Solanum tuberosum cultivars, Solanum tuberosum × Solanum tuberosum subsp. andigena hybrids and breeding clones with different time to maturity were screened for drought tolerance in field plots located in the coastal desert of Peru. Variation for drought tolerance was illustrated by clone-dependent differences in tuber yield and yield loss under drought conditions. Neither changes in stomatal conductance nor maximum quantum yield of chlorophyll fluorescence were quantitatively associated with yield or yield loss under drought. In contrast, relative vegetation index (reflectance at 800 nm / reflectance at 650 nm) and normalized difference vegetation index [(reflectance at 800 nm -reflectance at 650 nm) / (reflectance at 800 nm + reflectance at 650 nm)] on day 25 and day 40 after drought were correlated with yield. The vegetation indices are related to leaf area index and above ground biomass, which appeared to be major determinants for yield in the tested cultivars under drought. Nitrate reductase activity was significantly decreased in drought-exposed plants, but activity depletion was independent of yield or yield maintenance. Putative drought tolerance genes were differentially expressed in leaves of water stressed genotypes. Induction of the protein phosphatase 2C gene was positively associated with yield maintenance under drought. Furthermore, Potato Research (2007) 50:71-85

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The 12D3 antigen present in Babesia bovis has been evaluated as a recombinant vaccine candidate and the 12d3 coding sequence has been reported for an Australian and an USA (Texas) isolate of B. bovis. However, no approach has been conducted to perform analysis of 12d3 sequence conservation on a larger number of B. bovis isolates. This could provide important information to determine whether a recombinant vaccine containing this antigen could be widely used. This study reports the cloning and sequencing analysis of the 12d3 coding region in 20 different B. bovis isolates collected from various geographical regions in the tropics and subtropics of Mexico. Comparative analysis of the consensus nucleotide sequences obtained for each isolate revealed a high degree of conservation (94-99% sequence identity) among the 12d3 alleles present in the Mexican isolates when compared with the 12d3 ORF sequences from the Texan (T2Bo) B. bovis isolate. Similarly, BLASTX sequence homology search showed a high percent identity (93-99%) of the deduced amino acid 12D3 sequence as compared with the T2Bo isolate sequence. The high level of sequence conservation in 12d3 among the 20 B. bovis isolates collected from geographically distant locations in Mexico suggests that there exists a minimal bovine-host immunological pressure which could be translated into antigenic diversity or variation, and most probably this is reflected in the non-inmunodominant characteristic of the 12D3 antigen as it has been previously described in the literature. 12D3 antigen can be considered as a viable candidate for inclusion in a recombinant vaccine for cattle babesiosis caused by B. bovis in Mexico.

En el Estado de Sinaloa, México, son dinamicos los cambios en prácticas agrícolas, tipos de variedad y estrategias de mejoramiento genético del cultivo del maíz (Zea mays L.), lo que ha permitido que el rendimiento de grano se incrementara en 63 % durante el periodo 1991-1993. Al respecto, los agricultores han adelantado la fecha de siembra del ciclo otoño-invierno (O-I) en relación al periodo óptimo determinado en estudios previos. En el ciclo OI 2002-2003 se sembraron, en condiciones de riego, ocho híbridos comerciales en cinco fechas de siembra espaciadas cada 15 d, de noviembre 15 a enero 15. Se tomaron datos de rendimiento de grano, días a floración masculina y femenina, altura de planta y mazorca, porcentaje de acame de raíz y tallo, calificación de roya (Puccinia sorghi) y de mazorca, así como las temperaturas diarias máxima, mínima y media. Hubo diferencias (P ≤ 0.01) en rendimiento de grano entre fechas de siembra, híbridos y para la interacción fechas de siembra x híbridos. El rendimiento más alto (promedio de los ocho híbridos) se obtuvo en la siembra de noviembre 15, 32 d antes que la fecha recomendada para el ciclo 1990-1991 (Diciembre 17). Los híbridos de grano blanco ‘H-375’ y ‘H-438’ tuvieron el rendimiento de grano más alto (promedio de cinco fechas de siembra), y ‘P-31G98 Y’ el más bajo. Las diferencias en temperatura entre los ciclos agrícolas, especialmente la temperatura máxima diaria, fue el factor más importante para explicar la interacción fecha de siembra x híbrido.