Tropical Plant Biology

Mangrauthia, Satendra; Agarwal, Surekha; Sailaja, B.; Sarla, N.; Voleti, S.

2016 Tropical Plant Biology

doi: 10.1007/s12042-016-9170-7

Seed germination directly affects growth and yield of rice. Germination process is highly dependent on temperature which regulates expression of several genes and proteins in germinating tissue. Whole genome mRNA sequencing of rice germinated at optimum (30 °C) and high temperature (42 °C) was performed using Ion Torrent Sequencing. Bioinformatics analysis of sequence data was done to survey the expressed genes, gene ontology, and pathway analysis. High temperature altered the expression of genes involved in fatty acid, amino acid, carbohydrate, and energy metabolism. Genes involved in reserve degradation, protein folding and stress responses were also significantly affected. Induced expression of genes like dehydration responsive element binding (DREB), RAB (responsive to ABA), and late embryogenesis abundant (LEA) proteins suggested important role of these proteins in high temperature germinated (HTG) rice. The pathway analysis of differentially expressed genes at high temperature suggested the altered expression of transcripts associated with ABA and jasmonate signalling, antioxidants (peroxidase and ascorbate peroxidase), heat shock proteins (HSP 20 and HSP70 family), heat shock protein binding protein1 (HSPBP1, HSP70-interacting protein) and other stress associated pathways. In present scenario where very limited information is available on genome wide transcripts expression during germination process, the transcriptome study done in rice provides an opportunity to better understand the genes expression and regulation of seed germination, which is highly influenced by temperature.

Soares, Douglas; Sattler, Mariana; Ferreira, Marcia; Praça-Fontes, Milene

2016 Tropical Plant Biology

doi: 10.1007/s12042-016-9171-6

Tissue culture has been widely employed in Jatropha curcas L. for the clonal multiplication of superior genotypes. However, the evaluation of genetic stability is necessary to detect somaclonal variants. In this context, the present aim was to evaluate the genetic stability of J. curcas plantlets, obtained via indirect organogenesis, by means of ISSR markers. To supply the explant sources for in vitro propagation, the first generation of plants was produced from in vitro germination of J. curcas seeds. Fragments of cotyledonary leaves were inoculated into medium supplemented with 1.5 mg L−1 BAP and 0.05 mg L−1 of IBA for induction of callogenesis. The resulting calli were transferred to bud induction medium. Subsequently, the buds were cultured in medium for elongation, giving rise to the second generation of plants. These plants provided new buds, which were excised and subcultured in elongation medium, yielding a third generation of plants. To evaluate genetic stability in three plant generations, twelve ISSR primers were used, resulting in 124 bands showing 41.93 % of polymorphism. Increase was observed in the level of somaclonal variation (SV) over the generations. The present study reports, for the first time, the analysis of genetic stability in J. curcas plantlets regenerated via indirect organogenesis by means of ISSR markers. The results suggest that the indirect route is associated to higher levels of genetic instability, which also increased with successive subcultures. The ISSR markers were efficient in detecting SV, and the generated genetic variability may be useful for breeding programs.

Leelambika, M.; Mahesh, S.; Jaheer, M.; Tripathi, P.; Kumar, P.; Sathyanarayana, N.

2016 Tropical Plant Biology

doi: 10.1007/s12042-016-9174-3

Integrating targeted metabolic profiling with genetic diversity estimates is vital for selecting genetic stocks for breeding as well as mapping a biochemical trait. In Mucuna pruriens (L.) DC., copious amount of L-Dopa in seeds is viewed both as a boon and bane. Our objective of this work was to assess in conjunction both L-Dopa and genomic diversity in a selected set of germplasm to elucidate their relationship and identify parents for L-Dopa breeding/mapping. The findings revealed good genetic as well as metabolic (L-Dopa) diversity among the studied accessions. However, we could not establish direct relationship between these two as the marker data measured using AFLP and ISSR were not correlated with the seed L-Dopa contents. Based on the consensus information from both the data sets, seven parental combinations have been suggested. These findings are expected to pave way for genetic improvement as well as genetic mapping of L-Dopa trait besides integration of molecular markers in M. pruriens breeding programs.

