Granular and powdered lime improves soil properties and maize (Zea mays l.) performance in humic Nitisols of central highlands in Kenya.

Acidic soils pose a major challenge for crop production in heavily weathered tropical soils, especially due to the high toxicity of aluminum (Al), low cation exchange capacity, and low availability of phosphorus (P) to plants. Lime application was recommended to alleviate soil acidity problems. Granular CaCO3 lime was introduced into the Kenyan market as an alternative to powdered CaCO3 and CaO-lime for small Kenyan farms, providing uniform distribution and efficient application. The aim of this study was therefore to investigate the effectiveness of different types of powdered and granular lime individually and in combination with mineral fertilizers in improving soil properties and maize yield. The study was conducted at two sites, Kirege (extremely acidic) and Kangutu (moderately acidic). Experiments were conducted in a randomized complete block design repeated four times in two consecutive seasons: long rain (LR) in 2016 and short rain (SR) in 2016. Three types of lime were applied before planting. Selected chemical properties of the soil were analyzed before and after the experiment. Maize and stover yield data were collected and analyzed. Results showed that lime application significantly increased soil pH and decreased exchangeable acidity. Powdered calcium carbonate (CaCO3) showed the highest pH increase in both extreme (+19%) and moderate (+14%) acid sites. All types of lime and fertilizer applications alone significantly increased the available soil P at both the seasonal and site levels. However, maize grain yield was lower with fertilizer alone or lime alone than with lime and fertilizer combination. Powdered CaCO3+ fertilizer was found to give the highest grain yields on both very acidic (5.34 t ha-1) and moderately (3.71 t ha-1) acid sites. In the study, combining powdered CaCO3 lime with fertilizers was most effective in improving acidic soils by decreasing soil acidity and increasing available phosphorus, which ultimately increased grain yield. The results of this study recommend the use of powdered CaCO3 as an effective and practical solution for farmers facing soil acidification problems.

Genome-wide analysis of the homeodomain-leucine zipper (HD-ZIP) gene family in peach (Prunus persica).

In this study, 33 homeodomain-leucine zipper (HD-ZIP) genes were identified in peach using the HD-ZIP amino acid sequences of Arabidopsis thaliana as a probe. Based on the phylogenetic analysis and the individual gene or protein characteristics, the HD-ZIP gene family in peach can be classified into 4 subfamilies, HD-ZIP I, II, III, and IV, containing 14, 7, 4, and 8 members, respectively. The most closely related peach HD-ZIP members within the same subfamilies shared very similar gene structure in terms of either intron/exon numbers or lengths. Almost all members of the same subfamily shared common motif compositions, thereby implying that the HD-ZIP proteins within the same subfamily may have functional similarity. The 33 peach HD-ZIP genes were distributed across scaffolds 1 to 7. Although the primary structure varied among HD-ZIP family proteins, their tertiary structures were similar. The results from this study will be useful in selecting candidate genes from specific subfamilies for functional analysis.

Genetic diversity and relationships among different tomato varieties revealed by EST-SSR markers.

The genetic diversity and relationship of 42 tomato varieties sourced from different geographic regions was examined with EST-SSR markers. The genetic diversity was between 0.18 and 0.77, with a mean of 0.49; the polymorphic information content ranged from 0.17 to 0.74, with a mean of 0.45. This indicates a fairly high degree of diversity among these tomato varieties. Based on the cluster analysis using unweighted pair-group method with arithmetic average (UPGMA), all the tomato varieties fell into 5 groups, with no obvious geographical distribution characteristics despite their diverse sources. The principal component analysis (PCA) supported the clustering result; however, relationships among varieties were more complex in the PCA scatterplot than in the UPGMA dendrogram. This information about the genetic relationships between these tomato lines helps distinguish these 42 varieties and will be useful for tomato variety breeding and selection. We confirm that the EST-SSR marker system is useful for studying genetic diversity among tomato varieties. The high degree of polymorphism and the large number of bands obtained per assay shows that SSR is the most informative marker system for tomato genotyping for purposes of rights/protection and for the tomato industry in general. It is recommended that these varieties be subjected to identification using an SSR-based manual cultivar identification diagram strategy or other easy-to-use and referable methods so as to provide a complete set of information concerning genetic relationships and a readily usable means of identifying these varieties.

A novel and efficient strategy for practical identification of tomato (Solanum lycopersicon) varieties using modified RAPD fingerprints.

Tomato breeding and variety development have led to the generation of a large number of varieties in many countries worldwide. This has created a growing and urgent need for an improved strategy for genotyping and identification since the traditional methods based on phenotype are growing unreliable. DNA markers could provide distinct benefits in tomato variety identification; however, DNA fingerprint analyses have not made DNA marker data readily usable for identification of varieties in tomato and other crops. A manual cultivar and/or variety identification diagram (MCID) strategy has been developed and has been found to make DNA markers more usable for the identification of genotyped plant individuals. We adopted this strategy, using modified RAPD markers to identify 42 tomato varieties from different geographical origins and seed merchants. All of the varieties were clearly separated and individually identified by reproducible fingerprints of only 6 RAPD primers. The tomato MCID that is generated is usable for the identification of any two or more tomato varieties. In addition, fewer primers can be used to make a distinction between varieties using this approach, since the selected fingerprints from each primer are used after they have been generated. The information in this first version of the tomato MCID can be enriched through identification and incorporation of more varieties and adaptation to other molecular markers in order to provide a more comprehensive tomato variety identification service for the horticultural industry.

Genome-wide analysis of the AP2/ERF superfamily in peach (Prunus persica).

We identified 131 AP2/ERF (APETALA2/ethylene-responsive factor) genes in material from peach using the gene sequences of AP2/ERF amino acids of Arabidopsis thaliana (Brassicaceae) as probes. Based on the number of AP2/ERF domains and individual gene characteristics, the AP2/ERF superfamily gene in peach can be classified broadly into three families, ERF (ethylene-responsive factor), RAV (related to ABI3/VP1), and AP2 (APETALA2), containing 104, 5, and 21 members, respectively, along with a solo gene (ppa005376m). The 104 genes in the ERF family were further divided into 11 groups based on the group classification made for Arabidopsis. The scaffold localizations of the AP2/ERF genes indicated that 129 AP2/ERF genes were all located on scaffolds 1 to 8, except for two genes, which were on scaffolds 17 and 10. Although the primary structure varied among AP2/ERF superfamily proteins, their tertiary structures were similar. Most ERF family genes have no introns, while members of the AP2 family have more introns than genes in the ERF and RAV families. All sequences of AP2 family genes were disrupted by introns into several segments of varying sizes. The expression of the AP2/ERF superfamily genes was highest in the mesocarp; it was far higher than in the other seven tissues that we examined, implying that AP2/ERF superfamily genes play an important role in fruit growth and development in the peach. These results will be useful for selecting candidate genes from specific subgroups for functional analysis.