Rapid results of peach palm seed viability: a methodological proposition for the tetrazolium test

ABSTRACT: Prior to commercialization, seeds of peach palm (Bactris gasipaes Kunth) have to undergo the germination test, whose well-established methodology takes 120 days. Due to their recalcitrant behavior, the seeds have short longevity when stored (around 30-45 days), which makes it challenging to select the most viable ones for marketing. This study aimed to determine a methodology for the tetrazolium test to be carried out in peach palm seeds, in order to fast deliver results that can be correlated to the germination test. Different forms of pre-conditioning, preparation, and staining were investigated via moisture content, germination, and tetrazolium tests, so as to define the vital parts of the seed and sort out the viability classes. For the seed lot under study, the tetrazolium test delivered results supported by the germination test when the following procedures were adopted: pre-conditioning by water submersion (20 °C for 24 h), longitudinal cut adjacent to the embryo, and half-seed immersion (embryo + endosperm) in a 1.0% tetrazolium solution for 4 h at 30 °C. Having fulfilled these criteria, it became possible to separate the peach palm seeds into two classes (viable or non-viable).

Mutations in the DNA demethylase OsROS1 result in a thickened aleurone and improved nutritional value in rice grains

The rice endosperm, consisting of an outer single-cell layer aleurone and an inner starchy endosperm, is an important staple food for humans. While starchy endosperm stores mainly starch, the aleurone is rich in an array of proteins, vitamins, and minerals. To improve the nutritional value of rice, we screened for mutants with thickened aleurones using a half-seed assay and identified thick aleurone 2–1 (ta2-1), in which the aleurone has 4.8 ± 2.2 cell layers on average. Except for starch, the contents of all measured nutritional factors, including lipids, proteins, vitamins, minerals, and dietary fibers, were increased in ta2-1 grains. Map-based cloning showed that TA2 encodes the DNA demethylase OsROS1. A point mutation in the 14th intron of OsROS1 led to alternative splicing that generated an extra transcript, mOsROS1, with a 21-nt insertion from the intron. Genetic analyses showed that the ta2-1 phenotype is inherited with an unusual gametophytic maternal effect, which is caused not by imprinted gene expression but rather by the presence of the mOsROS1 transcript. Five additional ta2 alleles with the increased aleurone cell layer and different inheritance patterns were identified by TILLING. Genome-wide bisulfite sequencing revealed general increases in CG and CHG methylations in ta2-1 endosperms, along with hypermethylation and reduced expression in two putative aleurone differentiation-related transcription factors. This study thus suggests that OsROS1-mediated DNA demethylation restricts the number of aleurone cell layers in rice and provides a way to improve the nutrition of rice.

PENGEMBANGAN METODE PENETAPAN KADAR AIR BENIH SAGA POHON (Adenanthera pavoninaL) DENGAN METODE OVEN SUHU RENDAH DAN TINGGI

Pengujian kadar air benih secara umum telah diatur oleh International Seed Testing Association untukberbagai keperluan, namun beberapa komoditi belum diatur secara jelas termasuk benih saga pohon. Oleh karenaitu pengembangan uji kadar air pada benih saga pohon dirasa perlu untuk dilakukan. Penelitian ini bertujuan untukmengembangkan uji kadar air benih saga pohon dengan dua metode oven yaitu suhu rendah dan tinggi. Penelitiandilaksanan di Lab. Agroekoteknologi, Universitas Trilogi sejak September-Desember 2016. Penelitian terdiri atasdua percobaan yaitu dengan metode oven suhu rendah (103±2)oC dan suhu tinggi (133±2)oC yang keduanyamenggunakan Rancangan Acak Kelompok dua faktor yaitu perlakuan benih saat di oven dan lamanya pengovenan.Untuk metode oven suhu rendah, faktor perlakuan benih saat di oven terdiri atas tiga taraf yaitu benih utuh, benihdibelah dua, benih dihaluskan dan lamanya pengovenan terdiri atas empat taraf yaitu 17 jam, 19 jam, 21 jam, dan23 jam. Untuk metode oven suhu tinggi, faktor perlakuan benih saat dioven terdiri atas tiga taraf yaitu benih utuh,benih dibelah dua, benih dihaluskan dan faktor lamanya pengovenan terdiri atas lima taraf yaitu 1 jam, 2 jam, 3jam, 4 jam, dan 5 jam. Hasil percobaan menunjukkan bahwa kadar air benih saga pohon dapat dilakukan denganmetode oven suhu rendah selama 17 jam dengan perlakuan benih dibelah dua atau selama 19-23 jam denganperlakuan benih utuh. Pengujian kadar air dengan metode suhu tinggi untuk perlakuan lamanya pengovenan dapatdilakukan selama 1 jam dan untuk perlakuan benih saat di oven dapat dilakukan dalam keadaan benih utuh.Kata kunci: benih utuh, benih dibelah dua, benih dihaluskan, lamanya pengovenan.ABSTRACTInternational Seed Testing Association generally rules the testing method of seed moisture content forvarious purposes. However, some commodities have not been clearly regulated including saga seeds. Therefore,the development of seed moisture content testing for saga seeds is considered necessary. The objective of the studywas to develop seed moisture content testing using two oven methods, namely low and high constant temperature.It was conducted at Integrated Lab. of Agroecotechnology, Department of Agroecotecnology, Trilogi Universitystarting from September to December 2016. Two experiments which were low constant temperature oven method(103±2) oC and high constant temperature oven method (133±2) oC were tested using two factors randomizedgroup design. The factors were seed treatment in the oven and period of seed drying. Low constant temperaturemethod used 3 levels of seed treatment (whole seed, half seed, and ground seed, respectively) and 4 levels of dryingperiod (17, 19, 21, and 23 hours, respectively). While high constant temperature method used 3 levels of seedtreatment (whole seed, half seed, and ground seed, respectively) and 5 levels of drying period (1, 2, 3, 4, and 5hours, respectively). The results showed that saga moisture content could be determined using low temperaturemethod with 17-hour drying period for half seeds or 19-23 hours of drying period for whole seeds. As for hightemperature method, seed moisture content testing could be done when seeds were dried for 1 hour, while for seedtreatment in the oven conducted for whole seeds.Key words: whole seed, half seed, ground seed, period of seed drying.