Medeiros, Amanda; Furtado, Cristiane; Leite, Francinaldo; Souto, Valeska; Setta, Nathalia; Sluys, Marie-Anne; Kitajima, João; Costa, Ana; Benedito, Vagner; Scortecci, Katia

2016 Tropical Plant Biology

doi: 10.1007/s12042-016-9175-2

Sugarcane is a tropical crop used for sugar and biofuel production in tropical and equatorial regions of the globe. Sugarcane flowering is intrinsically induced in equatorial regions due to long-day conditions. Flower development is problematic for this crop because it halts vegetative growth, leading to a reduction of the sugar accumulated in the stalks, and significant yield loss. Notwithstanding, the identification of genes differentially expressed in contrasting cultivars can potentially reveal markers and tools to generate genotypes more suitable for expanding the geographical limits of this crop. Thus, dissecting the flowering gene expression network under field conditions is highly relevant for breeding. We report the analysis of subtractive cDNA libraries produced from shoot apical meristem of cultivars contrasting for flowering time growing in production fields under equatorial conditions. Transcripts with homology to POLYPHENOL OXIDASE (PPO), CALMODULIN (CAM), PHOSPHATIDYLCHOLINE/PHOSPHATIDYLINOSITOL-TRANSFER PROTEIN (SEC14), OBTUSIFOLIOL-14-Α-DEMETHYLASE (CYP51), 14–3-3, and the phosphotransferases SHAGGY KINASE (GSK), PROTEIN KINASE C INHIBITOR (PKCI), and SERINE/THREONINE PHOSPHATASE (PP1) were identified as differentially expressed in the subtractive libraries and further chosen for RT-qPCR validation and in silico interactome analyses. Our results suggest that ScPPO, ScSEC14 and Sc14–3-3 may act as flowering inhibitors. RT-qPCR data also revealed two 14–3-3 isoforms as potential flowering markers. Sc14–3-3 was structurally and phylogenetically characterized and its genomic architecture was analysed in two BAC clones, showing that they probably correspond to two different loci with confirmed synteny to other grass genomes. This work reveals potential novel mechanisms of flowering in grasses with implications to crop breeding.

Devi, Soibam; Kumaria, Suman; Rao, Satyawada; Tandon, Pramod

2016 Tropical Plant Biology

doi: 10.1007/s12042-016-9177-0

Carnivorous plants are among the curiosities of nature being different from the normal plants in their mode of nutrition. These plants have fascinated several researchers for centuries. They are also characterized by synthesis of bioactive compounds which are used as a mechanism for self defense. These compounds possess a broad spectrum of biological activities such as antiparasitic, antibacterial, insecticidal, fungicidal, anti-inflammatory, antipyretic, antiproliferative activities. Although, several antimicrobial drugs have been introduced during the recent decades, the problems of microbial infections resistant to synthetic pesticides still exist which necessitate the introduction of novel antimicrobial agents with additional modes of actions than the currently available therapeutic agents. Naphthoquinones are one of the most studied bioactive compounds which have been reported to inhibit the growth of proliferative cells and microbes. Efforts have been made to induce the biosynthesis of naphthoquinone in different species of carnivorous plants. It has been demonstrated that the accumulation of naphthoquinones in carnivorous plants was increased by injecting chitin into the plant tissues. Also, their biosynthesis could be enhanced by the incorporation of elicitors in in vitro cultures of plants. In the present review, we discuss the applications of naphthoquinones and its biosynthesis in carnivorous plants.

Mudge, A. M.; Hamdani, A.; Pilotti, C.; Godwin, I.

2016 Tropical Plant Biology

doi: 10.1007/s12042-016-9179-y

Our aim was to assess parental and population genetic variability in a partially nested set of breeding populations from the breeding program at Dami Research Station (West New Britain, PNG). Twenty microsatellite markers were tested for their ability to characterize genetic variation in oil palm populations bred at Dami Research Station. One hundred and twenty six individuals, including 100 F1 tenera hybrids of Dami Deli crossed with either AVROS, Ghana or AVROS/Ghana breeding lines were analysed. Eighteen of these markers were polymorphic within and among populations, amplifying 103 alleles in oil palm. Three individuals of other palm species (Cocos nucifera and two Phoenix spp.) were included as outliers. With these markers we have the power to distinguish individual palms, hence we conclude that they will facilitate association of markers with important phenotypic traits to streamline future breeding and selection.