submitted to 21 days of total water supression. Diffusive resistance, transpiration and leaf water potential were measured by porometer (LI 1600), from fully expanded leaves at mid canopy. Root length was also measured at final period of water stress. Further, in a 2-year field experiment carried out in semiarid environment (Barbalha, CE, Brazil), the genotypes were evaluated under rainfed and irrigation, aiming to estimating the yield trait and the efficiency of drought tolerance. Physiological and yield traits of all genotypes were altered under water stress and significant responses were observed. Both top lines showed physiological ability to tolerance to drought, but LBM Branco, an earliness and upright line, was classified as drought tolerant showing behavior near to BR 1. The losses in pod and seed yield were low, comparing to runner parent (LViPE-06). LBR Branco showed an intermediary performance between parents and was classified as moderately tolerant. Based on physiological and agronomic performances, LBM Branco can later be recommended for management in semiarid environment.

The section Heteranthae of Arachis is endemic to Brazil, occurring mainly in the semi-arid northeastern region. The section is considered derived within the genus and includes only annual herbs. Most previous cytological evaluations were restricted to chromosome numbers and morphology. The present approach comprised karyomorphological evaluation in 10 accessions from five species of this section, including standard staining and fluorochrome banding [chromomycin A3 (CMA)/4 0 ,6-diamidino-2-phenylindole (DAPI)]. All accessions presented diploid chromosome numbers (2n = 20) with a prevalence of metacentric to submetacentric chromosome morphology. Arachis dardani, Arachis pusilla, and Arachis interrupta presented karyotypic formula 18m ? 4sm and satellite type 2, while Arachis sylvestris and Arachis giacomettii presented 16m ? 4sm and satellite type 10. Despite the conserved morphological features, higher diversity was detected in terms of size and number of GC-rich (CMA ?) heterochromatic blocks among the species; however, all of them were located in the pericentromeric regions. The species A. pusilla presented the highest number of GC-rich blocks, present in all chromosomes of the complement. Based on the data obtained and considering literature data, we suggest that A. dardani and A. interrupta occupy a basal position in the group due to their moderate asymmetry and satellite type. At least in A. pusilla, the constitutive heterochromatin seems to have suffered recent modifications of its constitution, in contrast to other species that present pericentromeric CMA ? blocks in all chromosomes. A. giacomettii and A. sylvestris are closely related to each other and also similar to the previously studied Arachis seridoensis, revealing two clear-cut subgroups within the section from the karyological point of view.

The gene introduced into plants confers resistance to boll weevil and fall armyworm. Transmission of the transgene occurred normally to T1 progeny. All plants showed phenotypically normal growth, with fertile flowers and abundant seeds. © 2015 Society of Chemical Industry.