Grevillea (Proteaceae) seed coats contain inhibitors for seed germination

The purpose of this research was to examine the effect of the seed coat on seed dormancy in Grevillea (Proteaceae) species, and to further investigate the existence of germination inhibitors in Grevillea seed coat extracts. Seed dormancy of 18 Grevillea accessions involving 17 species was investigated: results indicated that removal of seed coat increased seed germination from 0–6% (intact seeds) to 83–100% for the Grevillea accessions and removal of half seed coat resulted in no increase in seed germination. Grevillea seed coat extracts reduced germination of barley, canola, lupin and ryegrass seeds by 48, 57, 10 and 38% respectively. The extracts also reduced seedling growth of the above four species. Ryegrass seeds showed no germination on the 3rd day after imbibition in the presence of Grevillea seed coat extracts compared with 88% germination for the control. Thus, our results showed that seed coat is a major factor determining Grevillea seed dormancy and removal of seed coat dramatically increased seed germination. Grevillea seed coat extracts reduced seed germination and seedling growth of other species. We conclude that there is exogenous seed dormancy in Grevillea species and the chemical(s) in the seed coat is a major factor inhibiting seed germination.

Comparative analysis of genetically modified maize by implementation of a half-seed extraction technique

The development of transgenic plants resulted in the need to utilize the various molecular methods (e.g., ELISA, real - time PCR etc.) for the detection or analysis of the presence or absence of a specific trait in a particular plant (Bt in this study). The overall aim of this study was to optimize a half – seed extraction technique as part of a laboratory protocol for transgenic maize plants and to explore the possibility of using the following molecular techniques: horizontal isoelectric focusing, real - time PCR and ELISA, as methods for detection of the Bt trait for incorporation into the half – seed extraction protocol.

Endo-β-mannanase activity is associated with the completion of embryogenesis in imbibed carrot (Daucus carota L.) seeds

Development of the rudimentary embryo in mature carrot (Daucus carota) seed during imbibition was characterized. The small embryo in the carrot seed, located in the micropylar region, elongated into the lateral part during imbibition and attained about two-thirds the length of the seed before radicle protrusion. Developing embryos excised from imbibed seeds were only capable of germinating in both water and Murashige–Skoog (MS) medium when they reached maximum size. The corrosion cavity into which the embryo grew enlarged concomitantly with endosperm degradation. The expression of endo-β-mannanase (EC 3.2.1.78), which is assumed to be involved in endosperm degradation, was characterized. A cDNA encoding an endo-β-mannanase was obtained by reverse transcription polymerase chain reaction (RT-PCR) using total RNA extracted from 24-h-imbibed carrot seeds. The full-length cDNA (DcMAN1) exhibited 64% deduced amino acid sequence identity with tomato (Lycopersicon esculentum) seed germination-associated mannanase (LeMAN2). DcMAN1 mRNA and endo-β-mannanase activity were first detected in the micropylar-half seed and then in the lateral-half seed. The timing of the appearance of DcMAN1 mRNA and endo-β-mannanase activity in the lateral-half seed corresponded with that of embryo development into this region. These results suggest that the expression of DcMAN1 and endo-β-mannanase activity in imbibed carrot seeds is associated with the enlargement of the corrosion cavity, which accompanies embryogenesis.

Correlation between high molecular weight gluten subunits composition and bread-making quality in Brazilian wheat

Bread-making quality is one of the most important targets in the genetic improvement of wheat. Although extensive analyses of quality traits such as farinography, sodium dodecyl sulfate (SDS) sedimentation, alveography, and baking are made in breeding programs, these analyses require high amounts of seeds which are obtained only in late generations. In this experiment the statistical correlations between the high molecular weight subunit of glutenin and bread-making quality measured by alveograph, farinograph and SDS sedimentation were evaluated. Seventeen wheat genotypes were grown under the same conditions, each producing about 1 kg of seeds for the evaluations. The high molecular weight (HMW) glutenin subunits were analyzed by SDS-PAGE. Statistical correlations were highly significant between HMW glutenin subunits and alveograph and SDS sedimentation. These results indicate the possibility of manipulating major genes for wheat seed quality by coupling traditional breeding with non-destructive single seed analysis. Only half seed is necessary to perform the SDS-PAGE analysis. Therefore, the other half seed can be planted to generate the progeny. Seed yield and SDS sedimentation were statistically correlated, indicating the possibility of simultaneous selection for both traits